Resistance of Brazilian diamondback moth populations to insecticides

Abstract

Plutella xylostella is a recurring pest on cruciferous crops around the world. In Brazil, it typically requires large number of insecticide sprays, which may lead to fast evolution of resistance. The aim of this study was to assess the susceptibility of Brazilian diamondback moth populations to the insecticides abamectin, deltamethrin, and spinosad. Leaf dip bioassays were used to determine mortality data obtained after 48 h of exposure to insecticides and subjected to Probit analysis. The population from Bonito, state of Pernambuco, Brazil, had the highest toxicity ratio (20.2 -fold) to abamectin compared to the reference population. The LC 50 values for deltamethrin ranged from 85.2 to 360.1 mg L -1 , demonstrating a high survival of populations in relation to this insecticide field dose rate (7.5 mg L -1). The toxicity ratios of the estimated LC 50 s, however, were very low (varying from 2.2 -to 4.2 -fold). Most populations exhibited toxicity ratios for spinosad, ranging from 2.3 -to 5.1 -fold, while both the LC 50 and LC 95 values reflected a high susceptibility to the spinosad field dosage (120 mg L -1).Only the Bonito -PE population resisted to abamectin, while all P. xylostella populations were resistant to deltamethrin, but particularly susceptible to spinosad because of the absence of selection pressure with it in these areas.

Tri-Trophic Insecticidal Effects of African Plants against Cabbage Pests

“…Plutella xylostella is reported to be the first crop pest to have developed resistance against dichlorodiphenyltrichloroethane (DDT) and the first to develop resistance to Bacillus thuringiensis ( Bt ) insecticides [33,37,38] thus, any botanical that is able to offer a significant control will be considered valuable. In Brazil [39], reported that it is normal for farmers to apply between 15-20 insecticide sprays within a cropping season with at least three applications in a week, without success, in an effort to reduce yield losses caused by P. xylostella . The ability of the botanicals to significantly manage the populations of P. xylostella , as well as B. brassicae , in this study is an indication of their potential usefulness in integrated pest management (IPM) of cabbage, especially for resource-limited farmers.…”

Fitness costs and life table parameters of highly insecticide‐resistant strains of Plutella xylostella (L.) (Lepidoptera: Plutellidae) at different temperatures

“…DBM has developed resistance against many different chemical classes of insecticides, such as organophosphates, pyrethroids, benzoylureas, abamectin, indoxacarb and B. thuringiensis ( Bt ) . However, most recently DBM has evolved high levels of resistance against diamide insecticides such as chlorantraniliprole and flubendiamide owing to the extensive use of this new class in different geographies .…”

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

“…The greater effectiveness of spinosad can be explained by its mode of action, targeting different sites such as nicotinic acetylcholine receptor and GABA receptor (Thompson et al, 2000). Our results suggest the absence of cross resistance with pyrethroid and organophosphate as observed by Oliveira et al (2011) for P. xylostella populations, while Sparks et al (1995) showed that spinosad was effective against a Heliothis virescens population resistant to cypermethrin (pyrethroid) and profenofos (organophosphate). Legwaila et al (2014) also demonstrated that spinosad can achieve effective control of resistant P. xylostella population in Botswana.…”