• VIJESH VARGHESE
• M. GOKULDAS

ABSTRACT: Carboxylesterases are major enzymes involved in the detoxification of insecticides in several insect species. The activity of these catalysts reaches the maximum at optimum temperature and hydrogen ion concentration (pH). The banana rhizome weevil (BRW) Cosmopolites sordidus Germar (Coleoptera: Curculionidae) is one of the most important pests of bananas and plantains. The impacts of temperature and pH on the hydrolysis of both α-naphthyl acetate and β-naphthyl acetate by C. sordidus carboxylesterase and the distribution of these enzymes in different tissues were examined. The ideal conditions of carboxylesterase activity in C. sordidus were a pH of 6.6 - 7.2 and a temperature of 35°C - 45°C. The enzyme activity showed gradual increase to reach an optimum at pH 6.8 after which the activity gradually declined. As to temperature, the enzyme activity showed gradual increase to reach its maximum at 40°C after which the activity gradually declined. Most enzymes have optimum temperature and pH conditions for maximal activities and in this study, the activity of carboxylesterase enzymes in C. sordidus were shown to have an optimum temperature of 40°C and an optimum pH of 6.8. The specific carboxylesterase enzyme activity on α-naphthyl acetate and β- naphthyl acetate is higher in insect gut than fat body and haemolymph and it was that gut was the tissue with richest carboxylesterase enzyme activity. The significance and the role of carboxylesterase activity in detoxification of pesticides are discussed.

Keywords: Cosmopolites sordidus, Carboxylesterase, α-Naphthyl acetate, β-Naphthyl acetate.

"ACTIVITY OF CARBOXYLESTERASE ENZYME IN VARIOUS TISSUES OF COSMOPOLITES SORDIDUS GERMAR (COLEOPTERA: CURCULIONIDAE) UNDER VARIOUS CONDITIONS OF TEMPERATURE AND pH", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.6, Issue 3, page no.192-198, March-2019, Available :http://www.jetir.org/papers/JETIR1903632.pdf

"ACTIVITY OF CARBOXYLESTERASE ENZYME IN VARIOUS TISSUES OF COSMOPOLITES SORDIDUS GERMAR (COLEOPTERA: CURCULIONIDAE) UNDER VARIOUS CONDITIONS OF TEMPERATURE AND pH", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.6, Issue 3, page no. pp192-198, March-2019, Available at : http://www.jetir.org/papers/JETIR1903632.pdf