Involvement of metabolic and insensitive acetylcholinesterase mechanisms in insecticide resistance of rice insect pests and predatory populations from Batalagoda, Sri Lanka

Abstract

Biochemical assays were carried out within one week of storage to determine the activity levels of major enzyme groups (i.e carboxylesterases, glutathione S-transferases and monooxygenases), which are involved in insecticide metabolism. Native polyacrylamide gels were run with crude homogenates to resolve carboxylesterase isozymes. Sensitivity of the organophosphate and carbamate target site acetylcholineesterase was tested by inhibiting the enzyme with propoxur.N. lugens, S. furcifera and N. virescens showed high insecticide resistance, especially to organophosphates and pyrethroids due to higher activity levels of metabolic enzymes. All the species were susceptible to malathion mainly because of the absence of malathion carboxylesterase mechanism. Resistance to permethrin in the populations of N. lugens, C. lividipennis, M. discolour, O. indica and Tetragnatha sp. may be due to their higher mono-oxygenase activities. Presence of insensitive acetylcholinesterases could be detected among the populations of N.lugens, C. spectra, C. lividipennis and Tetragnatha sp. It appears that multiple resistance mechanisms are present in the populations tested. Higher susceptibility levels of L. oratorius and C. spectra could be attributed to the absence of resistance mechanisms in these two species.

Taxonomy, Bio-Ecology and Insecticide Resistance of Anopheline Vectors of Malaria in Sri Lanka

“…Preservation of high resistance to DDT has been detected not only in malaria vectors but also in other Sri Lankan insect pest populations, such as the populations of dengue vectors Aedes aegypti and Ae. albopictus [45], Japanese encephalitis vectors Culex tritaeniorhynchus and Cx gelidus [46], bed bug Cimex hemipterus [47], sand fly Phlebotomus argentipes [48], cattle tick Rhipicephalus microplus [49] and a range of agricultural insect pests [50]. It has been suggested that underlying mechanisms, especially the enhanced GST-mediated metabolism, initially selected by exposure to DDT, have been subsequently selected by exposure to organophosphates and pyrethroids [42,51,52].…”

Assessing the Single and Combined Toxicity of Chlorantraniliprole and Bacillus thuringiensis (GO33A) against Four Selected Strains of Plutella xylostella (Lepidoptera: Plutellidae), and a Gene Expression Analysis

“…The common mechanisms of metabolic resistance to insecticides include enhanced carboxyl-esterase (CarE), glutathione S -transferases (GST), and cytochrome P450 monooxygenase (MFO) activity [ 13 , 14 , 15 ]. The insensitivity of the target site to organophosphates and pyrethroids is related to the activity of acetylcholinesterase (AChE) [ 16 ]. The correlations between detoxifying enzymes and insecticide resistance have been reported extensively [ 4 ], including the overexpression of enzymatic detoxification involved in resistance in P. xylostella [ 9 ].…”