Toxicity of insecticides to obliquebanded leafroller, Choristoneura rosaceana, larvae and adults exposed previously to neem seed oil

Abstract

Adult and sixth instar obliquebanded leafroller, Choristoneura rosaceana (Harris), exposed previously as fifth instar larvae to sub‐lethal concentrations of neem, Azadirachta indica A. Juss., seed oil contained in artificial diet were more susceptible to topically applied pyrethroid, carbamate and organophosphate insecticides than C. rosaceana reared on control diets. Increased susceptibility to insecticides did not result from reduced vigour, as measured by reductions in adult or larval weights, but is instead correlated with previously demonstrated reductions in detoxication enzyme activities. The modest increases in susceptibilities, not exceeding ca. 4.5‐fold, for C. rosaceana exposed to neem were achieved with subjects from a susceptible laboratory colony; a larger response could be expected for resistant field populations having elevated detoxication enzyme levels. Neem‐based insecticides could be useful tools for the management of orchard pests that have developed resistance to synthetic neurotoxins. These findings also contribute to a better understanding of the numerous physiological changes that occur in larval Lepidoptera following exposure to neem extracts.

Topical Toxicity of Spinosad and Its Impact on the Enzymatic Activities and Reproduction in the CockroachBlatta orientalis(Dictyoptera: Blattellidae)

“…The GST activities generally take part in converting a reactive lipophilic molecule into a water-soluble, non-reactive conjugate, which may easily be excreted (Yu & Abo-Elghar 2000). The present results revealed an induction in GST activities when females B. orientalis were treated by spinosad, confirming previous reports using various insecticides such as triazine in Spodoptera frugiperda (Yu 2004), azadirachtin in Choristoneura rasaceana (Lowery & Smirle 2000) and boric acid in B. germanica (Habes et al 2006). Sometimes, the GST activities could be not affected by azadirachtin in Choristoneura rasaceana (Smirle et al 1996) and by chlorpyrifos in Chironomus riparus (Callaghan et al 2001).…”

6β-Hydroxygedunin from Azadirachta indica. Its Potentiation Effects with Some Non-azadirachtin Limonoids in Neem against Lepidopteran Larvae

“…Obviously, limonoids can have different primary modes of action depending on the test insect species, and they can exhibit both antifeedant and toxic modes of action (27). Oral administration, topical application, and injection of limonoids have been shown to interfere with growth via secretion of trypsintype proteinases from gut epithelial cells and other digestive and catabolic enzymes (9,28,29). It is, therefore, possible that gedunin-type limonoids act in a similar fashion and damage the insect's digestive tract.…”

Eficiência e efeitos subletais de nim sobre Bonagota salubricola (Meyrick) (Lepidoptera: Tortricidae)

“…A eficiência de produtos à base de nim foi destacada por Góez et al (2003), os quais constataram que, dentre vários extratos vegetais, aqueles oriundos de A. indica estão entre os mais eficientes no controle de diversos lepidópteros-praga. A eficiência de A. indica no controle de tortricídeos foi demonstrada por Lowery & Smirle (2003), os quais verificaram elevada toxicidade de um extrato de sementes de nim a lagartas de Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae). Adicionalmente, constataram que o extrato, quando aplicado topicamente (0,5 µL/larva de sexto instar), em concentrações de 0,002% a 0,032%, ocasionou alterações fisiológicas que tornaram os insetos sobreviventes mais suscetíveis aos inseticidas piretroides, carbamatos e organofosforados comumente utilizados para controle da praga em pomares de macieira.…”