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IOBC-WPRS Bulletin Vol. 102, 2014

 

IOBC-WPRS Bulletin Vol. 102, 2014

Working Group "Integrated Control in Protected Crops, Temperate Climate".
Preceedings of the meeting at Gent (Belgium), 14 - 18 September, 2014.
Editors: Irene Vänninen in collaboration with Joachim Audenaert.
ISBN 978-92-9067-283-8 [XVI + 264 pp.]

 

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Development of the omnivorous predator Dicyphus errans when fed on different prey regimes and its total prey consumption during the nymphal stage
Konstantina Arvaniti, Dionyssios Perdikis and Argyro Fantinou

Abstract: The native omnivorous predator Dicyphus errans (Wolff) (Heteroptera: Miridae) is usually reported in outdoor crops and in greenhouses in the Mediterranean basin and North-Central Europe. The effect of food availability rate on its nymphal development was investigated on tomato leaflets in Petri dishes in the following cases: a) when the predator had access to Ephestia kuehniella Zeller eggs (‘prey’) available ad libitum but only for 24 hours: 1) on the first day of the first instar, 2) on the first day of the second instar, 3) on the first day of the first and the third instar, and 4) when fed for 24 h at each nymphal instar (i.e. 5 meals in total). For comparison, development was recorded in the absence of prey and when prey was available continuously. The experiments were conducted at 25 ± 1 °C, 65 ± 5% RH, with a photoperiod of 16:8 (L:D) h. In the absence of prey, D. errans nymphs failed to molt to adults. When presented with a meal during the first instar a single adult (male) emerged after 21 days. When the meal was offered at the second instar adult emergence reached 20%, requiring 28.7 days on average. When two meals were offered, 60% of the nymphs reached adulthood, in 19.3 days; all nymphs reached adulthood in 19 days when fed at each instar. The total number of E. kuehniella eggs consumed by D. errans nymphs during their development was also determined. A total of 20, 40, 60, 80 and 110 E. kuehniella eggs were offered every single day to nymphs during their 1st, 2nd, 3rd, 4th and 5th instar, respectively. During their development D. errans female nymphs consumed 260.25 and male nymphs 208.57 eggs. On average, females took 17.3 days to reach adulthood and males took 16.7 days; 100% of the nymphs reached adulthood. The data collected may be useful in the development of mass rearing programs for D. errans and in its application in IPM strategies.

1-5

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Predation efficiency of predatory mites from different climatic origin under variable climates in Belgian greenhouses
Joachim Audenaert, Dominiek Vangansbeke, Ruth Verhoeven, Patrick De Clercq, Luc Tirry, Bruno Gobin

Abstract: In order to better adapt the use of predatory mites with the modern greenhouse climate regulation strategies, functional response models were constructed to demonstrate the impact of realistic climate variations on the predation efficiency on Tetranychus urticae eggs by Neoseiulus fallacis, Phytoseiulus persimilis and N. californicus predatory mites (Acari: Phytoseiidae).
First, two T regimes were compared at 70% RH and 16 L:8 D photoperiod: DIF 0 (constant T) and DIF 15 (variable T with a day-night difference of 15 °C). At mean T of 25 °C, DIF 15 reduced the predation efficiency of P. persimilis and N. californicus compared to DIF 0. At the lower mean T of 15 °C, however, N. californicus had a higher predation efficiency at DIF 15. The predation efficiency of N. fallacis was similar at DIF 15 and DIF 0 irrespective of the mean temperature.
Secondly, two RH regimes were compared, at constant T of 25 °C and constant photoperiod (16 L:8 D): RHCTE (constant 70% RH) and RHALT (alternating 40% L:70% D RH). P. persimilis and N. fallacis predated better at RHCTE than RHALT, but for N. californicus the opposite was true. The used strain of N. californicus is more adapted to periods of low RH as P. persimilis or N. californicus.
Thirdly, a summer regime (mean T of 25 °C, RH alternating 40% L:70% D and photoperiod 16 L:8 D) and winter regime (mean T of 15 °C, RH 70%, photoperiod 8 L:16 D) were evaluated. Under summer regimes, DIF 15 influenced the predation efficiency of P. persimilis and N. californicus negatively as compared to DIF 0. Under winter regimes, DIF 15 influenced predation efficiency of N. californicus and P. persimilis positively as compared to DIF 0. DIF had no influence on N. fallacis under winter and summer regimes.
We conclude that N. fallacis originating from temperate climate is less influenced by variable greenhouse climates compared to P. persimilis and N. californicus that originate from warmer and drier regions. For optimal control efficiency, predatory mites should be chosen by taking into account the actual greenhouse climate and the climate in the predatory mite’s region of origin. Research is ongoing to validate this hypothesis for other commercially used predatory mites.

7-13

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Seasonal abundance of aphid hyperparasitoids in organic greenhouse crops in The Netherlands
Chantal M. J. Bloemhard, Meindert van der Wielen, Gerben J. Messelink

Abstract: In this study we present the results of a survey on hyperparasitoid incidence in parasitized aphids among 10 organic growers of sweet pepper on different locations in The Netherlands. Monitoring took place during an entire growing season, from January till November. Parasitized aphids (mummies) were collected from the crop and from banker plants. The parasitoids and hyperparasitoids that emerged from the collected mummies were morphologically identified in the laboratory and the percentage of hyperparasitism was determined per sampling date. The most abundant hyperparasitoid species was Dendrocerus aphidum Rondani. The number of greenhouses infected with this species soon increased from 5 in February to 10 in April and the hyperparasitoids remained present till the end of the cropping season in November. The presence of these hyperparasitoids early in the season indicates that they probably overwinter in the greenhouses. Rates of hyperparasitism caused by this species increased in most greenhouses to 100 % in April-May. The second most abundant species was Asaphes suspensus Walker. The first infected greenhouses appeared in May and the relative abundance of this species increased after summer. In most cases the rates of hyperparasitism caused by this species remained low. The species Phaenoglyphis villosa (Hartig) was only found occasionally. Possible strategies to minimize risks of hyperparasitism are further discussed.

