Abstract
House flies (Musca domestica) are a major nuisance pest and pathogen vector that continues to affect humans and animals in both urban and agricultural areas globally. Their ability to quickly reproduce makes controlling most populations a difficult task. House flies develop in decomposing organic substrates, which are amply available at sites such as animal production facilities and areas where urban refuse accumulates, such as homes and restaurants. Common practices used to manage house fly populations include the use of insecticides, traps, repellants, and biological control organisms. Insecticides generally are the preferred management method because they are cost-effective and easy to apply, but when overused can result in the evolution of resistance among adult house fly populations. Commonly used insecticidal products for house fly management include formulated ingestible baits that can be spread topically on the ground surface. This method however, may result in off-target exposures to organisms that find these products attractive, as well as developing larval house flies within the substrate on which they are applied. Although unintended, larval exposure to baits may elicit an evolutionary response in the level of resistance in a population of house flies, representing a previously unrecognized, and therefore novel, pathway for the evolution of resistance. The primary objective of this study was to determine the potential effects of insecticidal bait exposure during larval development on the evolution of resistance in the house fly. To accomplish this, house fly larvae were reared in growth media that was contaminated with the insecticidal bait, Quickbayt®, to determine if selection for the evolution of resistance in adults could be accelerated by this pathway. To test this hypothesis, adult house flies were evaluated after every two generation-based selection procedures for changes in survival duration while being exposed to Quickbayt®. My results indicated that larvae were able to withstand increasing concentrations of Quickbayt® each generation. However, this did not result in decreased adult susceptibility as was originally expected. The findings of this study regarding the novel, non-target effect of insecticidal bait exposure use as a pathway to accelerate the evolution of resistance and product failures will be further discussed.