Resistance to Avermectins: Extent, Mechanisms, and Management Implications

Abstract

The avermectins represent a group of natural compounds with potent pesticidal activities. Because of their novel mode of action, they represent an important resource for pest control and resistance management. In the Colorado potato beetle, the house fly, and the two-spotted spider mite, resistance to abamectin is usually autosomal, recessive, and polygenic. Although these aspects are beneficial in resistance management, the fact that resistance could be readily selected for suggests that abamectin needs to be used in moderation. Furthermore, several major resistance mechanisms (e.g. excretion, oxidative metabolism, penetration) and minor factors (e.g. altered target site, conjugation, hydrolysis/sequestration) have been implicated in abamectin resistance. Thus, the question is not whether resistance to abamectin will occur but is simply when and how it will occur. To address this problem, we have gathered information on the genetics, biochemical mechanisms, effectiveness of synergists, and cross-resistances to other insecticides from three abamectin-resistant insects. Judicious implementation of this information may prove useful in the resistance management of this natural pesticide.

Insecticide Resistance and Vector Control

“…The initial mechanisms that conferred resistance to insect growth regulators were oxidase-based (44). Resistance to ivermectins has resulted from a number of factors, including oxidase, conjugation, and altered target-site mechanisms (45). Vectors have not yet demonstrated resistance to these compounds in the field.…”

Biological efficacy of some biorational and conventional insecticides in the control of different stages of the Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae)

“…It is a mixture of avermectins, containing 80% avermectin B1a and 20% avermectin B1b, and Fitoverm, the product containing the active ingredient avermectin C. Mectin and Fitoverm are natural fermentative products of the soil microorganism Streptomyces avermitilis. Its novel chemistry, unique mechanism of toxicity, and broad spectrum of insecticidal activity make abamectin a suitable choice for this purpose (Clark et al 1995). Also, Match is an insect growth regulator (IGR) that has the active ingredient lufenuron with proven wide activity against many pests including CPB and that showed satisfactory residual action, good leaf protection and high yields (Igrc et al 1999).…”

Identification of a Drosophila melanogaster Glutamate-gated Chloride Channel Sensitive to the Antiparasitic Agent Avermectin

“…The activity of the avermectins on the C. elegans GluCl channels shows a good correlation with their in vivo activity, suggesting that the GluCl channels are the targets for avermectin action (11). After many years of use in the field, there remains little resistance to avermectin in the insect populations (14). The combination of a good therapeutic index and low resistance strongly suggests that the GluCl channels remain good targets for insecticide development.…”