Insect defence: its impact on microbial control of insect pests

Insects are the earliest and most diverse taxon of animals accounting for more species than all other animals put together because of their high reproductive potential and varied niche. Though cellular reactions like phagocytosis, nodulation and encapsulation and humoral reaction through secretion of antibacterial proteins are known for fungus and bacterial invaders, little is known about insect defence against insect virus infection. This review provides a brief outline of the current state of knowledge on the various aspects of insect defence mechanisms through their innate, i.e. non-specific reactions, and how the various microbial control agents, viz. entomopathogenic fungi, bacteria, viruses and nematodes try to overcome the insect host defence. The need for basic studies on molecular characterization of major lepidopteran insect pests along with their associated pathogenic microbes has been stressed for better understanding and disarming of insect defence system for further exploitation of insect pathogens for microbial control of insect pests.