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IOBC-WPRS Bulletin Vol. 103, 2014


IOBC-WPRS Bulletin Vol. 103, 2014

Working Group "Pesticides and Beneficial Organisms".
Proceedings of the meeting at Gembloux (Belgium), 25 - 27 February, 2014.
Edited by Jean-Pierre Jansen.
ISBN 978-92-9067-284-5 [XI + 71 pp.]


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Side effects of entomopathogenic nematodes on beneficial arthropods in pome fruit and the role of adjuvants on their selectivity
T. Belien, S. Huysecom, N. Berkvens, N. Viaene, W. Keulemans & D. Bylemans

Abstract: Entomopathogenic nematodes (EPN) are increasingly being used as biological control of insect pests. Current applications are almost exclusively soil treatments, principally targeting soil-borne insect pests. However, the soil also harbours beneficial arthropods and less is known about the effects of EPNs on these soil-borne beneficial arthropods. Furthermore, there is a rising interest in their control potential of aboveground pests. Such aboveground treatments covering the crop with EPNs could also affect beneficial arthropods present on leaves and/or stem. In this study we investigate the side effects of EPNs (Steinernema carpocapsae, Steinernema kraussei, Heterorhabditis bacteriophora and Phasmarhabditis hermaphrodita) on two soil-borne beneficial arthropods in pome fruit, i.e. velvet mites (Allothrombium fuliginosum, Thrombidiidae) and earwigs (Forficula auricularia, Forficulidae) in laboratory trials. While S. carpocapsae and S. kraussei applied as sole treatment were only slightly to moderately harmful for both beneficial arthropods, significant increased mortality rates were obtained after EPN-treatments in combined use with adjuvant Trend90. Additionally, a field trial was carried out in which the impact of aboveground EPN treatments on several beneficial arthropods (including earwigs, predatory bugs and ladybirds) in apple was evaluated and compared to chemical references. In accordance with the laboratory trials no or only negligible side effects were obtained in absence of an adjuvant. These results demonstrate the rather safe use of EPNs in pome fruit orchards, but indicate potential side effects if EPNs are sprayed in combination.


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A large field trial to assess the short-term and long-term effects of 5 insecticides used to control the pollen beetle on parasitic hymenoptera in oilseed rape
J.-P. Jansen & G. San Martin Y Gomez

Abstract: A large scale field trial was performed in spring 2013 to assess the effects of Plenum (pymetrozine), Mavrik 2F (tau-fluvalinate), Biscaya (thiacloprid), Boravi WG (Phosmet) and Pyrinex (Chlorpyriphos-ethyl) used to control the pollen beetle Meligethes aeneus (F.) (Col.; Nitidulidae) on pest and beneficial arthropods’ populations in winter oilseed rape. The insecticides were applied at their commercial rate soon before flowering on large strips of oilseed rape (30 m x 200 m), divided into four plots of 50 m x 30 m. A strip was left untreated as control. Insects were weekly sampled with the help of beating methods and sweep net from one day to 50 days after product application. The direct effects of the products were assessed on adult pollen beetle (target pest), adult cabbage seed weevil Ceutorrhynchus obstrictus (Marsham) (Col.; Curculionidae) (secondary pest) and adult of parasitic hymenoptera related to these insects (Tersilochinae and Pteromalidae). In the context of IPM, long term effects were assess on pollen beetle larvae to determine their number, the parasitism rate and to estimate the balance of parasitic hymenoptera/pollen beetle that could be produced by the field for the next season.
Biscaya, Boravi WG, Pyrinex and Mavrik 2F were effective to control the adult pollen beetle population and had also an activity on cabbage seed weevil despite the fact that this pest only occurred 2 or 3 weeks after the application of product. Plenum was only effective to control the pollen beetle population 1 day after treatment and had no significant impact on cabbage seed weevil.
All the insecticides tested had a significant impact on adult parasitic hymenoptera population compared to the control. Plenum had limited effects while the other insecticides reduced of 59% to 72% the captures in the sweep net samplings. The main effects were observed on adult of the Tersilochinae family that are mainly specialised in the parasitism of pollen beetle larvae. Biscaya had also a significant impact on Pteromalidae captures, a family containing species specialised in the parasitism of weevils, despite the 4-week delay between the day of the treatments and the first arrival of these hymenoptera in the crop.
Biscaya significantly reduced the parasitism rate of the pollen beetle larvae, that dropped to less than 15% compared to 43.2% in the control. Pyrinex also decreased the parasitism rate with only 23% of larval parasitism, but the differences were not significant. Biscaya and, to a lesser extend Pyrinex, reduced the balance of parasitic hymenoptera/pollen beetle while Plenum, Boravi WG and Mavrik 2F led to the end of the growing season to the same ratio than the untreated control. These results suggest that the regular use of Biscaya and/or Pyrinex on a large scale before flowering is favourable to the long term development of pollen beetle populations by negatively impacting the populations of their parasitoids, despite their good short-term efficacy to control this pest.


