Integrating pesticides and biocontrol of mites in agricultural systems

Abstract

Integration of a biocontrol agent into most agricultural systems will not be successful unless the natural enemy can survive the pesticides used in that crop system. Knowledge of pesticide selectivity to beneficial arthropods is important to their utility in IPM programs. Phytoseiid mites are effective as biocontrol agents in California's fruit crop systems. Galendromus occidentalis and Phytoseiulus persimilis are among the most important the first species is native to the western US, the latter has become established in coastal California. Our previous research has shown that pyrethroids, in particular, affect the abundance of G. occidentalis in almond through both contact and residual activity. Harmful residues existed for over a year on bark, and for 5 months on treated leaves. Several new acaricides have been registered for use in the US since 2000. Abamectin, although registered for many sites prior to these other chemicals, has enjoyed dramatically increased use as replacement for the older products. Understanding the acute and side effects of these new products is important to their successful integration into conservation and augmentation programs. Our recent research was devoted to characterizing the direct and residual effects of a number of new acaricides on survival, fecundity and fertility of G. occidentalis and P. persimilis. Total effect on adult female reproductive potential was calculated and categories for persistence were assigned following IOBC guidelines. Of these acaricides, etoxizole and fenpyroximate had the greatest total effects on both species. Abamectin had the least total effect on G. occidentalis, and acequinocyl had the least total effect on P. persimilis.