15-19

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The information content of sticky traps on pest and beneficial densities in greenhouse vegetables
Elias Böckmann, Rainer Meyhöfer

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21-22

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Prevention is better than cure: Early-season intervention to control whitefly on poinsettia
Michael Brownbridge, Rose Buitenhuis, Taro Saito, Angela Brommit, Paul Côté and Graeme Murphy

Abstract: Historically, poinsettia cuttings shipped into Ontario from offshore production facilities have carried very low levels of immature Bemisia whiteflies. These have been successfully controlled by preventative releases of parasitoids (Encarsia formosa, Eretmocerus mundus). In 2012 though, cuttings arrived into Ontario carrying large numbers of Bemisia eggs and nymphs. Parasitoid releases proceeded as normal but failed to regulate whitefly populations; multiple pesticide treatments were required to provide effective control. Endemic whitefly resistance (owing to heavy pesticide use in production facilities) means that insecticides registered in Canada frequently have reduced efficacy. Furthermore, pesticide residues on imported material can have a detrimental effect on parasitoid survival and performance. To ensure greater sustainability in poinsettia production, new methods of control are required to mitigate incoming pests on cuttings and ensure that biological control systems can be maintained through the crop production cycle. Several reduced-risk products, biopesticides and combination treatments, applied to infested cuttings by dipping immediately prior to sticking, were therefore evaluated to determine their relative efficacy against whitefly, ensure compatibility with parasitoids and to assess possible phytotoxic effects. A combination of insecticidal soap and Beauveria bassiana (BotaniGard® WP; BioWorks Inc., Victor, NY) was the most effective treatment tested; phytotoxic effects were minimal (some variation across cultivars) and survival of Encarsia and Eretmocerus was not affected following release onto treated leaves. The project has allowed effective treatments to be identified that can be readily implemented on a commercial scale.

23-28

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Considerations and combinations to improve control of pupating western flower thrips in chrysanthemums
Michael Brownbridge, Taro Saito, Paul Côté

Abstract: Western flower thrips (WFT) are a major impediment in greenhouse floriculture. They are pests of global significance, resistant to many conventional insecticides and in Canada today, there is only one registered product that will successfully control this insect. Biological control is the only viable option available to Canadian growers. The thrips life cycle provides two distinct environments and life stages that can be targeted with different natural enemies. Nematodes, primarily Steinernema feltiae (e.g., Nemasys®), applied as a drench treatment, are widely used against soil-dwelling stages (pro-pupae and pupae). Metarhizium brunneum (formerly anisopliae; Met52® granular biopesticide) is registered for thrips control in Canada. The fungus is incorporated into potting media and will infect and kill thrips entering the soil to pupate. The purpose of the current trial was to define efficient use practices for these biocontrol agents and confirm their compatibility. We investigated effects of plant growth stage on nematode deposition onto the soil, nematode-Met52compatibility, and the relative efficacy of individual and combined, i.e. Nemasys + Met52, treatments against WFT. As chrysanthemums grew and the density of the plant canopy increased, fewer nematodes reached the soil after each spray which may affect efficacy. Overall, Met52 appears to be compatible with S. feltiae. Individual nematode and fungus treatments had a measurable suppressive effect on thrips, but the combined nematode/fungus treatment provided superior control. WFT populations were consistently lower on plants receiving the combined treatment; at the conclusion of the trial (8 weeks) < 10 WFT/pot were recovered. Opportunities therefore exist to enhance the reliability and cost-effectiveness of thrips biocontrol agents by taking an integrated approach to their deployment.

29-35

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Systems approach: integrating IPM in the production system
Rose Buitenhuis

Abstract: We have been doing a lot of research to optimize biocontrol and to convince growers that biocontrol is the way to go, but good pest control is still hit or miss because we still concentrate too much on the individual components instead of on the whole picture. Using the systems approach, I think we can build more robust IPM programs and identify areas of weakness that have to be addressed by research or innovation.

37-43

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Biological control using predatory mites in low and fluctuating temperatures
Samuel Critchley, Nathan Medd, Richard GreatRex, Lina Zaghloul

Abstract: Improvements in cropping technology and the development of novel crop varieties allow growers to cultivate horticultural crops throughout a larger proportion of the calendar year. Some crops are now approaching all year round cropping where this was never possible before. Crops grown throughout the winter in passive greenhouses represent a particular challenge for the implementation of biological control. In this study we focused on improving biological control programmes in the southern Spanish region of Almeria. Using greenhouse climate data we were able to construct a model temperature profile representative of an ‘average day’ for various periods of the winter. In these conditions we analysed possible barriers to the successful implementation of predatory mites as biological control agents for Western Flower Thrips (Frankliniella occidentalis) and Whitefly (Trialeurodes vaporariorum and Bemisia tabaci). We show that the formulation of products is a key aspect in improving the control of these pests. IPM programme design and implementation strategies are discussed in-light of these findings and the wider relevance of the study is identified.

45-48

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Efficacy of control products against Bemisia tabaci Q biotype
Andrew G. S. Cuthbertson

Abstract: Bemisia tabaci continues to be a major pest of economically important crops worldwide. Within the UK B. tabaci remains a notifiable pest subject to a policy of eradication if found on propagators premises, plants moving in trade, and containment/eradication if outbreaks occur at nurseries. A range of chemical products and entomopathogenic fungi (EPF) were screened for their efficacy using the leaf dip technique against three life stages of B. tabaci Q biotype; eggs, second instar larvae and adults. There was a significant difference in the mortality of eggs after leaf dipping with the different active ingredients. Exposure to Tri-Tek, SB-Plant Invigorator, Gazelle, Dynamec and Certis Spraying Oil was followed by egg mortalities of 100, 96.6, 88.8, 84.1 and 67.8%, respectively. Efficacy of the products against the second larval instar stage also produced promising results. The fungus B. bassiana produced the highest mortality of all the products against B. tabaci instars (73%). The control given by Agri 50-E, Tri-Tek and SB-Plant Invigorator (all physically acting products) was also over 70%. Beauveria bassiana and Tri-Tek gave excellent control of adult B. tabaci with total mortality being obtained.

49-54

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New insights in aphid control using parasitoids
Nicolas Dassonville, Thierry Thielemans and Virginie Gosset

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55

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Toward developing sustainable management strategies for the tomato potato psyllid in covered crops in New Zealand
Melanie M. Davidson, Mette-Cecilie Nielsen, Jessica Vereijssen, Robin Gardner-Gee

Abstract: The tomato potato psyllid (Bactericera cockerelli (Šulc) Hemiptera: Triozidae) was first recorded in covered crops in New Zealand in 2006. Previously, this pest had not been found outside of North and Central America. The tomato potato psyllid has since become widespread throughout most of New Zealand in both indoor and outdoor crops. It is a pest on economically important solanaceous crops including potatoes, capsicums, and tomatoes. The psyllid not only causes direct damage through feeding, but also vectors the plant pathogenic bacterium Candidatus Liberibacter solanacearum. A number of applied research programmes have been undertaken to manage the psyllid aimed at lowering the pest and disease pressure, and while some of the strategies developed could be considered crop-specific, there is potential to transfer knowledge/strategies between the different cropping systems. A summary of the research undertaken to date is reviewed in relation to management strategies in covered crops.

