Evaluation of metabolic detoxifying enzyme activities and insecticide resistance in Frankliniella occidentalis

Abstract

The western flower thrips Frankliniella occidentalis (Pergande) is a very significant pest of a number of different agricultural crops in the south-east of Spain. The importance of thrips as a pest is not due mainly to the direct damage inflicted on the plant, but to the loss in commercial value which occurs as a consequence of the development of dark spots caused by the tomato spotted wilt virus (TSWV) which they transmit. The economic threshold is therefore almost zero, which enhances the problems of resistance management. The present work is part of a global project that attempts to evaluate the status of insecticide resistance in field populations of thrips obtained from several agricultural crops. We have studied, in either individual or pooled insects, some enzyme systems classically related to detoxification of insecticides: esterase and glutathione-S-transferase (GST). The activity of these enzymes from laboratory populations selected with various classes of insecticides has also been measured using several appropriate substrates. An increase in GST mean activity was found in two field-collected strains. Differences in frequency distributions of esterase and GST activities were found for both field-collected strains and for a laboratory strain selected with acrinathrin. These activities were compared with those of a wild-type reference strain.

Insecticide resistance in field populations of Asian citrus psyllid in Florida

“…Insecticide resistance levels have been positively correlated with levels of detoxifying enzymes in several insect pests. In such cases, detoxifying enzymes have been explained as a mechanism of resistance 20, 27, 28. Although resistant populations of field‐collected adults and nymphs displayed significantly higher levels of detoxifying enzymes, detoxifying enzymes may not be the only mechanism of resistance in this case.…”

Relationship between esterase activity and acrinathrin and methiocarb resistance in field populations of western flower thrips, Frankliniella occidentalis

“…This resistance could be caused by quantitative or qualitative changes in the specific isozymes hydrolysing or sequestering the insecticides 6. In a previous study,28 higher esterase activities were found in resistant populations of F. occidentalis . For the present study, the mean esterase levels towards α‐NA (substrate that is cleaved in insect preparations mainly by carboxylesterases and AChEs)29 and p ‐NPA (considered to be a broad reporter of esterase activity)30 were higher in the resistant strains than in the reference one, in accordance with previous results 28.…”

“…In a previous study,28 higher esterase activities were found in resistant populations of F. occidentalis . For the present study, the mean esterase levels towards α‐NA (substrate that is cleaved in insect preparations mainly by carboxylesterases and AChEs)29 and p ‐NPA (considered to be a broad reporter of esterase activity)30 were higher in the resistant strains than in the reference one, in accordance with previous results 28. The studies carried out by Jensen11, 12 also showed increased total esterase activities to α‐NA or β‐NA when resistant strains were assayed, compared with a susceptible population.…”

Seasonal incidence and enzyme-based susceptibility to synthetic insecticides in two upcoming sucking insect pests of tea

“…Such a failure often occurs due to a change in the susceptibility levels of the pest species to synthetic insecticides. Susceptibility degree changes due to metabolic detoxification of the insecticides through higher activity of some detoxifying enzymes under the stress of different management practices (Jensen 1998(Jensen , 2000Komagata et al 2010;Maymo et al 2002;Wu et al 2011). Generally three principal enzymesgeneral esterases (GEs), glutathione-s-transferases (GSTs) and cytochrome P450 mediated monooxygenases (CYPs) -are involved in the process of metabolic detoxification of insecticides.…”