Toxicological studies of novel reduced-risk insecticides in obliquebanded leafroller, Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae).

摘要

Historically, broad-spectrum insecticides have been the primary tools to manage insect pests in tree fruits. Use of broad-spectrum insecticides such as organophosphates (OPs) for decades has resulted in the development of OP resistance and cross-resistance to other classes of insecticides in major pests including obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). Additionally, regulatory actions such as Food Quality Protection Act of 1996 (FQPA) have put restrictions on the use of broad-spectrum insecticides leading to OP phase-out. The development of insecticide resistance and implementation of FQPA along with restrictions in international markets have led to the development of new chemicals such as chlorantraniliprole and spinetoram which are more environmentally friendly. With the availability of these products, it was critical for tree fruit growers to incorporate the novel reduced-risk insecticides into IPM programs. However, very little information was available to growers on how to utilize these reduced-risk products in IPM programs in a sustainable manner.;With that in mind, studies were initiated to investigate lethal and sublethal effects, stage-specificity, and residual efficacy of these chemicals using OBLR as a model species. Field populations were tested to establish the baseline susceptibility, and a laboratory population was selected for resistance to assess the risk of resistance evolution and determine possible resistance mechanisms. These investigations revealed that chlorantraniliprole and spinetoram have strong lethal as well as sublethal effects. They were highly effective against OBLR larvae regardless of larval age and have very long residual activity. However, evidence of resistance and cross-resistance in the field as well as development of resistance in response to laboratory selection indicates that the risk of resistance evolution against these chemicals exists. Studies also showed that in the absence of selection populations reverted to being susceptible and that different detoxification systems were involved with each chemical. This latter fact indicates that chlorantraniliprole and spinetoram could be effectively incorporated into resistance management programs through strategies of rotation. Implementation of such strategies at this point would be a proactive approach and would lead to management of OBLR and other major pests of tree fruits on a sustainable basis.