Oxidative stress responses to sub-lethal dose of Cry toxin in the larvae of castor semilooper, Achaea janata

Abstract

Development of synthetic insecticides to reduce the level of infestation led to deleterious effects on environment and human health. This lead to the development of ecofriendly pest management alternatives including Bacillus thuringensis (Bt). Bt produce Crystal (Cry), Cytotoxic (Cyt) and Vegetative (Vip) proteins with insecticidal activity against different orders of lepidoptera. Of late, pest resistance against Bt is reported in countries.The reduced toxicity of Bt formulation from degradation by UV light, wash-off by rain, drying, temperature, and soil acidity as well as its chemistry. Further, insects sense pesticides through odorant receptors and move away quickly, there is always a possibility of a population of larvae to get exposed to sub-lethal doses of toxin which might exhibit variable effects and escape mortality and eventually generate resistance. Sub-lethal dose lead to the generation of oxidative stress in the insect and eventually scavenged by anti-oxidant enzymes. These stress responses would enhance our understanding of adaptations for survival and resistance development. The current study is an attempt to monitor the antioxidative responses at the transcriptional level upon sub-lethal exposure of Cry toxin in the larvae of an polyphagous pest castor semilooper, Achaea janata. prevalent in the Indian subcontinent.