Potential for Use of Erythritol as a Socially Transferrable Ingested Insecticide for Ants (Hymenoptera: Formicidae).

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.

Larval mannitol diets increase mortality, prolong development and decrease adult body sizes in fruit flies (Drosophila melanogaster).

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 concentration-dependent 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 sensitive-period 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 post-hatching (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.

Mannitol ingestion causes concentration-dependent, sex-biased mortality in adults of the fruit fly (Drosophila melanogaster).

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.