Food preference behavior of adult house flies (Musca domestica L.)

House flies are commonly associated with livestock facilities and urban waste and serve as mechanical vectors of diverse disease-causing microorganisms while foraging for food. Although flies are indiscriminate feeders, nutrient composition of food is important for both fly longevity and reproduction, especially for females who need to consume a protein-rich diet for egg production. In this study, we investigated whether house flies preferred food based on macronutrient composition, and whether food preference was affected by fly sex and/or mating status. In feeding assays, mated or unmated male and female flies (n=20) were separated by sex and offered four food types, each in 10% solution offered on cotton wicks: confectioner’s sugar (carbohydrate-rich), fat-free milk (protein-rich and moderate carbohydrate), egg yolk (protein and lipid-rich), and water (no nutrition). Foods were colored with nontoxic dye, and colors were rotated between replicates (n=4). Flies were dissected at 4 h post-exposure to determine the type of food(s) ingested. Overall, house fly sex significantly influenced food preference, where females preferred protein and carbohydrate-rich food while males preferred mainly carbohydrate-rich. Male house flies preferred to feed on sugar (98.74% probability) while females preferred milk (95.56% probability). Furthermore, 40.05% of females and 13.75% males foraged in multiple foods. There was no significant effect of mating status on the probability of food preference within each sex. This study suggests that bait-based fly control strategies may need to consider sex-specific preferences for various food attractants if aiming to target and control both male and female house flies.