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

Abstract

Polyol 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.

Chitosan diet alters the microbiome of adult house flies

“…However, when the sugar baits would be mixed in with sucrose, the insecticidal effectiveness had a life-extending effect. There are suggestions leading towards fly dehydration or caloric starvation that could be affecting longevity, however there are other literature that suggest that these sugar alcohol diets decrease the bacterial communities due to their antimicrobial properties or effects of biofilm development (Uhari et al, 2000; de Cock et al, 2016; Burgess et al, 2018; Burgess et al, 2021). More research needs to be done to determine the mode of action of carbohydrates that affect fly longevity.…”

Emesis or regurgitation? Crop response to the ingestion of insecticide‐bait blends in Anastrepha ludens

“…It seems that flies detected the malathion and increased the regurgitation in response, apparently as a process of emesis as is seen in vertebrates (Horn, 2008). In recent studies, it was determined that the apparently innocuous polyols stimulate fly regurgitation to fatality levels in A. ludens , A. obliqua , D. suzukii , and M. domestica (Díaz‐Fleischer et al, 2019; Burgess et al, 2021). Together with what we found here with malathion, this suggest that flies have the capability to expulse harmful substances that may accompany some meals.…”

Erythritol sprays reduce Drosophila suzukii infestation without impacting honey bee visitation nor fruit quality

“…25 In house flies, erythritol ingestion causes excessive regurgitation. 20 In D. suzukii, erythritol elicits the gustatory receptor neurons 26 and can enhance lethality when added to marginally effective insecticides. 27 Ingesting erythritol interferes with osmolar balance causing D. suzukii to desiccate 28 and reduces their oviposition rate, even when females have ample egg loads.…”

“…Erythritol is an artificial sweetener registered for human consumption but toxic to D. suzukii 15,16 . Erythritol is also toxic to other Drosophila , 17 tephritid flies, 18,19 house flies, 20 mosquitoes, 21,22 psyllids, 23 termites, 24 and spider mites 25 . In house flies, erythritol ingestion causes excessive regurgitation 20 .…”

“…Erythritol is also toxic to other Drosophila , 17 tephritid flies, 18,19 house flies, 20 mosquitoes, 21,22 psyllids, 23 termites, 24 and spider mites 25 . In house flies, erythritol ingestion causes excessive regurgitation 20 . In D. suzukii , erythritol elicits the gustatory receptor neurons 26 and can enhance lethality when added to marginally effective insecticides 27 .…”