Imidacloprid increases egg production in Amblyseius victoriensis (Acari: Phytoseiidae)

Abstract

The chloronicotinyl insecticide, imidacloprid, recommended for aphid control in Australian stone fruit orchards, was examined for its impact on survival and egg production in Amblyseius victoriensis Womersley. Imidacloprid at the field rate (0.0053% a.i.) was non-toxic, but repellent to A. victoriensis in laboratory bioassays. Females treated with imidacloprid showed increased egg production, producing 1.9-2.0 eggs per day compared with 1.3-1.6 eggs per day for the untreated individuals. A population of A. victoriensis in an apricot orchard was significantly reduced for 4 weeks following the application of imidacloprid. However, the population recovered after 5-0 weeks and was significantly larger (more than twice) than that in the untreated section of the orchard during weeks 9-12. The imidacloprid-mediated enhancement of the fecundity and population development of A. victoriensis is discussed with respect to integration in existing biological control programmes in the Australian stone fruit.