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Compatibility of predatory mites with pesticides for the control of Thrips palmi Karny
A. G. S. Cuthbertson

Abstract: The compatibility of predatory mites (Amblyseius swirskii Athias-Henriot, Typhlodromips montdorensis Schicha, Neoseiulus cucumeris (Oudemans) and Iphiseius degenerans Berlese) with chemical pesticides was investigated for inclusion in control strategies for Thrips palmi Karny. Both 24 and 48 h assessments following application of abamectin, spinosad and imazalil demonstrated mortality of predatory mites (across all species), which was significantly higher than with the other treatments (P < 0.001). Spraying with pymetrozine did not provide any increased mortality when compared with the water control. Application of thiacloprid proved detrimental only to I. degenerans. Following indirect exposure of predatory mites to pymetrozine and imazalil, no significant differences in mite mortality were obtained. Indirect exposure to spinosad was identified as the most detrimental treatment (P < 0.001) to all mites. Abamectin also proved detrimental, with only T. montdorensis showing any potential tolerance. Compatibility with chemicals varied between the mites. The potential of incorporating the mites into eradication strategies for T. palmi is discussed.


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Evaluation of the long-term effects of tebuconazole on the parasitic wasp, Aphidius rhopalosiphi and its host, the bird cherry-oat aphid, Rhopalosiphum padi
E. Kulec-Płoszczyca, M. Czarnecka & P. Parma

Abstract: The aim of the study was to determine the long-term effects of the fungicide tebuconazole on mortality and fecundity of the parasitic wasp, Aphidius rhopalosiphi and mortality of its host, the bird cherry-oat aphid, Rhopalosiphum padi L. under laboratory conditions. The period after exposure before the insects can recolonize the plants was also determined. The adult wasps and aphids were exposed on barley plants (Hordeum sp. L.) treated with the fungicide. Tebuconazole was tested using a representative commercial formulation. The test item solution was applied to barley twice, at a 14-day interval, using a chamber sprayer. It was tested at a single rate of application, corresponding to its maximum recommended field rate. A control group (distilled water) and a group treated with a reference item (dimethoate) were also included in the study. The experiment on A. rhopalosiphi was performed according to the test method of Mead-Briggs et al. (2010), while the test on R. padi was conducted using the Institute’s own method. The mortality results prove that tebuconazole was toxic to the wasps and the aphids directly after the second treatment. It can be concluded that the recolonization of the wasp A. rhopalosiphi and the aphid R. padi on barley, treated with tebuconazole, can take place 7 days after the second treatment. The test fungicide negatively affected the wasp fecundity as the reduction in fecundity amounted to 27.3% when compared with the control group.


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A field study to assess the effects of insecticides used to control the Colorado beetle in potato on aphid antagonists
J.-P. Jansen & G. San Martin Y. Gomez

Abstract: The effects of five insecticides used to control the Colorado beetle in Potato were assessed in a field trial on aphid-specific beneficial arthropod fauna, mainly parasitic hymenoptera, ladybirds, lacewings and hoverflies. The insecticides were applied at their commercial rate at the end of July, when beneficial arthropods and aphid population were at their maximum. The effects on aphid populations were followed by visual inspection up to 33 days after treatment and aphid natural enemies were collected by the beating methods 2, 7 and 18 days after treatment.
The results of the beatings showed that all insecticides had an impact on both ladybird and hoverfly larvae. The impact on ladybird was limited for azadirachtin, rynaxypyr and spynosin B while cypermethrin and thiametoxam were more toxic. Hoverfly were more sensitive to all the insecticides tested, with population reduction > 50% compared to the control. Spynosyn B also reduced the parasitism of aphid by Aphidius wasps at DAT2, determined by dissection of aphid collected during the beatings, but the effects were limited in duration and no significant effects were observed later. The other product had no or limited effects on aphid parasitism.
The effects on aphid populations revealed that no insecticides were promoting aphid outbreak by directly impacting natural enemy’s populations. However, the beneficial arthropods activity was so high that even high reductions of populations had no impact on aphid population in this particular field site.
These results are discussed in term on beneficial populations and IPM, taking into accounts both direct effects and long-term effects.


