THE EFFECT OF INSECTICIDAL RESISTANCE OF DIAMONDBACK MOTH (Plutella Xylostella) AS A

Abstract

Diadegma semiclausum Hellén (Hymenoptera: Ichneumonidae) is a larval endoparasitoid of Plutella xylostella (L.) (Lepidoptera: Plutellidae), a major pest of crucifer crops. The aim of this study was to evaluate the effect of insecticidal tolerance status of this host on this parasitoid. Host larvae from Waite susceptible (WS), emamectin benzoate selected (EBS) and Bacillus thuringiensis kurstaki selected (BtKS) strains were used in this study. The tolerance in both the EBS and BtKS strains is associated with an inducible tolerance mechanism. Since developmental penalties may be associated with inducible tolerance in some insects, we measured developmental parameters of the host reared on free toxin cabbage. We measured the survival, developmental time, sex ratio and head capsule width of D. semiclausum reared on different host larvae without toxin. The insecticidal tolerance status of the EBS had no effect on any of the measured parameters. However, for the BtKS without toxin the developmental time of the Diadegma males was greater than the WS, but the head width for both sexes was not affected Therefore, this study shows the effect host status associated with BtK, compared to emamectin benzoate toxin, on developmental time and head capsule width on D. semiclausum