Role of Gut Bacteria Associated with the Chlorpyrifos Resistant Tobacco Leaf Eating Caterpillar Spodoptera litura on the Efficacy of Entomopathogenic Fungi <I>Beauveria bassiana</I> and <I>Poecilomyces</I> Sp.

Abstract

Experiments were conducted to study the role of gut bacteria with insecticide-resistant, insecticide-susceptible and field-caught populations of the lepidopteran insect pest on tobacco, Spodoptera litura - Leaf Eating Caterpillar (LEC). The gut bacteria present in the larvae of LEC was studied in their developmental stages and were found to be significantly different. Results of the gut bacteria of LEC showed that the bacterial population from the chlorpyrifos-resistant larval gut was more varied with Pseudomonas sp., Acinetobacter sp., Serratia sp. and Micrococcus. The susceptible larvae of LEC were harboring Acinetobacter sp. and Serratia sp. and the field-caught population recorded Serratia and Pseudomonas sp. Siderophore producing Pseudomonas sp. showed antagonistic activity towards entomopathogenic fungi, Beaveria bassiana and Paecilomyces sp. whereas the chitinase producing bacteria promoted larval growth and development. The chitin produced by gut bacteria appears to contribute for host nutrition. Study reveals that the bacteria associated with the gut of S. litura is of present day interest to formulate a strategy for pest management programme in tobacco cultivation.