Effects of selected pesticides on calico scale populations and their natural enemies in urban honeylocust trees

Outbreaks of calico scale populations in Indianapolis have resulted in increased early season use of pyrethroid and neonicotinoid insecticides in central Indiana. Research was conducted to determine the efficacy of these pesticides against ovipositing and settled calico scales in comparison to more selective insecticides including insect growth regulators and ryanidine inhibitors. Data were also collected on the parasitoid and predator communities on treated and control trees over the course of a season. Imidacloprid and pyriproxifen had little effect on the mortality of ovipositing females when compared with the untreated control trees. Bifenthrin, dinotefuran, chlorantraniliprole and cyantraniliprol all were capable of reducing the population of ovipositing females. The relative contributions of natural enemies and pesticides to overall mortality were also evaluated.