57-63

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Can biochar play a role in the integrated control of diseases in protected crops?
Jane Debode, Caroline De Tender, Pieter Cremelie, Tommy D’Hose, Bart Vandecasteele, and Martine Maes

No abstract

65-66

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Side effects of modern pesticides on mummies of the parasitic wasp Eretmocerus mundus (Mercet) (Hymenoptera: Aphelinidae) under laboratory conditions
Mª Mar Fernández, Pilar Medina, Pedro del Estal, Guy Smagghe & Elisa Viñuela

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67-68

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Recent developments in the diagnostic approaches for agriculturally important Frankliniella species detection
Żaneta Fiedler, Arnika Przybylska, Halina Kucharczyk,, Aleksandra Obrępalska-Stęplowska

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69

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DNA barcoding of commercial biological control agents: a quality management framework
Andrew J. Frewin, Cynthia Scott-Dupree, Graeme Murphy, and Robert Hanner

Abstract: Biological control is a key component of greenhouse integrated pest management (IPM) programs throughout the world. Numerous organizations now rear and distribute biological control agents (BCAs) for greenhouse pest management and research purposes. Commercial arthropod colonies require replenishment with wild caught individuals to maintain high levels of fitness and hence BCA performance. However, this practice risks contaminating colonies with closely related species. These contaminant species have the potential to be distributed to greenhouse producers with unknown ramifications for biological control programs. Unfortunately, morphological identification of many BCA species can be challenging due to factors such as lack of taxonomic expertise and the presence of cryptic species. Alternatively, a standardized molecular approach can be applied to aid in the identification of BCA specimens as part of a quality management framework for both BCA producers and researchers. For this purpose we have constructed a DNA barcode reference library for most of the commercially available BCAs in North America. We highlight instances of divergence within some ‘species’ and provide recommendations for researchers using commercially obtained BCAs.

71-76

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Bemisia tabaci (Hemiptera: Aleyrodidae) in commercial poinsettia: impact of biocontrol on demographic trends
Andrew J. Frewin, Cynthia Scott-Dupree, Graeme Murphy, and Robert Hanner

Abstract: Bemisia tabaci (Gennadius) is an economically important pest of food and ornamental plants world-wide and is now recognized as a cryptic-species complex. In many regions, it is a particularly important pest of greenhouse poinsettia and two cryptic species from the B. tabaci complex, Mediterranean (Biotype Q) and Middle East Minor 1 (MEAM1: Biotype B), often infest poinsettia crops simultaneously. In general, the Mediterranean species has greater resistance to insecticides than MEAM1. This difference in pesticide susceptibility has the potential to influence growers’ management decisions, including the use of biological control vs. insecticides, and the choice of insecticide active ingredient. However, little is known about the impact of these decisions on the demographic trends of mixed species infestations in commercial-scale greenhouses. To address this question, we conducted a season long survey of B. tabaci populations in commercial poinsettia crops in Ontario, Canada. Using a molecular diagnostic technique to identify Mediterranean and MEAM1 population within the B. tabaci complex, we provide evidence that under biological control-based management, MEAM1 can displace Mediterranean, whereas under insecticide-based management Mediterranean populations will persist. The demographic shift observed in commercial greenhouses conforms to predictions based on the observation of mixed laboratory colonies of these two species. The use of biological control for B. tabaci management (in particular mixed species infestations) has the potential to preserve the efficacy of late-season insecticide applications if needed, whereas serial applications of insecticides throughout the duration of the crop will shift mixed-populations towards Mediterranean, increasing the risk of control failures.

77-82

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Interactions among natural enemies of the citrus mealybug: foraging behavior under the threat of intraguild predation
Gkounti T. Vasiliki, Dimitrios Ch. Kontodimas, Matilda Savopoulou-Soultani and Panagiotis G. Milonas

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83

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Alternative prey on the soil increases density of Amblyseius swirskii and Neoseiulus cucumeris on the plant and improves thrips control
Amir H. Grosman, Ana M. Guimarães Bernardo, Chantal Bloemhard, Gerben Messelink & Arne Janssen

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84

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Potential of strawberry aphids control by parasitoids
Thierry Hance, Christophe Salin

Abstract: In Belgium, three main species of aphids, Rhodobium porosum, Chaetosiphon fragaefolii and Aulacorthum solani can be present simultaneously and provoke huge losses in strawberry crops. The aim of the present work was to compare the activity and parasitism rates of seven species of Hymenoptera parasitoids to analyse their biocontrol potential on each aphid species. Using video recording of their behaviour, we first determined the acceptance of host aphid by parasitoids based on the numbers of antennae contacts followed by ovipositor contact, aphid survival, numbers of mummies produced and rate of parasitoids emergence under standardized conditions. We also determined the parasitism rate after a 24 h contact with 100 aphids. Finally, cage experiments under glasshouses conditions were done to assess the control capacities of selected parasitoids Aulacorthum solani was parasitized by Aphidius ervi, Aphidius matricariae, Ephedrus cerasicola and Praon volucre with parasitism rates ranging from 24% to 51%. Rhodobium porosum was only parasitized by A. ervi and Aphelinus abdominalis at a rate from 1.6 to 7% while C. fragaefolii was parasitized by P. volucre and E. cerasicola. Cage experiments showed that the parasitoid species selected on the basis of these experiments are well able to significantly reduce the aphid population.

85-90

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Experience-validated practical tips for IPM on protected crops and how to improve sharing and adoption of IPM knowledge
Neil Helyer, Irene Vänninen

Abstract: The Sustainable Use Directive (2009/128 EU) came into force throughout the European Union on 1st January 2014 taking IPM techniques to the forefront of pest and disease control for agriculture and horticulture producers. There is a wealth of scientific information on the individual elements of biological control, but much of this, particularly in high end refereed journals, is not picked up by the grower users. Many growers and other users of IPM still fail to make the best use of basic IPM techniques. IPM brings together all aspects of pest control as the epitome of various techniques. There is a need to get this information across to users in simplified, practical terms. This paper will illustrate various IPM techniques that in our experience still are not used optimally by growers and raises the question: What should we, as IPM advisors, consultants and researchers do differently in order to better reach our clients to improve their IPM practice at the grassroots level?

91-96

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Screening of three phytoseiid mite species as biocontrol agents of Echinothrips americanus
Hans Hoogerbrugge, Kirsten Oude Lenferink, Yvonne van Houten, Karel Bolckmans

Abstract: In this study 3 phytoseiid mite species were evaluated as biological control agents of Echinothrips americanus. The oviposition and predation rate of Amblyseius swirskii, Amblydromalus limonicus and Euseius gallicus were compared in a laboratory experiment. Moreover, A. swirskii and A. limonicus were compared as control agents of E. americanus on sweet pepper and rose plants in semi-field experiments. In the laboratory study A. swirskii showed a higher predation and oviposition rate than A. limonicus, while E. gallicus did not predate the first instar larvae of E. americanus and was therefore excluded from the semi field experiments. In the semi field experiment on sweet pepper plants the control of E. americanus was better with A. limonicus while A. swirskii built up a higher population. On rose plants, there was no difference between the two phytoseiid species.

