Carboxyl esterase enzyme- biochemical armour in mediating host defence mechanism of tea mosquito bug (Helopeltis antonii Signoret Miridae: Hemiptera)
Nimisha T, Deepthy KB, Madhu Subramanian, Mani Chellappan and Smitha MS
Tea mosquito bug (TMB),Helopeltis antonii Signoret Miridae: Hemiptera) is the major pest of cashew. The present study was conducted in 2018 at College of Horticulture, Department of Agricultural Entomology, Kerala Agricultural University. Biochemical responses of TMB to different cashew varieties belonging to both less susceptible and highly susceptible groups were analyzed in this experiment. The insect biochemical parameters such as total protein and detoxification enzyme activity (carboxyl esterase) of TMB, infested on selected cashew varieties were analyzed before release (0 h) as well as during different time intervals of feeding. The SDS PAGE profiling of total TMB protein at various time intervals revealed the occurrence of different pattern with notable variation in the appearance of protein bands. Comparative studies on detoxification enzyme levels of TMB revealed that there was a rapid increase in the activity of carboxylesterase in bug released on less susceptible varieties Raghav (258.117 µmol/min/mg protein) and Damodar (208.916 µmol/min/mg protein) when compared to the bugs released on highly susceptible varieties such as Madakkathara-1 and Anagha. These findings imply that exposure of insect towards different levels of secondary metabolites and defense enzymes of host plant will result in variation in activity of detoxification enzyme carboxyl esterase and expression of total insect protein. Results of the study will help to open up new avenues in tea mosquito bug management.