Resistance of diamondback moth to insecticides in selected cabbage farms in southern Ghana

Abstract

Resistance of diamondback moth (DBM), Plutella xylostella (L.) to insecticides applied for its control on cabbage was evaluated. DBM populations were tested for susceptibility to three pyrethroids (delatamethrin, lambdacyhalothrin, cypermethrin) and an organophosphate (chlorpyrifos-methyl) insecticide using larvae immersion dose-response technique. Non-specific carboxylesterase activity was used as a measure of DBM resistance. Partial characterization of carboxylesterase by zymogram studies was also undertaken using polyacrylamide gel electrophoresis (PAGE). Susceptibility studies revealed that DBM was resistant to the four insecticides assayed. DBM was least susceptible to chlorpyrifos-methyl, but most susceptible to deltamethrin. Esterase zymogram studies revealed between 2 to 7 bands, each with different characteristics. Higher frequency of the slow-moving esterases associated with high resistance was recorded in Mampong DBM population than the Accra suburbs. This finding confirmed results for carboxylesterase activity. Deltamethrin and cypermethrin demonstrated high negative correlation between fold resistance and carboxylesterase activity for β-isozyme. Chlorpyrifos-methyl, on the other hand showed positive correlation between fold resistance and α-carboxylesterase activity. The high carboxylesterase activities recorded for Mampong DBM, however, did not correlate with results of susceptibility studies. It is suggested that farmers should adopt an integrated approach using the IPM principles coupled with judicious use of biopesticides such as Bacillus thuringiensis.

Esterase activity in homogenates of Helicoverpa armigera (Hubner) (Lepidoptera: noctuidae) exposed to different insecticides and the behavioral effect

“…Bacillus thuringiensis and chlorpyrifos showed higher LC 50 and LC 95 values than those recommended by the manufacturer, as well as increased alpha and beta esterase activity. The high the alpha and beta esterase activity observed in H. armigera population indicates a higher metabolic rate, which may mean some level of resistance, a likely consequence of a long period of exposure to organophosphate, pyrethroids and cry toxin, for example (ODHIAMBO et al, 2010;DAWKAR et al, 2016). These enzymes are able to metabolize the insecticides, due to the high expression of the genes that codify them.…”

Pesticide resistance in Plutella xylostella (Lepidoptera: Plutellidae) populations from Togo and Benin

“…In urban and peri-urban vegetable cultivation areas around Cotonou, cabbage producers apply insecticides, especially pyrethroids and organophosphates, every 3 to 4 days within a 3-month period before harvesting (James et al, 2010), thereby inducing a high selection pressure. The low susceptibility of field populations of P. xylostella with regard to chemical insecticides was observed in Ghana (West Africa) where Odhiambo et al (2010) showed high LC 50 of 386-802 mg/l and 74,617-170,573 mg/l for deltamethrin and chlorpyrifos ethyl, respectively.…”

“…As reported from several tropical countries (Talekar and Shelton, 1993;Baek et al, 2005;Nyambo and Löhr, 2005;Ayalew, 2006;Odhiambo et al, 2010;Santos et al, 2011;Zhou et al, 2011;Legwaila et al, 2014), P. xylostella populations from Togo and Benin also appear to be resistant to a number of insecticides commonly used in different agroecosystems (Goudegnon et al, 2000;Martin et al, 2006;Godonou et al, 2009;Agboyi et al, 2013). As a reaction to this phenomenon, cabbage producers have entered the vicious circle of increasing both insecticide dosage rates and spraying frequencies (Ahouangninou et al, 2012), which can lead to environmental and health hazards (Pimentel et al, 1997;Gallivan et al, 2001).…”

Diversity and Genetic Structuration of Populations of <i>Plutella xylostella</i> (Lepidoptera, Plutellidae), Cabbage Farming Destroyer in Senegal

“…According to Gnago et al [5], caterpillars of the P. xylostella, seem to have developed a certain resistance against the insecticide Kart 500 SP. Odhiambo et al [6] noticed these forms of resistance to insecticides of pyrethrinoïd type and DDT (Dichloro-Diphenyl-Trichloro-ethane) too; these are abusively used at high dose by farmers [2]. The use of these chemical products gives rise to different varieties of resistant insects, which results in the emergence of different haplotypes between populations [7].…”