Letteratura scientifica selezionata sul tema "Anystis baccarum"

A generalist predatory mite, Anystis baccarum (L.), has been identified as a key predator of small, soft-bodied pest species in various agroecosystems around the world. The foxglove aphid Aulacorthum solani (Keltenbach) is a new problematic pest in Canadian greenhouses. Laboratory colonies of A. baccarum were established and its predatory efficacy against A. solani was assessed. In laboratory trials, A. baccarum ate approximately one adult aphid or seven first instar aphids in 24 h. In a greenhouse bench trial on sweet peppers with the free-flying aphid parasitoid, Aphidius ervi Haliday, the population dynamics of A. solani in the presence or absence of A. baccarum was evaluated. Although the parasitoid alone successfully eradicated A. solani, when A. baccarum were present on the plants, the aphid population was eradicated more rapidly. Fruit yield was also 15% higher from plants where A. baccarum was released than the control (without A. baccarum). Furthermore, plants were naturally infested by Frankliniella occidentalis (Pergande) during the trial, which caused visible feeding damage to the fruits. Anystis baccarum also predates on thrips and thrips’ feeding damage to the fruits was reduced on plants where A. baccarum was released. Anystis baccarum was able to establish in sweet peppers and was determined to be complementary to the current practice of using A. ervi for the biological control of A. solani.

The presence of some insect and mite species on kiwifruit at harvest can cause quarantine problems in some overseas markets There is potential to remove these passenger pests using physical handling methods such as the fruit brushing systems that are currently used in packhouses The abilities of two types of post harvest brushing systems to remove surface dwelling insects and mites from kiwifruit were compared Bins of naturally infested fruit were passed through two contrasting post harvest brushing systems and levels of infestations subsequently compared with unbrushed fruit Both brushing systems removed more than 85 of Collembola thrips mites and small beetles However armoured scale insects were not removed and a relatively low proportion of whirlygig mite (Anystis baccarum) cocoons was removed There were no significant differences between the two brushing systems

This study investigated commensal feeding interactions between the European harvestman (P. opilio L.) and the predatory mites Balaustium spp. and Anystis baccarum L. It also investigated the feeding behaviour of P. opilio. Experiments were conducted in the laboratory using standardised temperature, humidity, photoperiod and experimental arenas, with eggs of the brown blowfly (Calliphora stygia F.) as prey facsimiles. Due to initial difficulties in obtaining enough predatory mites, mite feeding was manually simulated piercing blowfly eggs with a minuten pin. P. opilio consumed significantly more freeze-killed than live blowfly eggs, indicating that freezing induced chemical and/or physical changes to blowfly eggs that are detected by P. opilio. Significantly more manually pierced eggs were consumed by P. opilio compared with unpierced ones, demonstrating that piercing caused a chemical and/or physical to the egg and increased the feeding rates of P. opilio. Different densities of eggs had no effect on the numbers eaten by P. opilio and placing single pierced eggs next to groups of unpierced eggs also had no effect on the numbers of unpierced eggs eaten. These results suggest that P. opilio does not exhibit klinokinesis or orthokinesis to intensify its search for prey around the area where previous prey were located. P. opilio ate significantly more brown blowfly eggs that had previously been fed on by mites, demonstrating that a short term commensal interaction existed. However, further work is required to demonstrate if the relationship is commensal in the longer term. A comparison between hand-pierced and mite-pierced eggs showed that P. opilio ate significantly more of the former indicating that mite and hand piercing were quantitatively different. The potential for, and importance of, other commensal or mutual relationships between predators in agroecosystems is discussed. The lack of klinokinesis and orthokinesis in P. opilio is compared with other predators and parasitoids that do exhibit these behaviours. The means by which prey are detected by P. opilio are discussed in relation to interpreting behaviours such as prey inspection. Concerns about the effect of pre-treatment and handling of sentinel prey and the problems of using prey facsimiles are raised.

