Sweeteners allulose and neotame for potential use in house fly baits

The house fly, Musca domestica , is a cosmopolitan filth fly pest common in agricultural and urban areas where decaying organic matter is available for larval development. Adult M. domestica are nuisances and vectors of disease. When sanitation, screens, and sticky fly strips fail to control house fly populations, insecticide baits are often used. The use of baits can lead to the evolution of resistance, including not only physiological resistance to the toxicant but also behavioural resistance to the phagostimulant and to the toxicant. Here, the non‐nutritive sweeteners neotame and allulose were examined for their suitability as replacement phagostimulants in insecticidal baits for house flies. Suitability was assessed using proboscis extension response (PER) and consumption experiments. Allulose was further examined for insecticidal activity. Dry neotame elicited no PER, and it would not easily go into solution, so it was not examined in solution. Both in dry form and in solution, allulose elicited some PER and consumption, but only half or less of what sucrose or fructose elicited. Flies fed allulose alone had lower survival rates than flies fed sucrose alone. When given both allulose and sucrose, flies survived at similar rates to flies only fed sucrose. Neotame is not recommended as a replacement phagostimulant in bait formulations. Allulose alone is not recommended as a replacement phagostimulant. It remains to be seen whether combining allulose with sucrose as the phagostimulant in baits would result in as much bait consumption as just sucrose. If so, it might be worth testing whether the combination could serve as a rotational phagostimulant to prevent behavioural resistance to sucrose from evolving.