Abstract

Simple Summary Flies are frequently used as indicators of environmental health because their development is susceptible to stress. In this study, we analyzed wing shape variation to identify subtle asymmetries that occur when organisms are exposed to chemical stressors in agricultural landscapes. Our results indicated that individuals from areas with greater exposure displayed higher levels of asymmetry, which reflects developmental disturbances. This finding demonstrates that wing shape asymmetry can serve as a simple, cost-effective, and reliable method for monitoring the hidden impacts of agricultural chemicals on living organisms and ecosystem health.Abstract The widespread but often poorly regulated use of pesticides has triggered urgent debates on their hidden effects beyond resistance in target pests. This study investigates the morphological effects of pesticide exposure, specifically the organophosphate chlorpyrifos, using geometric morphometrics to assess fluctuating asymmetry (FA) in wing shapes of houseflies. Developmental stability (DS), the capacity of an organism to maintain an optimal phenotype under stress, serves as a key indicator of environmental and genetic stress. Flies collected from pesticide-exposed areas in rural areas in Chile (Arbolillo) exhibited significantly higher wing asymmetry than those from less exposed zones, reflecting developmental disturbances caused by chlorpyrifos. These findings emphasize the potential of FA as a biomarker for pesticide-related environmental stress. By linking pesticide exposure to measurable phenotypic disruption, this study calls for urgent integration of morphometric and genomic tools to better understand resistance mechanisms, while also promoting sustainable pest management practices. Our findings demonstrate that even a common insect like the housefly can serve as a biological sentinel, warning of broader ecological and public health risks in pesticide-dominated landscapes.