Ants are significant structural and agricultural pests, generating a need for human-safe and effective insecticides for ant control. Erythritol, a sugar alcohol used in many commercial food products, reduces survival in diverse insect taxa including fruit flies, termites, and mosquitos. Erythritol also decreases longevity in red imported fire ants; however, its effects on other ant species and its ability to be transferred to naïve colony members at toxic doses have not been explored. Here, we show that erythritol decreases survival in Tetramorium immigrans Santschi (Hymenoptera: Formicidae) in a concentration-dependent manner. Access to ad-libitum water reduced the toxic effects of erythritol, but worker mortality was still increased over controls with ad-lib water. Foraging T. immigrans workers transferred erythritol at lethal levels to nest mates that had not directly ingested erythritol. Similar patterns of mortality following erythritol ingestion were observed in Formica glacialis Wheeler (Hymenoptera: Formicidae), Camponotus subarbatus Emery (Hymenoptera: Formicidae), and Camponotus chromaiodes Bolton (Hymenoptera: Formicidae). These findings suggest that erythritol may be a highly effective insecticide for several genera of ants. Erythritol’s potential effectiveness in social insect control is augmented by its spread at lethal levels through ant colonies via social transfer (trophallaxis) between workers.

Mannitol, a sugar alcohol used in commercial food products, has been previously shown to induce sex-biased mortality in female Drosophila melanogaster when ingested at a single concentration (1 M). We hypothesized that sex differences in energy needs, related to reproductive costs, contributed to the increased mortality we observed in females compared to males. To test this, we compared the longevity of actively mating and non-mating flies fed increasing concentrations of mannitol. We also asked whether mannitol-induced mortality was concentration-dependent for both males and females, and if mannitol’s sex-biased effects were consistent across concentrations. Females and males both showed concentration-dependent increases in mortality, but female mortality was consistently higher at concentrations of 0.75 M and above. Additionally, fly longevity decreased further for both sexes when housed in mixed sex vials as compared to single sex vials. This suggests that the increased energetic demands of mating and reproduction for both sexes increased the ingestion of mannitol. Finally, larvae raised on mannitol produced expected adult sex ratios, suggesting that sex-biased mortality due to the ingestion of mannitol occurs only in adults. We conclude that sex and reproductive status differences in mannitol ingestion drive sex-biased differences in adult fly mortality.

The ability of polyols to disrupt holometabolous insect development has not been studied and identifying compounds in food that affect insect development can further our understanding of the pathways that connect growth rate, developmental timing and body size in insects. High-sugar diets prolong development and generate smaller adult body sizes in Drosophila melanogaster. We tested for concentrationdependent effects on development when D. melanogaster larvae are fed mannitol, a polyalcohol sweetener. We also tested for amelioration of developmental effects if introduction to mannitol media is delayed past the third instar, as expected if there is a developmental sensitiveperiod for mannitol effects. Both male and female larvae had prolonged development and smaller adult body sizes when fed increasing concentrations of mannitol. Mannitol-induced increases in mortality were concentration dependent in 0 M to 0.8 M treatments with mortality effects beginning as early as 48 h post-hatching. Larval survival, pupariation and eclosion times were unaffected in 0.4 M mannitol treatments when larvae were first introduced to mannitol 72 h posthatching (the beginning of the third instar); 72 h delay of 0.8 M mannitol introduction reduced the adverse mannitol effects. The developmental effects of a larval mannitol diet closely resemble those of high-sugar larval diets. This article has an associated First Person interview with the first author of the paper.

31Mannitol, a sugar alcohol used in commercial food products, induced sex-specific mortality in 32 the fruit fly Drosophila melanogaster when ingested at a single concentration (1M), and female 33 mortality was greater than male mortality. We hypothesized that sex differences in energy needs, 34 related to reproductive costs, contribute to increased mortality in females compared to males. To 35 test for the effects of reproductive costs, we compared longevity to 21 days of actively mating 36 and non-mating flies fed various concentrations of mannitol. We also asked whether mannitol-37 induced mortality was concentration-dependent for both males and females, and if mannitol's 38 sex-specific effects were consistent across concentrations. Females and males both showed 39 concentration-dependent increases in mortality, but female mortality was consistently higher at 40 all concentrations above 0.75M. Fly longevity to 21 days decreased further for both sexes when 41 housed in mixed sex vials (as compared to single sex vials), suggesting the increased energetic 42 demands of reproduction for both sexes may increase ingestion of mannitol. Mannitol fed to 43 larvae did not alter emerging adult sex ratios, suggesting that sex-specific mortality due to 44 mannitol occurs only in adults. 45Introduction 46 D-mannitol (henceforth mannitol) is a 6-carbon polyol produced via microbial 47 fermentation, particularly by yeasts, and is the most common naturally-occurring polyol in plants 48 and fungi [1][2][3][4]. Mannitol is commonly used as a sweet additive in consumer products as it is 49 only partially absorbed in the human small intestine without increasing insulin secretion or blood 50 glucose [1,5]. 3 51 Mannitol produces a variety of gastrointestinal, reproductive, and survival effects when 52 fed to other organisms [2,6-7]. Mannitol reduced survival and prevented adult female 53 reproduction in Pimpla turionellae ichneumonid wasps [7]. In contrast, mannitol stimulated 54 feeding behavior at low doses (72.6mM) in red flour beetles (Tribolium castaneum) and 55 increased the longevity of females in comparison to males [8-9]. In contrast, adult female 56Drosophila melanogaster fed 1M mannitol food showed significantly decreased longevity over a 57 seventeen-day trial in comparison to males [10]. 58 We hypothesized that the sex-specific effects of mannitol in D. melanogaster could be 59 caused by differing energetic demands between males and females. Oogenesis requires greater 60 protein intake [11][12], leading females to eat more food, more frequently [13][14]. Sex-specific 61 differences in survival between males and females could be due to differences in ingestion that 62 increase self-dosing of mannitol in females. To test this hypothesis, first we assessed if mortality 63 was concentration dependent in both males and females, suggesting dose-dependency, and if sex-64 specific differences in survival were consistent across concentrations. Next, we assessed if flies 65 differed in survival when cultured in sing...

Ingestion of the polyol mannitol caused sex-biased mortality in adult Drosophila melanogaster, but larval mortality was not sex-biased. High-sugar diets prolong development and generate smaller adult body sizes in D. melanogaster. We hypothesized that mannitol ingestion would generate similar developmental phenotypes as other high-carbohydrate diets. We predicted concentration-dependent effects on development similar to high-sugar diets when D. melanogaster larvae are fed mannitol, as well as a concentration-dependent amelioration of developmental effects if introduction to mannitol media is delayed past the third instar. Both male and female larvae had prolonged development and smaller adult body sizes when fed increasing concentrations of mannitol. Mannitol-induced increases in mortality were concentration dependent in 0 M to 0.8 M treatments beginning as early as 48 hours post-hatching. Larval survival, and pupation and eclosion times, were normal in 0.4 M mannitol treatments when larvae were first introduced to mannitol 72 hours post-hatching (the beginning of the third-instar); the adverse mannitol effects occurred in 0.8 M mannitol treatments, but at a lower magnitude. Female D. melanogaster adults prefer laying eggs on diets with high sugar concentrations, despite the negative effects on offspring performance. However, when given a choice, female D. melanogaster avoided laying eggs on mannitol-containing media that was otherwise identical to the control media, suggesting females perceived and avoided mannitol. In conclusion, the developmental effects of a larval mannitol diet closely resemble those of high-sugar diets, but adult female oviposition responses to mannitol in laying substrates are distinct from responses to other carbohydrates.