Diets of erythritol, xylitol, and sucrose affect the digestive activity and gut bacterial community in adult house flies

Abstract

AbstractPolyol sweeteners, including erythritol and xylitol, have been investigated for their potential in insect control against a number of pests including mosquitoes, fruit flies, ants, and filth flies. Several insecticidal modes of action for the polyols have been proposed in non‐biting flies and include: (1) dehydration from excessive regurgitation, (2) arrestment of physiological processes due to abnormally high hemolymph osmolality or osmotic diarrhea, and (3) alteration of the gut microbiome. Here, we explored the proposed modes of action in the house fly, Musca domestica L. (Diptera: Muscidae), a non‐biting fly of medical and veterinary importance. House flies fed erythritol or xylitol regurgitated at a significantly higher rate when compared to flies that ingested sucrose. Flies that ingested sucrose solutions had higher hemolymph osmolality than erythritol but not xylitol, and deposited significantly more fecal spots than flies fed polyol solutions. Cultivable bacteria were least abundant in flies fed solutions of either sucrose or xylitol and most abundant in control flies provided water only. Of the potential modes of action tested, physiological stress from excessive post‐feeding regurgitation seems the likeliest cause of death related to polyol consumption. However, we cannot rule out a classical toxicological or biochemical mode of action from these results. Although the efficacy of polyols as active ingredients is still under debate, their use as other components in fly control products may be beneficial. Due to widespread resistance to a limited number of insecticidal chemicals registered for house fly control, it is important that new control chemicals be thoroughly assessed for usefulness.