Synergistic interaction between sublethal doses of Bacillus thuringiensis and Campoletis chlorideae in managing Helicoverpa armigera

Abstract

Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important solitary larval endoparasitoid of the tomato fruit borer Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in India. The interaction between Bacillus thuringiensis subspecies kurstaki (Btk) HD-1 and C. chlorideae was studied under laboratory condition to explore their compatibility in managing H. armigera. The results had indicated that the growth and development of H. armigera was affected in a dose-dependent manner upon feeding on sublethal doses of Btk HD-1-treated diets. There were no larval survivors in lethal doses of Btk HD-1 (LC 70 and LC 90 ). The growth and survival of the parasitoid were normal when the host larvae were fed with sublethal doses or subjected to short time exposure to lethal doses of Btk HD-1. However, the parasitoid offsprings developed slowly and pupal as well as adult period, adult weight and adult emergence rate were reduced significantly if the parasitoid was developing inside a severely Bt intoxicated host larvae. There were no evident differences in longevity of parasitoid adults that were fed on honey solution containing different concentrations of Btk HD-1 as compared to adults fed only on honey solution. This indicates no direct adverse effect of Btk HD-1 on C. chlorideae. Further, the gravid female parasitoid did not discriminate Btk HD-1 intoxicated and normal H. armigera larvae for oviposition. The result implies that spore crystal formulation of Btk HD-1 can be effectively used in a synergistic manner along with existing natural or prereleased population of C. chlorideae in organic farming or as components in biointensive IPM module for managing H. armigera.

Effect of Bacillus thuringiensis on Habrobracon hebetor during combined biological control of Plodia interpunctella

“…This study is suggestive of adult parasitoids not being directly affected by Bt toxin. The adult longevity and adult weight were reduced only if the parasitoid offspring developed from severely Bt ‐intoxicated host larvae (Mohan et al ., 2008). A similar result had earlier been reported (Liu et al ., 2005).…”

“…Second, H. hebetor larvae may have fed on Bt ‐contaminated host tissue, thereby killing them. High mortality among parasitoid larvae growing on contaminated host larvae has been previously observed (Raguraman & Singh, 1998; Erb et al ., 2001; Mohan et al ., 2008). Although there was difference in the percentage adult emergence between treatments, none of them appeared to inhibit H. hebetor emergence.…”

The Effect of Plant Quality on Survival of Lymantria Dispar (Lepidoptera: Lymantriidae) Larvae Infected by Bacillus Thuringiensis Berliner Subsp. Kurstaki

“…Significant reductions were found in pupal weight, larval weight, normal pupation and prolonged larval period of Heliothis armigera Hübner (Lepidoptera: Noctuidae) larvae fed on sublethal doses of B. thuringiensis (Mohan et al, 2008). In this study, bacteria intensity was reduced by subtilizing 10-fold less than normal dose for infection.…”

“…Studies on entomopathogenic bacteria focused on finding their efficacy in terms of lethal concentration and killing speed (Deilamy and Abbasipour, 2013), their susceptibility of different stages of larval development to the pathogen (Erb et al, 2001;Gilliland et al, 2002) and the efficacy of sublethal effects on larval development (Mohan et al, 2008). Significant reductions were found in pupal weight, larval weight, normal pupation and prolonged larval period of Heliothis armigera Hübner (Lepidoptera: Noctuidae) larvae fed on sublethal doses of B. thuringiensis (Mohan et al, 2008).…”

Fitness costs of sublethal exposure toBacillus thuringiensisinHelicoverpa armigera: a carryover study on offspring

“…In addition, synergistic interaction between sublethal doses of Btk and Campoletis chlorideae Uchida (Hym. : Ichneumonidae) in managing H. armigera was investigated by Mohan et al (2008). However, as there is no detailed information regarding the sublethal effects of Btk on the biological performance of H. armigera, this work was undertaken to evaluate such effects.…”