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Importance of alternative predators of pear suckers (Cacopsylla pyri) in organic versus IPM pear orchards
K. Vrancken, H. Trekels, T. Thys, P. Demaeght, T. Van Leeuwen, P. De Clercq & T. Beliën

Abstract: Pear suckers (Cacopsylla sp. or pear psylla) are widely considered to be the most important pest in pear orchards. Sustainable control of pear psylla relies on their natural suppression by beneficial arthropods and a well-tuned integration of crop protection treatments. Predatory bugs (Anthocoris sp.) are efficient predators of pear suckers, playing a crucial role in the control of pear psylla summer generations. However, their poor presence early and late in the season and their high mobility makes it difficult for growers to build up persistent predatory bug populations in their orchards to efficiently control pear psylla the whole season. Therefore, we investigated alternative natural enemies which potentially play an important role in the suppression of pear psylla, especially during early spring and autumn. To this end, a large-scale monitoring study was executed comprising extensive samplings throughout the year in fourteen pear orchards, and comparing psylla as well as beneficial fauna population developments between organic and IPM pear orchards. Organic orchards clearly displayed a lower pear psylla pressure correlating with higher proportions of specific predator populations, in particularly velvet mite (Trombidiidae) and spider (Araneae) populations. In addition, predation of C. pyri was verified by PCR-based gut content analysis. The outcome was analyzed in light of different treatment schedules, providing insights in potential side-effects of crop protection treatments on the composition of beneficial fauna in pear orchards.


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Lethal effects of two reduced risk insecticides on Harmonia axyridis and Coleomegilla maculata (Col., Coccinellidae) following two routes of exposure
P. Cabrera, D. Cormier, M. Fournier & E. Lucas

Abstract: Reduced-risk pesticides are new compounds noted for their lower impact on human health and environment, and lower toxicity onto non-target organisms than traditional products. Novaluron (Rimon® EC 10) and chlorantraniliprole (Altacor® 35 WG), two reduced-risk insecticides, have been registered to control the codling moth, Cydia pomonella (L.) (Lep., Tortricidae), in Canada in 2008. Novaluron inhibits the chitin synthesis and belongs to the benzoylphenyl urea chemical class. Chlorantraniliprole, part of a new class of selective insecticides, the anthranilic diamides, causes paralysis of the muscle cells by interfering with the ryanodine insect receptors. Both compounds act by ingestion and contact, exhibiting ovicidal and larvicidal activities. Due to the high toxicity to codling moth and their low negative impact on the environment, novaluron and chlorantraniliprole are recommended for use in IPM programs. However, several studies have shown negative effects on beneficial arthropods. The aim of this study was to evaluate the effects of novaluron and chlorantraniliprole on two aphidophagous predators commonly found in apple orchards in south eastern Canada, Harmonia axyridis (Pallas) and Coleomegilla maculata (De Geer) (Col., Coccinellidae). We studied specifically the lethal effects of novaluron and chlorantraniliprole on larvae of H. axyridis and C. maculata following ingestion of treated prey and exposure to residues. Insecticide field rates (100 g a.i./ha novaluron and 50.75 g a.i./ha chlorantraniliprole) were tested against the predators in laboratory conditions. To evaluate the lethal effect of exposure to insecticides via ingestion, 1st instar larvae were fed with treated aphids for 24 hours. In a second bioassay, larvae were placed individually in dry Petri dishes previously dipped in insecticide solutions. Mortality was assessed at 24 h, 72 h and 6 d after start of exposure. Following ingestion of treated prey, novaluron was highly toxic for H. axyridis causing 96.7% mortality after 6 days. C. maculata was not sensitive to novaluron and none of the species were sensitive to chlorantraniliprole. Both insecticides were toxic to H. axyridis and C. maculata via contact with residues. At 6 d, Chlorantraniliprole caused 100% mortality of both species, and exposure to novaluron resulted in 100% mortality for H. axyridis and 98.9% for C. maculata.


