Mode of entry of a vaporized pyrethroid knockdown agent into the body of the housefly, Musca domestica (Diptera: Muscidae)

Abstract

We investigated the mode of entry of pyrethroids into the insect body using adult housefly, Musca domestica L., as an insect model. The wings of adult female houseflies were removed, and empenthrin was applied topically to three different sites: the mesothoracic spiracle, the ventral mesothorax, and the dorsal mesothorax. Among these treatments, the application of the compound to the mesothoracic spiracle led to the quickest knockdown of the flies. To determine the importance of the spiracle as a primary entry site for the pyrethroid, knockdown times were compared between houseflies with blocked and non-blocked spiracles, using two bioassays: a vapor action test using technical grade empenthrin, and a mosquito coil test using empenthrin-impregnated coils. In both tests, the times required for 50 % knockdown of spiracle-blocked houseflies were significantly higher than those required for the non-blocked flies. However, the mortality rates of the two groups were nearly identical, suggesting that spiracles play an important role in the knockdown of houseflies. These results also suggest that the rate of pyrethroid uptake through the spiracles was decreased due to the blocking of the mesothoracic spiracle. Therefore, the spiracle may be considered the main entry site for vaporized pyrethroids.

Toxicity of Miana Leaf (Coleus blumei) Extract Against Houseflies (Musca domestica)

“…That method results in poisoning that occurs in the respiratory system and affects the nervous system in houseflies (Wirawan, 2006). This is in accordance with the statement of Sumita et al (2016), where spiracles located on the body surface of insects play an important role as a cause of knockdown in housefly. Vapor extracts enter the spiracles and quickly enter the insect nervous system, then inhibit the action of the acetylcholinesterase enzyme and finally a knockdown occurs.…”

Tying pest insects in knots: the deployment of spider‐venom‐derived knottins as bioinsecticides

“…Deployment of spider knottins as bioinsecticides is not necessarily contingent upon the presence of oral activity. Insects breathe via external openings on their exoskeleton called spiracles, and these openings are the major route for the entry of aerosolized pyrethroids and possibly other chemical insecticides . After breaching the spiracles, these insecticides are thought to enter the hemolymph through the walls of the trachea.…”

Vapor toxicity of five volatile pyrethroids against Aedes aegypti, Aedes albopictus, Culex quinquefasciatus, and Anopheles quadrimaculatus (Diptera: Culicidae)

“…Penetration barriers are directly applicable to traditional mosquito adulticiding, which relies on dispersing fine droplets through the air to impinge upon and penetrate the cuticle of the target. However, volatile pyrethroids diffuse as a gas, allowing passage through the thin, permeable endocuticle of the trachea and potentially avoiding some cuticle barriers. Thus, one might expect greater penetration from volatile pyrethroids than more contact‐active pyrethroids perhaps due to bypassed epicuticle and reduced metabolism due to halogenated sites.…”