Effect of chitosan on adult longevity when fed to Musca domestica L., Tabanus nigrovittaus Macquart, and Phormia regina (Meigen) adults and its consumption in adult Musca domestica L.

Authors: STOFFOLANO, JOHN - University Of Massachusetts, Amherst; WONG, RAYMON - University Of Massachusetts, Amherst; LO, TIM - University Of Massachusetts, Amherst; FORD, BAYLEE - University Of Massachusetts, Amherst; Geden, Christopher - Chris

Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/6/2020
Publication Date: 7/13/2020
Publication URL: https://handle.nal.usda.gov/10113/7071240
Citation: Stoffolano, J.G., Wong, R., Lo, T., Ford, B., Geden, C.J. 2020. Effect of chitosan on adult longevity when fed to Musca domestica L., Tabanus nigrovittaus Macquart, and Phormia regina (Meigen) adults and its consumption in adult Musca domestica L.. Pest Management Science. https://doi.org/10.1002/ps.5996.
DOI: https://doi.org/10.1002/ps.5996

Interpretive Summary: House flies, horse flies and blow flies are important pests of humans and their associated animals. These flies are difficult to kill because they are highly mobile, and their large body size makes them less susceptible to insecticides than smaller-bodied species. In this paper, scientists at the University of Massachusetts and USDA-ARS-CMAVE (Gainesville, FL) examined the insecticidal properties of the potential control agent chitosan. Chitosan is a polysaccharide derived from chitin that is typically produced from crustacean shells. It is easily made, commercially produced, non-toxic to mammals, biodegradable, and used in a range of agricultural applications. It is also known to toxic to some insects when it is ingested. In this study chitosan was fed to adult house flies (Musca domestica), horse flies (Tabanus nigrovittatus), and blow flies (Phormia regina). Chitosan was toxic to all three flies, although it took several days to kill them. The mode of action appears to be due to a disruption of the microorganisms that live in the gut of the fly.

Technical Abstract: BACKGROUND: The literature mentions that more research needs to be done on using chitosan as an environmentally friendly bioinsecticide, especially against dipterans. Thus, we examined the effect of chitosan when fed to adult Musca domestica, Tabanus nigrovittatus and Phormia regina. RESULTS: A 2% chitosan solution was fed to adults of Musca domestica, Tabanus nigrovittatus, and Phormia regina to study the effects on survivorship. In all species, the uptake of chitosan caused a significant decrease in survivorship. Examination of the digestive tract of house flies showed a thick material within the midgut, plus a shriveling of the midgut only in chitosan treated flies. Initially, we tested chitosan as a 2% solution with sucrose at a concentration of .125 M. Later, we thought that a 4.3% (0.125 M) sucrose concentration was not sufficient and that flies, especially house fly, could be dying from sugar-starvation. Thus, we tested house flies using a .292 M sucrose solution. A survivorship curve of adult house flies fed the .292 M sucrose and 2% w/v ascorbic acid showed that the effect of the chitosan solution was due to the chitosan and not the ascorbic acid. Intake experiments revealed that by day 2, chitosan treated house flies consumed significantly less of the diet compared to controls. CONCLUSION: Chitosan, a biopesticide, when fed to three species of adult flies produced severe mortality within 4-6 days of ingestion. A working hypothesis suggests that by day 2 of the chitosan diet there appears to be a malfunction of the digestive tract and possibly the midgut microbiome.