97-101

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Control strategies against Tuta absoluta in tomato greenhouses
Barbara L. Ingegno, Sandro Frati, Luciana Tavella

Abstract: Tuta absoluta (Lepidoptera: Gelechiidae) is an exotic pest very challenging to control. For a sustainable pest control, alternative approaches, including biological control, must be pursued. Therefore, laboratory, semi-field, and field trials were conducted in 2011-2012 to evaluate different control measures against T. absoluta and their side effects on predatory mirids (e.g., Dicyphus errans). In particular, Bacillus thuringiensis, emamectin benzoate, rynaxypyr and spinosad were tested and compared with the untreated control, and in the field also with the release of Macrolophus pygmaeus. In laboratory, rynaxypyr and B. thuringiensis were the most and the least effective against all instars larvae, respectively. In semi-field conditions, numbers of eggs laid by T. absoluta females on tomato plants, treated and untreated, were not significantly different, while the highest and the lowest numbers of larvae emerged on tomato plants treated with B. thuringiensis and rynaxypyr, respectively. In the field, the lowest population levels of T. absoluta were found in the rynaxypyr treatment in both years. However, all the tested insecticides could reduce the infestations of tomato borer without any evident side effects on the two predatory mirids D. errans and M. pygmaeus sampled on tomato plants during field surveys.

103-110

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Too scared to eat: non-consumptive effects of predatory mites reduce plant damage by Western flower thrips larvae
Sarah Jandricic, Steven D. Frank

Abstract: The efficacy of biological control agents is a combination of pest consumption and effects on pest behavior and fitness. We examined non-consumptive effects of predatory mites on Western flower thrips by exposing 2nd instar larval thrips, which are too large for mites to kill, to adult Amblyseius cucumeris. Larval feeding time was reduced by 30% with mites present; leaf damage was reduced by almost 40%. To determine if intimidation by mites made thrips more susceptible to soil applications of nematodes, plants infested with 2nd instar thrips were treated with the biocontrol agents in a factorial design, and adult emergence was assessed. The mere presence of mites reduced adult thrips abundance, but there was no synergistic effect with nematodes. Since only 1st instar thrips are susceptible to mite predation, non-consumptive effects of predators deserve further study for their ability to reduce the fitness of other life stages and the damage they cause.

111-115

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Silicon supplementation: effects on chrysanthemum growth, leafminer populations, and parasitism
Daniel Klittich, Michael Parrella

Abstract: With increasing regulation of pesticide use and a growing number of independent sustainable agricultural certification services fueled by the general public's desire for less pesticides, alternative pest management strategies are needed. It is well known that nutrient management can influence pest populations. The purpose of this study was to assess the effect of silicate (Si) supplementation on chrysanthemum (mum) growth and Liriomyza trifolii population development compared to standard fertilization. The impact on successful parasitism by Diglyphus begini (Hymenoptera; Eulophidae) was also investigated. Si treated mum plants received 500 ppm of Si in the form of liquid potassium silicate with every irrigation. A control for potassium was provided using an equivalent potassium sulfate solution. Liriomyza trifolii and the D. begini were present in the greenhouse throughout the trial. Mum stem caliper was found to be the same across all treatments. Plant height was reduced in Si treated plants by 10%. In Si treated plants there was a mean reduction of 54% in mining. The number of parasitoids was too low for a meaningful evaluation. This will be repeated with the inundative releases of parasitoids into the greenhouse.

117-119

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Olfactory conditioning of natural enemies: potential benefits for pest control in greenhouse crops
H. Marjolein Kruidhof, Hans M. Smid, Andra Thiel, Thomas S. Hoffmeister and Louise E. M. Vet

Abstract: Inconsistent results in augmentative biological pest control may not only result from variation in the greenhouse environment or the genetic composition of natural enemy (NE) populations, but likely depend to a large extent on the behavioural state of the NEs. Nowadays, it is widely acknowledged that arthropods greatly rely on learning for optimizing a wide variety of life activities. However, in spite of the vast body of theoretical and empirical literature dealing with learning in NEs, this knowledge has thus far rarely been exploited for manipulating the efficacy of augmentative biological pest control. In this opinion paper we will give a short overview of the most important concepts of learning in NEs, and subsequently explore under which circumstances olfactory conditioning of adult NEs has most potential to improve pest control in the greenhouse.

121-126

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Optimizing biological control of mealybugs with lacewing larvae
Ada Leman, Roland Vijverberg, Gerben J. Messelink

Abstract: The citrus mealybug Planococcus citri (Risso) is a major pest species in ornamental crops in greenhouses. The decreased use of broad-spectrum pesticides seems to be related to an increase of mealybug infested greenhouses. Biological control with specific parasitoids and predatory beetles is not always effective and often considered as too expensive. In this study we explored the possibilities to use lacewing larvae for controlling mealybugs in ornamental greenhouse crops. We compared two species of the carnea-group of Chrysoperla green lacewings: Chrysoperla lucasina (Lacroix) and the commercial species Chrysoperla carnea s.str. (Stephens). Larvae of C. carnea s. str. were not able to complete their larval development when feeding exclusively on mealybugs, whereas half of the larvae of C. lucasina developed successfully until the pupal stage. Moreover, second instar larvae of C. lucasina consumed significantly more mealybug larvae than C. carnea s. str., suggesting that C. lucasina is more suitable for mealybug control. We further tested whether alternative prey or food source affects the control of the citrus mealybug by larvae of C. lucasina. Sterilized eggs of Ephestia kuehniella Zeller appeared to be an excellent food source for larvae of C. lucasina as shown by the fast developmental time and low mortality of larvae when feeding on this prey. The addition of the prey mite Acarus siro (L.) seemed to supplement the diet of mealybugs, resulting in an increased larval developmental rate of C. lucasina. A greenhouse trial showed a slightly better mealybug control by lacewing larvae with supplemental prey mites. However, adding Ephestia eggs as a superior food distracted the lacewings from their target prey, thereby reducing the control of mealybugs.

127-131

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Broad mites activate jasmonic acid biosynthesis genes in azalea
Gil Luypaert, Ellen De Keyser, Els Mechant, Johan Van Huylenbroeck, Jan De Riek & Patrick De Clercq

Abstract: In Rhododendron simsii hybrids or pot azaleas, damage caused by broad mites has become an increasing problem in recent years. Therefore, new strategies to control broad mites are currently investigated. One potential new strategy consists of eliciting induced resistance in pot azalea by applying the natural hormone jasmonic acid (JA) or a synthetically produced derivate. Here we present the first results in which we show induction of JA biosynthesis genes after application of chemical inducers or during broad mite infection. Furthermore, in preliminary experiments we evaluated the direct effect of JA induction on the broad mite in the laboratory.

