Necrophagous Insects and Internal Temperature Synergistically Determine Duration of the Decomposition Process for...

Necrophagous Diptera larvae are usually the earliest carrion-visiting necrophages in terrestrial ecosystems. However, despite the significant contribution of dipteran larvae to the natural decomposition process of large mammals in the ecosystem, which are thought to have a significant impact on ecosystem function and stability, there are still many unknowns regarding the function of maggots during actual decomposition of carcasses in the field. This study investigates the role of necrophagous dipteran larvae in the decomposition of sika deer (Cervus nippon) carcasses in a temperate forest ecosystem while excluding vertebrate scavengers. We evaluated the effects of ambient internal temperatures and body weight on carcass decomposition. A total of 12 deer carcasses were monitored for weight loss and both temperature changes from September 2021 to June 2023. The findings indicate that the average time for a deer carcass to decompose to 30% of its original weight was approximately 14 days, significantly influenced by seasonal temperature variations and initial carcass weight. Internal temperatures within carcasses were observed to exceed ambient temperatures by 10°C-30°C. Furthermore, the shorter the duration after carcass placement for the body's internal temperature to rise significantly above the air temperature, the faster the body decomposes. These results support our hypothesis that metabolic heat generated by maggot masses enhances larval activity and accelerates decomposition. This study also reveals that while Diptera larvae can significantly contribute to decomposition under optimal conditions, vertebrate scavengers play an essential role in the overall decomposition process, particularly in colder months.