人工食物含水量對大頭金蠅 (雙翅目：麗蠅科) 生長發育之影響

Abstract

Forensic entomology is a subject which uses insects or other arthropods to solve problems in crime investigation, especially estimate post-mortem interval (PMI). PMI is the time length between a person's death and discovery of carcass, getting a precise estimate of time interval can help narrowing down suspect target in criminal cases. Entomologists can usually find several dipteran insects laying eggs on corpses, such as blow flies; for example in Taiwan, Chrysomya megacephala is a dominant blow fly species. Nowadays, entomologists usually examine maggots’ body size to estimate the PMI, but the larval developmental condition could be affected by many biotic and abiotic factors. Water plays a leading role in the larval survivorship because the blow fly larvae are lack of exoskeleton to protect them from dry environment. Previous studies has mentioned that different food influence larval size, age and pupation rate; however those studies mainly focused on the nutrition content of their diet. To understand the effects of water content, experiments were designed to simulate the conditions to study the effect of food water content on maggot development. Results showed when maggots intake more water than usual, they can grow longer and heavier, then the consequences further affect the PMI estimation. In contrast, when food water content is not enough, not only the larval survivorship will drop down dramatically, but also they grow smaller. The pupal weight also increased when larvae feed on food of higher water content. Although more studies are needed to know how water influences insect development, water effect is too important to be ignored. The future goals of these experiments will try to use these data to adjust PMI estimates and apply on real cases.