Field Evaluation of Insecticides and Application Timing on Natural Enemies of Selected Armored and Soft Scales

This study was conducted on trees that were naturally infested with either the soft scale, calico scale Eulecanium cerasorum (Cockerell) or armored scales, striped pine scale Toumeyella pini (King) and pine needle scale Chionaspis pinifoliae (Fitch). Insecticides were applied to target the most susceptible life stages of each scale insect. We found that patterns of the seasonal abundance of natural enemies were synchronized with the life history of each scale insect and took the shape of a rising and falling wave. Overall, impacts of insecticides on parasitoids and predators were influenced by the timing of their applications in relation to when natural enemy abundance began to rise at the cusp of their wave of abundance. Application one month prior to this cusp did not reduce seasonal totals of natural enemy abundance, regardless of insecticide selectivity or residual toxicity. In contrast, when applications were made at the cusp of the natural enemy wave, foliar applications of bifenthrin had greater adverse side effects on natural enemy populations compared to foliar applications of pyriproxifen, spirotetramat, spiromesifin, and chlorantraniliprole or a soil application of dinotefuran. We present evidence to suggest that restricting applications during the cusp of the natural enemy activity wave can result in a better integration of chemical and biological control.Graphical abstractWhen applied one month before detectible natural enemy activity, insecticides did not reduce...
Source: Biological Control - Category: Biology Source Type: research