133-136

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Three-step broad mite detection protocol as an IPM-tool in pot azalea
Els Mechant, Els Pauwels, Gil Luypaert, Bruno Gobin

Abstract: The broad mite Polyphagotarsonemus latus Banks (Acari: Tarsonemidae) is an important pest in ornamental plants like pot azalea Rhododendron simsii hybrid Planch. As the biology, physical properties and behaviour of P. latus hinder detection, the pest is often identified when malformation of flower buds and terminal leaves have already caused severe economic losses. Consequently, growers call for a reliable scouting method, allowing early broad mite detection. In addition, efficiency of (chemical) control of P. latus recently became more important, as the number of available acaricides is decreasing while acaricide resistance is increasing. To optimize the efficacy of broad mite control within an integrated pest management (IPM) strategy, a better understanding of the pest biology and dispersion within the crop is needed. Indeed, the development of an adequate sampling and isolation protocol is essential to obtain consistent and reproducible data necessary to determine treatment thresholds, optimal timing of treatments and preventive measures. Although a variety of methods for extracting broad mites from plants are described, a standardized quantitative protocol for sampling and isolation was lacking. Recently, a novel protocol for broad mite detection was developed (Mechant et al., 2014). This three-step detection protocol for P. latus on R. simsii consists of (1) sampling of shoot tips, (2) isolation with ethanol 70%, and (3) broad mite counting facilitated by vacuum filtration. In this paper, we discuss the validation of this protocol under different climatic conditions and its potential for early broad mite detection in practical conditions. Results indicate that the three-step detection protocol is suitable for replicated sampling of P. latus on R. simsii in an experimental environment as well as for reliable scouting in a grower environment, regardless of climatic conditions. Hence, the three-step detection protocol can serve as an IPM-tool for broad mite control in pot azalea.

137-142

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Persistent and emerging pests in greenhouse crops: Is there a need for new natural enemies?
Gerben J. Messelink

Abstract: Although many pest species can be controlled successfully with natural enemies (NEs) in greenhouse crops, damage caused by a few persistent pests can still not be reduced sufficiently through the use of NEs alone. Moreover, new pests continue to emerge either through the invasion of exotic species (global trade, global warming), or because less and more selective pesticides are used. In this paper I summarize the currently most problematic and emerging pest species in greenhouse crops as well as the new releases of commercialised NEs of the last 5 years. Both the need to find new NEs and methods to enhance their performance and establishment in greenhouse crops are discussed.

143-150

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The effect of relative humidity and temperature on predator release from an Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) breeding sachet
Audun Midthassel, Ian H. Baxter, Ward Stepman, Amélie Boullenger

Abstract: Environmental conditions in a protected crop can vary widely depending on weather, season, geographic location, crop type and cropping structure. The establishment of a predatory mite population and its efficacy at controlling the target pest depend on the environmental conditions in the crop. Temperature and relative humidity (RH) are important factors influencing the population increase of the predator and therefore the numerical advantage over the pest. Predatory mite breeding sachets spend several weeks in a crop and their performance will be affected by abiotic factors, thus impacting the predator output from the sachet. In order to investigate the impact of temperature and RH on predator release, sachet trials were conducted under controlled environmental conditions comparing constant temperature and RH at different levels. Amblyseius swirskii breeding sachets, with Suidasia medanensis as prey, were placed on sticky traps which were changed three times per week for five weeks. Temperature and RH were found to influence the predator release profile and the total number of mites released, indicating that the performance of a breeding sachet not only depends on its initial composition but also the climatic conditions in the target crop.

151-155

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Optimization of pest control by the predatory bug Macrolophus pygmaeus in greenhouse tomato production
Rob Moerkens, Els Berckmoes, Veerle Van Damme, Sjoerd van den Broecke, Lieve Wittemans, Hans Casteels, Luc Tirry, Patrick De Clercq, Raf De Vis

Abstract: Macrolophus pygmaeus (Rambur) (Hemiptera: Miridae) is the most important beneficial insect in greenhouse tomato production. This generalist predator is capable of controlling several pest species like whiteflies, aphids, mites, thrips and several Lepidoptera. However, as the population densities build up very slowly after release in the greenhouse, chemical interventions are often required to control early pest infestations. Faster population development would enhance biological control.
In a first study, we tested the hypothesis that M. pygmaeus populations do not build up in the winter months. Results illustrated that M. pygmaeus is actually able to develop and reproduce in December, January or February under semi-commercial and commercial conditions.
In a second study, we checked the hypothesis that high release rates of M. pygmaeus should be avoided as this might lead to adverse interactions like cannibalism. No such effects were found. We do however advise that M. pygmaeus should be distributed throughout a production area to enhance prey-finding and avoid negative inter-guild interactions.

157-162

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Grower adoption of biological control in greenhouse ornamentals and the role of technology transfer
Graeme Murphy

Abstract: The greenhouse ornamentals industry in Ontario, Canada uses biological control widely as its primary pest management strategy. Reasons for the high rate of adoption are many, but this paper focuses on the pathway of technology transfer from research to adoption, and the role of growers in the research process. Discussion is supported by examples of adopted research in Ontario.

163-167

5.00 €

 

Induced resistance in crop protection: an overview
Adrian C. Newton, Nicola Holden, Daniel De Vega Perez, Clement Gravouil, Dale R. Walters

Abstract: Induced resistance has great potential as an effective and environmentally benign means of crop protection. It exploits a plant’s own defence mechanisms, enhancing its ability to resist infection or damage by controlled application of substances that signal biotic or abiotic challenges. Defence elicitation should be proportionate to the threat, ideally priming the plant’s recognition mechanisms to respond faster to actual threats when they are detected. Thus there will be trade-offs if defence is induced unnecessarily. Resistance elicitors can be plant hormonal substances, synthetic compounds or biologically-derived molecules, often cell wall components. They may be used singly, in combination or integrated with conventional crop protectants, the latter at reduced rates. Biotrophic and necrotrophic pathogens can respond differentially to different elicitors and susceptibility can be induced too and therefore for the hemi-biotrophs it is particularly difficult to predict control levels. Host plant genotypes can respond very differently not only at species and genus level but also between cultivars. Efficacy is further dependent on the plant’s physiological state, and many environmental factors and thus nutrition, formulation and adjuvants may have large effects. Until now, in less controlled environments resistance elicitors have generally failed to deliver their full potential. However, they have the potential to change crop protection approaches substantially to manage the microbial environment, enhancing beneficials whilst containing the impact of detrimental organisms, rather than killing broad functional or taxonomic groups. Furthermore, seed produced from such crops have the potential to be more resistant and vigorous through microbial and epigenetic effects.

169-174

5.00 €

 

People and the pest: combining bioecological and social approaches to whitefly management in a greenhouse cluster
Irina Ovčarenko, Irene Vänninen, Leena Lindström, Emily Knott, Kari Saikkonen

Abstract only

175-176

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Plant feeding phytoseiids and implications for their implementation in IPM
Eric Palevsky

Abstract: Generalist phytoseiid mites are strongly associated with their plant hosts and rely on the latter for shelter against predators, suitable climatic conditions for oviposition sites, plant based foods and an assortment of prey. Additionally species from numerous genera feed directly from the plant. Recently generalist phytoseiids, amongst them plant feeders, have been introduced as control agents in the greenhouse industry, coupled with the provision of alternate foods. In this short review I present some examples of plant feeders and discuss the implications of utilizing these predators as biocontrol agents in cropping systems.