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Effects of a commercial formulation of a plant resistance elicitor on non-target organisms
J.-P. Jansen, R. Buenotesta & B. Schiffers

Abstract: The toxicity of Fyto11, a plant resistance elicitor commercial formulation used to increase the natural resistance of Cucurbitaceae (cucumber, zucchini and melon) and Solanaceae (tomato and sweet pepper) against powdery mildew under greenhouse conditions, has been assessed on several beneficial arthropods: the honeybee Apis mellifera, the predatory mite Typhlodromus pyri, the aphid parasitic wasp Aphidius rhopalosiphi and the aphid predator Episyrphus balteatus.
Tested at 0.5% and 1.0% spray dilution on plants, Fyto11 did not lead to significant corrected mortalities for E. balteatus larvae and adult wasps of A. rhopalosiphi, with a maximum of 5.4% mortality. No effects on reproduction capacity of the parasitic wasps were observed.
The exposure of T. pyri protonymphs to Fyto11 on glass plates lead to corrected mortalities of 1.1% and 32.6% at 0.5% and 1.0% and to a reduction of female fertility of 9.0% and 25.4%, compared to the control performance. When assessed on the honeybee by contact and oral exposure, Fyto11 did not lead to significant effects, with LD50 estimated as > 10 μg a.i./bee (oral) and 12.5 μg a.i./bee (contact), leading to HQ ratio < 50 and classifying the product at no or low risk for honeybees.
These results showed that the product was harmless for all beneficials at the proposed commercial rate, except for T. pyri at 1.0% on glass plates, where the product was rated as slightly harmful. Even if all the beneficial species’ diversity has not been assessed with this product, negative effects on non-target organisms are not expected in field conditions and Fyto11 can be considered as compatible with IPM programs.


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Total effects of selected plant protection products applied to different natural substrates on the predatory mite Typhlodromus pyri Sch.
M. Czarnecka, P. Parma & E. Kulec-Płoszczyca

Abstract: Extended laboratory studies were conducted to evaluate lethal and sublethal effects of selected plant protection products (PPPs) on Typhlodromus pyri Sch. (Acari: Phytoseiidae). The endpoints of the studies were mortality after 7 days of exposure and the reduction in total egg production after 14 days. Three fungicides (thiophanate-methyl, chlorothalonil, and pyrimethanil), one insecticide/acaricide (paraffin oil), one plant growth regulator (ethephon), and three herbicides (MCPA, clopyralid + picloram, and amidosulfuron) were tested using commercial products at their maximum recommended rates. The studies were performed according to the ‘island method’ (Joisten, 2000). T. pyri protonymphs were exposed on the following natural substrates: bean (Phaseolus vulgaris), rose (Rosa L.), and blackberry (Rubus L.) treated with the PPPs with the help of the Potter laboratory spray tower on the basis of the application of 200 l of water/ha. Due to phytotoxic effects of MCPA and clopyralid + picloram, they were applied to rose and blackberry leaf discs, whereas bean leaf discs were sprayed with the remaining PPPs. A control (distilled water) and a reference item treatment were also included. Total effects (E) of the tested PPPs on T. pyri were determined by combining lethal (mortality) and sublethal effects (reproduction) using the IOBC classification. Thiophanate-methyl, chlorothalonil, paraffin oil, and MCPA appeared to be slightly harmful, whereas the remaining PPPs were found to be harmless to T. pyri. Among all the PPPs evaluated, ethephon was the most selective to the predators. None of the PPPs adversely affected the reproductive capacity of the mites. The poorest reproductive performance was caused by thiophanate-methyl (the reduction of 39.5%).


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Unnecessary pesticide applications: The need for correct identification of a beneficial mite species in Northern Irish apple orchards
A. G. S. Cuthbertson & A. K. Murchie

Abstract: Within apple orchards integrated pest management (IPM) programmes play a very important role in the control of invertebrate pests. Many current IPM strategies concentrate only on the role of a given specialist predatory species. However, generalist beneficial insects, such as several mite species, must also be fully evaluated for their potential in controlling pests. Recent research has shown that the generalist predatory mite Anystis baccarum (Linnaeus) can offer much potential in controlling invertebrate pests within apple orchards in Northern Ireland. This mite species has been confirmed as the most commonly occurring predatory mite in local orchards. However, apple growers have been mis-identifying this beneficial species as the economic pest European fruit tree red spider mite, Panonychus ulmi (Koch). As a result, unnecessary pesticide applications have been applied against what has now been confirmed to be a beneficial species. To aid apple growers in the identification of A. baccarum, identification cards have been produced and circulated around the apple growers. Positive uptake of the cards by many apple growers has resulted in the correct identification of A. baccarum from P. ulmi, and therefore, a reduction in chemical pesticide applications within the apple orchards. The benefits of encouraging A. baccarum populations within orchard ecosystems are discussed.


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