EFFECTS OF HOUSEHOLD CHEMICAL POLLUTION ON CARCASS DECOMPOSITION AND NECROPHAGOUS INSECT DYNAMICS IN NORTHERN EGYPT

Abstract

This study evaluated how household chemical contamination affects carcass decomposition and necrophagous insect activity under natural conditions in Kafrelsheikh, a major agricultural region in northern Egypt. Three common chemicals—sodium hypochlorite (Clorox), hydrochloric acid, and formalin—were applied to guinea pig carcasses either by surface dipping or deep tissue injection. Key ecological metrics, including odor emission, decomposition rate, insect succession, larval development, and species diversity were assessed. Statistical analysis was conducted using Kaplan–Meier survival curves, Cox proportional hazards models, generalized linear models (GLMs), and two-way ANOVA. Formalin injection nearly halted both decomposition and insect colonization, while hydrochloric acid caused moderate delays. In contrast, sodium hypochlorite had minimal impact on decomposition or insect diversity. Insect emergence was significantly delayed in injected carcasses, and species richness was reduced, with Shannon diversity index values as low as 0.33 ± 0.67 in the formalin-injected group compared to 1.51 ± 0.83 in controls. Larvae from chemically treated carcasses were also significantly smaller, with formalin-injected specimens averaging 0.04 ± 0.01 g in weight and 0.6 ± 0.1 cm in length, compared to 0.12 ± 0.02 g and 1.5 ± 0.3 cm in the control group (p < 0.001). These findings highlight the disruptive impact of common household pollutants— particularly when injected—on natural decomposition and insect-mediated ecological processes. The results have direct implications for forensic investigations, environmental risk assessment, and region-specific decomposition models in chemically contaminated settings.