177-181

5.00 €

 

The zoophytophagous predator Macrolophus pygmaeus induces plant-mediated effects on its herbivorous prey
Maria L. Pappas, Anke Steppuhn, Daniel Geuss, Nikoleta Topalidou, Aliki Zografou, Arne Janssen, Maurice W. Sabelis and George D. Broufas

Abstract only

183-184

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Symbiont dynamics and life history impacts in adult citrus mealybug following short-term heat stress
Jasmine F. Parkinson, Bruno Gobin, and William O. H. Hughes

Abstract only

185

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Integration of beneficials and pesticides in the greenhouse: separating myth from reality
Michael P. Parrella, Danny S. Klittich and Robert L. Starnes

Abstract: The concept of integrating natural enemies and pesticides into a practical IPM program dates back to some of the original ideas that framed the development of the IPM paradigm (Stern et al., 1959). The IOBC recognized the need for this when it formed the working group (WG) Pesticides and Beneficial Organisms in 1974 'to identify selective pesticides for beneficial arthropods and to promote their use, in order to enhance biological control in plant protection...' With this WG as a driver, numerous publications and data bases (both public and private) have been developed on the side effects of pesticides. The question to ask is "Have these data and databases made a difference in terms of the practical combined use of natural enemies and pesticides in the greenhouse environment? Clearly they promote the use of more 'selective' products, but are these really being integrated with natural enemies? In 2000, Van Lenteren stated 'greenhouse crops will be produced without the need to use conventional pesticides in the very near future'. We are far away from that goal, especially in greenhouses devoted to production of ornamental crops. The increased focus on the development of biopesticides has presaged an era with greater hope for compatibility with natural enemies but this is falling short of expectations. In 2011, biopesticides accounted for < 10% of total pesticide use in California agriculture. The future still looks encouraging for these products, but there is a long way to go (Glare et al., 2012). We have taken a 'field' approach to evaluate compatibility by examining endemic natural enemies that move into California greenhouses. The premise is that in the absence of sprays, or where less offensive sprays are applied, there should be larger populations of this endemic fauna in greenhouses. Our focus is on a predatory fly (Coenosia attenuata Stein) and an obligate powdery mildew predator (Psyllobora vigintimaculata Say); other natural enemies are also being surveyed.

187-190

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Euseius gallicus, a bodyguard for roses
Juliette Pijnakker, Amandine de Souza & Felix Wäckers

Abstract: In 2014 more than 70% of the Dutch rose growers practice Integrated Pest Management. The successes booked with Phytoseiulus persimilis against spider mites [Tetranychus urticae (Koch)] have greatly contributed to this development. However, the presence of Western Flower Thrips [Frankliniella occidentalis (Pergande)] remains a bottleneck. Due to the low pest density in roses, the inundative releases of predatory mites don’t result in good colonization and thus fail to provide effective preventative control. Cosmetic damage to flower buds and petals caused by the pest are the result. A strain of the phytoseiid mite Euseius gallicus Kreiter & Tixier was collected in January 2013 in a commercial rose crop and has shown to be a promising control agent. In a cage experiment, E. gallicus could survive on rose plants and reduce thrips density and damage. A series of trials in greenhouse grown roses demonstrated that the predator in combination with pollen (Nutrimite) establishes better under field conditions than the commonly used predator Amblyseius swirskii (Athias Henriot). High densities of Euseius gallicus were obtained within six weeks in absence of prey and populations persisted as long as pollen was applied. Repeated inundative introductions of predators were no longer required. The use of E. gallicus with pollen is the first commercial strategy in ornamentals offering year-round protection against pests.

191-195

5.00 €

 

Combined use of biological control agents on ornamentals: two case-studies
Alberto Pozzebon, Andrea Boaria, Carlo Duso

Abstract only

197

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Will opening of greenhouses affect the presence of thrips pests and their antagonists on ornamentals?
Alberto Pozzebon, Andrea Boaria, Carlo Duso

Abstract only

198

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Mixing prey with pollen is advantageous for the predators Amblydromalus limonicus and Amblyseius (Typhlodromips) montdorensis
Konstantinos Samaras, Maria L. Pappas, Vassiliki Mantali, George D. Broufas

Abstract only

199-200

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Non-consumptive intraguild interactions and their relevance to biological control
Peter Schausberger

Abstract: The effects of intraguild predation (IGP) on biological control are strongly species- and context-dependent, ranging from negative to neutral to positive, requiring case by case scrutiny. To allow proper predictions of the relevance of IGP in a given setting, detailed knowledge of the direct and indirect intra- and extra-guild interactions, incl. how they ultimately affect the basal resource, the plant, is needed. Accordingly, there exist numerous studies on IGP between biological control agents. However, a common shortcoming in the understanding of the relevance of IGP in biological control is the almost exclusive focus on the consumptive (density-mediated) effects of IGP, largely disregarding non-consumptive (trait-mediated) intraguild effects. Non-consumptive predator effects modulate the behavior, physiology and morphology of prey, and translate into significant trait-mediated shifts in population and community structure and dynamics. Using predatory mite guilds as cases in point, I argue that, analogous to classical predation, trait-mediated effects of IG predators on IG prey may influence the outcome of biological control at least as strongly as do density-mediated IG effects.

201-204

5.00 €

 

Effect of release rate and odour cross-contamination for semiochemical baited traps used in thrips pest management
David A. J. Teulon, Melanie M. Davidson, Ruth C. Butler, Mette-Cecilie Nielsen

Abstract: To minimise the effects of a confined space and interference from plant floral odours found in greenhouses, two outdoor assays were undertaken to examine the effect of different release rates of methyl isonicotinate (MI), a common active ingredient of commercial thrips lures, on thrips capture in white water traps. There was a clear relationship between odour release and onion thrips capture: trap capture increased with increasing release rate. A possible effect of odour contamination between traps with different amounts of MI (including those with none) may be greater than previously thought and suggests that previous work may have underestimated the ability of semiochemicals to increase trap capture.

205-210

5.00 €

 

Pesticide treadmill in greenhouses of Kazakhstan: Why IPM is not adopted?
Kazbek Toleubayev

Abstract: This paper reveals the major reasons why Integrated Pest Management, including biological pest control, is not adopted and why pesticides are indiscriminately used in greenhouse farms in Kazakhstan. In 2012-2013 we carried out monitoring of pest occurrence in 49 greenhouse farms, with total area of more than 200 ha, located in various regions of Kazakhstan. Data related to the pest and pesticide problems were obtained through in-depth interviews, participant observation method, literature and press coverage review with cross-checking the data from these sources. It appears that in greenhouses problems related to arthropod pests are topical, causing significant yield losses. It was observed that pesticides are used injudiciously, leading to many consequent problems. This paper concludes that IPM-based pest control needs to be incorporated into everyday farming routines through explicitly knowledge-based plans for action.

