Residual toxicity of three insecticides against the parasitoid, <i>Arrhenophagus albitibiae</i> Girault (Hymenoptera: Encyrtidae), parasitizing <i>Pseudaulacaspis pentagona</i> (Targioni-Tozetti) (Hemiptera: Diaspididae) on tea trees and side effects of clothianidin applied in a tea field

Abstract

We investigated the residual toxicity of three insecticides (methidathion, bifenthrin, and clothianidin) against the parasitoid Arrhenophagus albitibiae Girault (Hymenoptera: Encyrtidae) parasitizing white peach scale Pseudaulacaspis pentagona (Targioni-Tozetti) (Hemiptera: Diaspididae) on tea trees. In addition, we investigated the effect of clothianidin on parasitism by parasitoids (including A. albitibiae) in a tea field. Tea branches were sprayed with the insecticides. Changes in insecticide toxicity and residues on tea branches and leaves were monitored. Methidathion was toxic to A. albitibiae adults for fewer than 10 days after the application, while residues on leaves and branches lasted approximately three weeks. The toxicity of bifenthrin lasted for less than 10 days after application. Bifenthrin residues on leaves were detected fewer than four weeks after application, while residues on branches were present for more than four weeks. Clothianidin was toxic for more than two weeks after application. Its residues on leaves lasted about one week, while residues on branches lasted for more than four weeks. Clothianidin application immediately after the peak of occurrence of the A. albitibiae slightly inhibited parasitism of P. pentagona by A. albitibiae.