This study investigated commensal feeding interactions between the European harvestman (P. opilio L.) and the predatory mites Balaustium spp. and Anystis baccarum L. It also investigated the feeding behaviour of P. opilio. Experiments were conducted in the laboratory using standardised temperature, humidity, photoperiod and experimental arenas, with eggs of the brown blowfly (Calliphora stygia F.) as prey facsimiles. Due to initial difficulties in obtaining enough predatory mites, mite feeding was manually simulated piercing blowfly eggs with a minuten pin. P. opilio consumed significantly more freeze-killed than live blowfly eggs, indicating that freezing induced chemical and/or physical changes to blowfly eggs that are detected by P. opilio. Significantly more manually pierced eggs were consumed by P. opilio compared with unpierced ones, demonstrating that piercing caused a chemical and/or physical to the egg and increased the feeding rates of P. opilio. Different densities of eggs had no effect on the numbers eaten by P. opilio and placing single pierced eggs next to groups of unpierced eggs also had no effect on the numbers of unpierced eggs eaten. These results suggest that P. opilio does not exhibit klinokinesis or orthokinesis to intensify its search for prey around the area where previous prey were located. P. opilio ate significantly more brown blowfly eggs that had previously been fed on by mites, demonstrating that a short term commensal interaction existed. However, further work is required to demonstrate if the relationship is commensal in the longer term. A comparison between hand-pierced and mite-pierced eggs showed that P. opilio ate significantly more of the former indicating that mite and hand piercing were quantitatively different. The potential for, and importance of, other commensal or mutual relationships between predators in agroecosystems is discussed. The lack of klinokinesis and orthokinesis in P. opilio is compared with other predators and parasitoids that do exhibit these behaviours. The means by which prey are detected by P. opilio are discussed in relation to interpreting behaviours such as prey inspection. Concerns about the effect of pre-treatment and handling of sentinel prey and the problems of using prey facsimiles are raised.

Au Québec, plus d'une vingtaine de ravageurs prépondérants et occasionnels et plus d'une dizaine de maladies fongiques s'attaquent à la culture du pommier. Afin de lutter contre ces organismes nuisibles dans le but d'éviter des pertes trop importantes, les pomiculteurs ont recours à la lutte chimique. Les vergers de pommiers québécois reçoivent en moyenne de 11 à 15 traitements de pesticides annuellement. Or, tous ces produits ne sont pas sans conséquences pour les organismes non ciblés. Certains affectent grandement les populations de prédateurs et parasites présents qui autrement participeraient à la lutte biologique du verger et diminueraient ainsi l'utilisation subséquente de pesticides. Anystis baccarum (L.), un prédateur acarien peu connu, est un bon exemple. Des études biologiques exploratoires ont permis de déterminer que ce dernier a la capacité de s'attaquer à des ravageurs présents dans les vergers, et ce, tout au long de la saison. Il est cependant presque absent des vergers commerciaux où le recours aux pesticides est fréquent. Des études de toxicité résiduelle dont les résultats ont été publiés dans deux journaux scientifiques ont permis de démontrer la toxicité très élevée de certains pesticides utilisés dans les vergers de pommiers commerciaux sur ce prédateur. Ainsi, leur utilisation entraîne une éradication quasi totale de la population présente. L'extrême toxicité de certains des pesticides testés relativement à la concentration recommandée dans les vergers envers ce prédateur soulève une inquiétude quant à leur toxicité humaine et environnementale. L'évaluation de la toxicité des pesticides, première étape de l'évaluation du risque, effectuée par les fabricants et présentée aux agences de réglementation à des fins d'homologation, est un processus scientifique qui comporte un nombre important de failles. Les protocoles adoptés et les mesures de toxicité utilisées, les hypothèses non vérifiées, le manque de représentativité dans les études écotoxicologiques entre les espèces testées et les régions où sont utilisés les produits, le manque de connaissances scientifiques quant à la validité de l'extrapolation des résultats des tests effectués chez les animaux aux humains, les effets sous-létaux qui, loin d'être négligeables, ne sont pas évalués, etc. démontrent que l'évaluation du risque de ces pesticides ne peut adéquatement rendre compte des dangers de ces produits pour l'humain et pour l'environnement. De plus, l'analyse de l'état des connaissances des agences de réglementation canadienne et américaine permet de constater que des pesticides sont homologués sans que toutes les études exigées soient présentées. On utilise donc des pesticides dans les vergers de pommiers québécois qui sont hautement toxiques pour les insectes et acariens bénéfiques. On nuit ainsi grandement à la biodiversité et à l'équilibre de l'écosystème. Par ailleurs, les agences de réglementation ne détiennent pas toutes les informations quant à la toxicité humaine et environnementale de ces pesticides. De plus, la validité des résultats des études évaluant leur toxicité est très discutable. Bien que la science ait considérablement avancé depuis l'arrivée sur le marché des pesticides, les dispositifs actuels d'évaluation de la toxicité de ces produits demeurent parsemés d'incertitudes. N'est-ce pas un exemple concret où le principe de précaution qui stipule qu'en cas de risque de dommages graves ou irréversibles, l'absence de certitude scientifique absolue ne doit pas servir de prétexte pour remettre à plus tard l'adoption de mesures effectives visant à prévenir la dégradation de l'environnement? En ce sens, notre étude de certains pesticides interroge très sérieusement la rigueur avec laquelle le mandat de protection de la santé publique et environnementale est rempli par les instances gouvernementales concernées. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Anystis baccarum, Pomiculture, Pesticides, Toxicité humaine, Écotoxicité, Évaluation du risque.