211-214

5.00 €

 

Artificial diets support the development and reproduction of the predatory mite Amblyseius swirskii
Nguyen Duc Tung, Dominiek Vangansbeke, Patrick De Clercq

Abstract: Liquid meridic artificial diets, lyophilized forms of these liquid diets and solid meridic artificial diets supplemented with pupal hemolymph of Antheraea pernyi (Guérin-Méneville) or with Artemia franciscana Kellogg (Anostraca: Artemiidae) cysts were tested for Amblyseius swirskii (Athias-Henriot) (Acari: Phytoseiidae), an important biological control agent of whiteflies, thrips and broad mites in several greenhouse crops. The liquid artificial diets and freeze-dried liquid diets supported the development and reproduction of A. swirskii. Freeze-drying of liquid diets did not affect their acceptability and nutritional quality for the mite. Amblyseius swirskii had no difficulty handling and feeding on powdered, solid artificial diets, allowing the predator to develop and reproduce successfully for at least a single generation. These findings indicate the potential of artificial diets to rationalize the mass production of the phytoseiid. Dry diets should have better potential for use as supplemental foods to sustain predatory mite populations in the crop after release.

215-218

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Control of the invasive leafminer Tuta absoluta by leaf application of entomopathogenic nematodes
Veerle Van Damme, Rob Moerkens, Els Berckmoes, Lieve Wittemans, Raf De Vis, Bert Beck, David Nuyttens, Hans Casteels, Luc Tirry, Patrick De Clercq

Abstract only

219

0.00 €

 

Antipredator behavior of thrips towards phytoseiid eggs: overrated or underestimated?
Dominiek Vangansbeke, Duc Tung Nguyen, Joachim Audenaert, Ruth Verhoeven, Luc Tirry, Bruno Gobin & Patrick De Clercq

Abstract only

220

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Food supplements for Amblyseius swirskii: supporting predator or prey populations?
Dominiek Vangansbeke, Duc Tung Nguyen, Joachim Audenaert, Ruth Verhoeven, Luc Tirry, Bruno Gobin & Patrick De Clercq ............................

Abstract: In order to reduce the cost of repeated introductions of natural enemies in protected crops, food supplements can be provided when target prey levels are low. However, selecting such foods should be done with extreme care, as some omnivorous pests may also benefit from those resources. Western flower thrips, Frankliniella occidentalis Pergande (Thysanoptera: Thripidae) is such an omnivorous herbivore feeding on both plant and animal materials. In the present laboratory study, we tested three supplemental foods used in protected cultivation to support populations of the phytoseiid predators: pollen of narrow-leaved cattail Typha angustifolia L. (NutrimiteTM), dry decapsulated Artemia franciscana Kellogg (Branchiopoda: Artemiidae) cysts of high quality, and a commercial product consisting of decapsulated cysts of Artemia sp. (Artefeed). The value of these supplemental foods for sustaining population growth of the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) and its prey F. occidentalis was investigated. Furthermore, we assessed the impact of the presence of the supplemental foods on the predation efficacy of A. swirskii on first instars of F. occidentalis. Results showed that the foods differentially affected population growth of both pest and predator. Thrips performed better on pollen than on Artemia cysts when provided on bean leaves (Phaseolus vulgaris L.). Similarly, when fed on T. angustifolia pollen, the population growth rate of A. swirskii was higher than on both types of Artemia cysts.

221-226

5.00 €

 

Facilitation of predatory mite movement in tomato enhances the control of tomato russet mites
Renata van Holstein-Saj, Gerben J. Messelink

Abstract only

227

0.00 €

 

Hunting for innovation places to improve risk management of quarantine pests by greenhouse ornamental producers
Irene Vänninen, Niina Kangas, Anne Lemmetty, Isa Lindqvist

Abstract only

228

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Preventive versus curative releases of mirids to control Myzus persicae in sweet pepper
Jeroen van Schelt, Hans Hoogerbrugge, Karel Bolckmans, Livia A. Sidney, Vanda H. P. Bueno, Chantal Bloemhard , Gerben J. Messelink

Abstract: In this study we compared four species of mirid predatory bugs: Macrolophus pygmaeus, Dicyphus tamaninii, Dicyphus errans and Dereaocoris pallens on their potential as biocontrol agents of aphids in sweet pepper. Their population development on Myzus persicae was assessed in cages on flowering sweet pepper plants as a curative treatment and when released preventively. Preventive releases on pepper plants were tested without and with additional food (Ephestia kuehniella eggs and Artemia franciscana cysts). The best control of aphids was achieved with M. pygmaeus and D. tamaninii when released preventively in the treatments with supplemental food. None of the mirid species was able to control aphids when released curatively. Additional experiments on Petri dish level showed that M. pygmaeus, D. errans and D. pallens were all able to develop on a diet of aphids and to produce eggs. However lowest mortality during development and highest oviposition rate on a diet of aphids were obtained with M. pygmaeus, which confirmed the result of the greenhouse trial.

229-234

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Fytotoxweb: online database of Belgian trial results with plant protection products in ornamental plants
Marc Vissers, Joachim Audenaert, Bruno Gobin

Abstract: The high diversity of ornamental plants and the market’s zero tolerance for leaf damage requires sufficiently effective plant protection products and a good knowledge about potential phytotoxic effects of spray applications. We perform yearly trials at both registration (EPPO) and screening level to ensure that growers have adequate information on the risks of specific products to specific plant cultivars. This information is collated into a searchable database to allow easy access for growers.
Data was collated from replicated efficacy trials, side effect trials and annual screening trials of the PCS. In a screening trial, all growers of potted plants and bedding plants are asked to send in currently grown cultivars. In this way, growers quickly obtain information on the use of the newest compounds on their own plant species. Yearly, about 10 chemical compounds were screened on 50 up to 100 plant species.
All these trials generated a mass of information which made it necessary to develop a tool by which the test results can be found quickly. ‘Fytotoxweb’ was created as a web page for the growers of indoor ornamental plants, with the aim to easily find all our test results by searching by product name or plant name.
Consultations on this website provide the following trial information for each ‘plant/product combination’: visible crop damage, growth retardation or spray residue, and since 2014 also efficacy and side effect results; all these data are based on results of the PCS research station. In addition background information of the relevant trial details are displayed: the plant size, number of treatments, spray dosage, climate data, the names and contact information of the responsible researchers etc.
This website was originally created for growers, but other interested parties such as advisers, researchers, producers and authorization holders of plant protection products, can consult ‘Fytotoxweb’, too. Access to the database requires PCS membership.

