Effect of pesticide on mortality and parasitizing ability of parasitoid Aphytis species of san jose scale (Quadraspidiotus perniciosus)

Abstract

An experiment was conducted during July-November 1991 to study the effect of 10 pesticides on mortality and parasi tizingability of a parasitoid Aphytisi sp of san jose scale [Quadraspidiotus perniciosus (Comstock)]. Insecticides, viz dimethoate,phosphamidon, monocrotophos each @ 0.05%, and fenvalerate @ 0.005% were found highly toxic to the adults of Aphytis sp.Fungicides, viz. captan (Captal 0.1%), mancozeb (IndofiI 0.3%). captafol (Foltof 0.2%), carbendazim (Bavistin 0.3%), copperoxychloride (Fytolan 0,2%) and bitertanol (Baycor 0.1 %), caused 14.0-30.0% mortality to adult parasitoid after 24 hr ofconstant exposure. A day after spraying, mortality was 86.0-94.0% in insecticidal treatments compared with 6.0-15.0% infungicidal treatments. However, parasitoids could parasitize 26.0-40.0% hosts in fungicidal treatments compared with 1.6-7.0%in insecticidal treatments. Even 7 days after treatments, high mortality and low parasitism were obtained in insectioidaltreatment compared with moderate parasitism in fungicidal treatments. The parasitism was almost uniform 3 weeks aftertreatment, being 67-0.89.0% in insecticidal and 76.0-84.0% in fungicidal treatments.