Effects of some insecticides on biological characteristics of egg parasitoid Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) in pre- imaginal stages

The egg parasitoid Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) is an important natural enemy of insect pests in various agricultural systems. In this study, the effects of three different insecticides (Lambda-cyhalothrin, Chlorantraniliprole, and Indoxacarb) at five different doses (field rate (FR), FR, FR/2, FR/4, FR/8, FR/16) and three different pre-adult stages (larva-2 days old, prepupa-4 days old, and pupa-6 days old) on the emergence rate (%) and biological characteristics of T. evanescens were in vestigated. Statistically significant effects on the emergence rate (%) of the parasitoid were observed for all insecticides used in the study, as well as for their application doses and the pre-adult biological stage sex posed to the insecticide doses. Lambda-cyhalothrin had the most adverse effect on T. evanescens, followed by Chlorantraniliprole and Indoxacarb. The FR/16 dose of Lambda-cyhalothrin insecticide negatively affected the parasitoid's emergence rate, and the larval stage (2 days old) of the parasitoid was the most sensitive. Similarly, Chlorantraniliprole was found to have the highest negative effect on the parasitoid's emergence rate at the FR dose, with the larval stage (2 days old) being the most negatively affected biological stage. Indoxacarb had the highest negative effects on the parasitoid's emergence rate at the FR and FR/16 doses, with the larval stage being the most negatively affected biological stage by this insecticide. Inaddition, the side effects of these insecticides and tested doses on various biological characteristics of T. evanescens, such as intrinsicrate of increase (r), finite increase rate (λ), net reproductive rate (R0), mean fecundity (F) ratio, life span, and oviposition periods, were also in vestigated using a life table approach under laboratory conditions (26 ± 1°C temperature, 65 ± 5% relative humidity, and 16:8 L:D photoperiod).