Efficacy, persistence, ground deposition, and human exposure of polymer-encapsulated lindane and chlorpyrifos used for control of the southern pine beetle

Des applications de lindane et de chlorpyrifos ont été étudiées pour déterminer si l'encapsulation dans un polymère augmente la répression du dendroctone méridional du pin (Dendroctonusfrontalis), diminue l'étendue des retombées, augmente la durée d'adhésion à l'écorce ou réduit les contacts humains, en comparaison avec des applications de concentrés émulsifiés.L'encapsulation n'augmente pas l'efficacité et ne réduit pas les retombées des insecticides par rapport aux applications émulsifiées normales. L'encapsulation du chlorpyrifos augmente la persistance résiduelle mais n'affecte pas la persistance du lindane. Le risque de contact humain avec l'écorce encore humidifiée par le chlorpyrifos encapsulé est 2,2 fois plus élevé tandis que le risque de contact du lindane n'est pas influencé par l'encapsulation. Cependant, une fois l'insecticide séché, les applications encapsulées réduisent le risque de contact humain de 90% pour le lindane et de 83% pour le chlorpyrifos.Formulations of lindane and chlorpyrifos were evaluated to determine if polymer encapsulation extended the duration of southern pine beetle (Dendroctonusfrontalis) control, reduced ground deposition, increased persistence on bark or reduced potential human exposure relative to emulsifiable concentrate formulations. Encapsulation did not extend efficacy or reduce ground deposition of either insecticide when compared with the standard emulsifiable formulations. Encapsulation extended residue persistence of chlorpyrifos on bark, but not of lindane. The potential risk of human exposure to bark which was still wet with chlorpyrifos was increased 2.2 times by encapsulation, whereas, similar exposure to lindane was unaffected by encapsulation. After the insecticides had dried on the bark, the encapsulated formulations reduced risk to lindane by approximately 90% and by 83 % for chlorpyrifos

Tree diversity reduces herbivory by forest insects

Biodiversity loss from plant communities is often acknowledged to affect primary production but little is known about effects on herbivores. We conducted a meta-analysis of a worldwide data set of 119 studies to compare herbivory in single-species and mixed forests. This showed a significant reduction of herbivory in more diverse forests but this varied with the host specificity of insects. In diverse forests, herbivory by oligophagous species was virtually always reduced, whereas the response of polyphagous species was variable. Further analyses revealed that the composition of tree mixtures may be more important than species richness per se because diversity effects on herbivory were greater when mixed forests comprised taxonomically more distant tree species, and when the proportion of non-host trees was greater than that of host trees. These findings provide new support for the role of biodiversity in ecosystem functioning across trophic level