Insecticide Resistance Research Paper

Diversity of endosymbionts imparting insecticide resistance in leafhopper Amrasca biguttula biguttula (Ishida) through 16s rRNA gene sequencing
G. Sivakumar, Abraham Verghese, Chandish R. Ballal and R. Rangeshwaran
National Bureau of Agricultural Insect Resources, Bengaluru- 560 024, Karnataka, India

Amrasca biguttula biguttula (Ishida) (Hemiptera: Cicadellidae) is one of the serious pest of cotton, okra, sunflower, etc. causing substantial yield loss. Farmers generally use different pesticides 10 to 15 rounds during the crop season against leafhopper. The literature suggests that the leafhopper has developed resistance to the many insecticides recommended, viz., neonicotinoids, metasystox, diamethoate, phosphamidon, imidacloprid and acetamiprid.

The field observations followed by toxicity studies against different insecticides suggest that pest has developed resistance against many insecticides. Recent line of work at global level suggest that gut microbes play an important role that manipulate many physiological functions of the insects, including host-insect morphogenesis, food digestion, nutrition, antifungal toxin production, pheromone production, regulation of pH, synthesis of vitamins, temperature tolerance, resistance against parasitoid development and detoxification of noxious compounds. Our study was pointed towards quantification of microbial diversity present in the alimentary canals and their possible role in insecticide degradation. As evidence by the above role played by microflora in insecticide resistance, present work was carried out to characterize the diversity of culturable microflora and determine their role as endosymbionts in leafhopper A. biguttula biguttula in pesticide degradation, thus imparting insecticide resistance. Identifying the interactions between the insects and their gut bacteria may provide the way for novel approaches for insect control. No attempts have been

The farmers of Dharwad (Karnataka) use acepahte and imidacloprid for control of leafhoppers and this present study also proved the occurrence of high number of bacterial diversity from Dharward population, which indicates that these bacteria were associated with imparting resistance to the insects. Based on the available literature and occurrence across the locations, the two most commonly recorded bacteria, Enterobacter cloacae and Bacillus pumilus were taken to further studies for their role in insecticide resistance, thereby establishing their role as endosymbionts. Maximum growth of Enterobacter cloacae and Bacillus pumilus was recorded when these organisms were observed growing in media amended with acephate and imidacloprid in minimal broth media. Liquid chromatography–mass spectrometry (LCMS) analysis indicated the ability of E. cloacae and B. pumilus recorded from insecticide resistant population of A. biguttula biguttula degraded acephate (183.78) into methamidophos (143.04). The occurrence of common gut bacterial genera Enterococcus, Serratia, Enterobacter, Staphylococcus, Paenibacillus, Pantoea and Bacillus has been reported in many insects on various crops and their role in the host fitness attributes including insecticide resistance was reported by various people. The