Inhibition of sex pheromone communications of Trichogramma brassicae (Hymenoptera) by the insecticide chlorpyrifos

Abstract

Biological control agents such as entomophagus insects (e.g., Trichogramma sp.) are important components of integrated pest management (IPM) programs. Because pesticides are also an important component of IPM programs, it is essential to understand how biological control agents are affected by pesticides and how these effects may affect the effectiveness of the biological control agents. Contrary to most insect species that use volatile pheromones for mate location, T. brassicae is one of the few species using a substrate‐borne sex pheromone for mating. In this work we determined the effects of an organophosphorus insecticide, chlorpyrifos, on sex pheromone reception by males and emission by virgin females. The insects used in the pheromone tests were survivors from an acute toxicity test in which individuals were exposed to a dose of chlorpyrifos equivalent to a 20% lethal dose. Males that survived the insecticide exposure spent much less time on the area marked with the female pheromone than control males (mean choice indexes, 0.46 [0.34 SD] vs 0.70 [0.25 SD], p < 0.001). The kinetics of the response of males to marking by control and treated females indicated that chlorpyrifos decreased the emission of sex pheromone by females surviving the insecticide. Therefore, chlorpyrifos inhibited pheromone reception by males and decreased pheromone emission by virgin females. These results are interpreted in the context of sex pheromone regulation by the nervous system of insects and according to the mode of action of chlorpyrifos. Extensions of these results on actual work on sex pheromone, the use of pheromone traps, and the population biology of Trichogramma sp. are discussed.

Impact of Chemical Insecticide Application on Beneficial Insects in Maize

“…This case study investigated the impact of insecticide side effects on some natural enemies of maize pests. These effects depend mainly on the chemical nature of the active ingredients and the dose applied, and can cause lethal and/or sublethal effects [20][21][22][23][24].…”

“…With respect to the genus Trichogramma, there is an extensive bibliography on the effects of insecticide applications, given the importance of this egg parasitoid as a potential biocontrol agent in many countries [20][21][22][23][24][29][30][31][32][33][34][35][36][37]. Several active ingredients have been…”

Sublethal Effects of Four Insecticides Targeting Cholinergic Neurons on Partner and Host Finding in the Parasitic Wasp Nasonia vitripennis

“…This idea is supported by the fact that dimethoate disrupted the pheromone response, while the preference for host odor even turned into avoidance at doses ≥0.21 ng. Interestingly, chlorpyrifos, another organophosphate insecticide, disrupted the male pheromone response in the egg parasitoid T. brassicae (Delpuech, Froment, et al, 1998;Delpuech, Gareau, et al, 1998), while it even increased the response of females to host-associated kairomones in the Drosophila-parasitoids Leptopilina heterotoma and L. boulardi (Delpuech et al, 2005;Rafalimanana et al, 2002). Pheromones in insects are often perceived and processed by specialized components of the olfactory system (pheromone receptor proteins, pheromone-binding proteins, macroglomerular complex in the antennal lobe) that differ from those for general, foodassociated odorants (Renou, 2014).…”

“…Consistent with this hypothesis, insecticides targeting nAChRs have been shown to interfere with chemical orientation of parasitic wasps. Males of the egg parasitoid Trichogramma brassicae exposed to the organophosphate chlorpyriphos were less arrested by the female sex pheromone (Delpuech, Froment, et al, 1998;Delpuech, Gareau, et al, 1998). Females of the ichneumonid wasp Microplitis croceipes feeding on extrafloral nectar contaminated with imidacloprid were impaired in responding to herbivoreinduced volatiles released from infested host plants (Stapel et al, 2000).…”

Comparative Toxicity of Insecticides against Trichogramma chilonis (Hymenoptera; Trichogrammatidae) under Laboratory Conditions

“…The natural population of T. chilonis contributed for the control of pests' population. Therefore, the effects of environmental pollutions on this specie by the insecticides also showed significant risk for the protection of biodiversity (Delpuech et al, 1998;Shehzad et al, 2021). T. chilonis are mostly exposed in the foraging process to insecticides in the lepidopterous pests of IPM program.…”