Pyrethroid Resistance and Mechanisms of Resistance in Field Strains of <I>Helicoverpa armigera</I> (Lepidoptera: Noctuidae)

Abstract

Pyrethroid resistance was found in 54 field strains of Helicoverpa armigera collected between 1995 and 1999 from 23 districts in seven states of India. LD50 values of the field strains ranged from 0.06 to 72.2 microg/larva with slopes of 0.5-3.1. Resistance was highest in regions where pyrethroid use was frequent (four to eight applications per season). Resistance to deltamethrin was exceptionally high with resistance ratios of 13,570 and 27,160 in two strains collected during February 1998 in central India. Resistance to cypermethrin, fenvalerate and cyhalothrin also was high with resistance ratios of >1,000 in four strains collected from central and southern India. Resistance ratios were below 100 in >50% of the strains tested. Pyrethroid resistance was high in strains collected from the districts in Andhra Pradesh where a majority of the cotton farmer suicide cases in India were reported. Resistance to pyrethroids appeared to have increased over 1995-1998 in most of the areas surveyed. Studies carried out through estimation of detoxification enzyme activity and synergists indicated that enhanced cytochrome p450 and esterase activities were probably important mechanisms for pyrethroid resistance in field strains. Pyrethroid nerve insensitivity also was found to be a major mechanism in some parts of the country where the use of pyrethroids was high. The information presented illustrates the importance of proper insect management programs to avoid the consequences associated with improper insecticide use.

Mitochondrial DNA COI characterization of Helicoverpa armigera (Lepidoptera: Noctuidae) from Paraguay and Uruguay

“…H armigera has a history of rapidly evolving resistance to insecticides such as pyrethroids in India (Kranthi et al, 2001), China (Yang et al, 2004), Africa (Martin et al, 2002), and Australia (Gunning et al, 1991). The Brazilian H. armigera is suspected to have originated from Asia and Europe, although African and/or Australian origins cannot be ruled out, due to the limited availability of DNA sequence data from these two continents (Leite et al, 2014).…”

Esterase-based metabolic resistance to insecticides in heliothine and spodopteran pests

“…The association is particularly strong in data for populations from Australia, [39][40][41][42] south and southeast Asia [43][44][45][46][47][48][49][50][51] and central Africa 52,53) and is also significant in Chinese populations, 46,54,55) although it has not been found in west African populations. [56][57][58] Whether this geographic variation in the strength of the associations reflects genetic differences among populations or methodological differences among investigators is moot, although some effect of genetic differences seems likely.…”

Interaction ofBacillus thuringiensisToxins with Larval Midgut Binding Sites ofHelicoverpa armigera(Lepidoptera: Noctuidae)

“…Larvae cause important economical losses to fiber and vegetable crops and have proven to be difficult to control by conventional means, in part because many pest populations have already evolved resistance to chemical insecticides (20,21,27). A rather recent alternative has been the introduction of cotton expressing a Bacillus thuringiensis insecticidal protein (Bt-cotton).…”