235-238

5.00 €

 

An uncommon pest on spinach in a glasshouse in Belgium
Johan Witters, Nick Berkvens, Raf De Vis, Hans Casteels

Abstract only

239

0.00 €

 

Parasitus americanus and Coenosia attenuate: natural enemies of Collembola and Sciaridae in lettuce crops in Flanders (Belgium)
Johan Witters, Bie Verbruggen, Ilse Leenknegt, Raf De Vis, Hans Casteels

Abstract only

240

0.00 €

 

Reproduction of Nesidiocoris tenuis reared on Ephestia kuehniella eggs and Bemisia tabaci nymphs
Eizi Yano, Miku Nakauchi, Hiroshi Watanabe, Shun Hosaka, Yusaku Hayashi, Norihide Hinomoto

Abstract: A project aimed at developing an augmentative biological control programme for Bemisia tabaci (Gennadius) and Thrips palmi Karny using an indigenous strain of Nesidiocoris tenuis (Reuter) is under way in Japan. As a fundamental part of this project, the development, survival and reproduction of N. tenuis were studied in the laboratory using Ephestia kuehniella Zeller eggs and B. tabaci nymphs as diets. Both diets were provided on tomato leaf sections to study immature development and survival. Tomato leaflets with petioles were used as oviposition substrates in oviposition experiments. For immature stages reared on E. kuehniella eggs, development time and survival rate at 25 °C were similar to those of the Spanish strain studied previously. The daily oviposition rate of the Japanese strain was greater than that of the Spanish strain. For immature stages reared on B. tabaci nymphs, development time at 25 °C was longer than that of those reared on E. kuehniella eggs. The fecundity of female adults reared on E. kuehniella eggs was greater than that of those reared on B. tabaci nymphs. However, when the predator was fed B. tabaci nymphs, its intrinsic rate of natural increase was greater than when it was fed E. kuehniella eggs. The lower developmental threshold and the thermal constant were estimated based on the developmental times for N. tenuis reared on B. tabaci nymphs at 20 °C, 25 °C and 30 °C. The lower developmental threshold was much higher than that of the Spanish strain. In conclusion, B. tabaci nymphs are as suitable as E. kuehniella eggs as diets for the successful reproduction of N. tenuis.

241-244

5.00 €

 

Intra- versus inter-specific interactions of Μacrolophus pygmaeus and Nesidiocoris tenuis foraging on an aphid population
Maselou, D., D. Perdikis and A. Fantinou

Abstract: The nature of antagonistic/synergistic interactions among predators sharing common prey patches has been widely reported to play a major role in biological control. This study focuses on the effects of prey availability on the predation rate of two predators: Μacrolophus pygmaeus and Nesidiocoris tenuis (Hemiptera: Miridae) when foraging alone or together under different prey density levels. Intraspecific and interspecific interactions were tested by introducing either a conspecific or heterospecific pair into a dish with an eggplant leaf where 2nd instar Myzus persicae nymphs were present as prey. Prey densities of 4, 12, 20, 24, 32 and 40 were used and consumption was recorded after 24 h. Functional responses of each predator species were evaluated. We also simultaneously employed both the multiplicative and substitutive design to test the independent and combined effects of the two predatory species. According to the outcomes, both predators exhibited a Type II functional response with Μ. pygmaeus satiated at comparatively lower prey density than N. tenuis. Emergent multiple predator effects were largely absent in this system, since the outcomes were consistent with the expected combined effects of these two predators. This is likely due to partial spatial separation of these predators when foraging in a common habitat.

245-251

5.00 €

 

Validation of a decision support tool for integrated control of Bremia lactucae in greenhouse lettuce
Aaike Bogaert, Nathalie Van Hese, Tom Beyers, Peter Bleyaert, Isabel Vandevelde & Monica Höfte

Abstract: Downy mildew caused by Bremia lactucae is a major threat to lettuce production. Infected leaves show chlorotic spots and under humid conditions sporulating mycelium, making the entire head of lettuce unmarketable. Currently, growers rely largely on fungicides applications according to a fixed schedule to control this disease. In an effort to reduce the number of fungicide applications a decision support system (DSS) was developed. This DSS is driven by the greenhouse climate data and input of information from previous fungicide applications. In short, the DSS determines whether climate conditions are favorable for infection and/or sporulation by B. lactucae at any given moment and if the lettuce crop is still protected by a previous preventive treatment. If not, a warning is send to the user with the suggestion of a suitable fungicide, based on the history of prior applications and empirically determined data on fungicide efficacy. The aim of the current study was to validate the DSS by comparing the incidence of B. lactucae infections on lettuce heads treated according to the conventional fixed spray schedule and according to the warnings of the DSS. Our data suggest that a comparable number of fungicide applications is required when following the fixed schedule and the DSS. However, when following the DSS efficacy of the applications could be increased. Although further optimization of the DSS is recommended, it is expected to become a valuable instrument in pursuing a more rational use of fungicides.

253-258

5.00 €

 

Efficacy of commercial and non-commercial strains of entomopathogenic fungi
against the peach aphid Myzus persicae (Sulz.)

Mihaela M. Dinu, Ada Leman, Gerben J. Messelink

Abstract: The efficacy of twenty-two strains of entomopatogenic fungi, isolated from natural outbreaks and also from commercial products (Lecanicillium (Verticillium) lecanii (Zimm.) Zare & Gams, Lecanicillium longisporum (Petch) Zare & W. Gams, Beauveria bassiana (Bals.-Criv.) Vuill, Metarhizium brunneum (anisopliae) (Metschn.) Sorokin, Isaria fumosorosea Wize, Paecilomyces lilacinus (Thom) Samson, Hirsutella kirchneri (O. Rostr.) Minter, B. L. Brady & R. A. Hall and Hirsutella thompsonii F. E. Fisher), was tested for the control of the peach aphid Myzus persicae (Sulz.). Pathogenicity of the selected isolates was first evaluated through a quick screening test: aphids were exposed to conidia for 5 minutes, by gently transferring them to sporulated cultures (on PDA), and then transferred to plastic boxes (detached leaf bioassay) and kept at 20 °C, 80% RH for 10 days. Signs of infections were assessed daily. The most virulent strains were selected for the next step, the laboratory trial. For effectiveness of strains in the laboratory trial, conidiospores in three different doses (105, 107, 109 conidia/ml) were sprayed on aphids. Treated aphids were kept to detached leaves of sweet pepper on 1% water agar for pathogen incubation and pathogenicity of most fungal species was confirmed at all the three doses. The most virulent strains were tested in greenhouse, on aphids reared on potted plants. All the tested strains gave significant control of aphid in the laboratory trial, but only Lecanicillium longisporum (Vertalec® isolate) showed a reasonable control of aphids in greenhouse trial with infection rates up to 40%. An increasing trend in mortality of aphids (epizootic) was observed in all the treatments with an increase in aphid population.

259-264

5.00 €

 
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