Effects of some toxic heavy metals on larval growth rates of Calliphora vicina (Diptera: Calliphoridae) and estimation of PMI

Abstract

Determination of larval growth rate and forensic analysis of the age of blow fly larvae on a corpse are useful evidence in legal investigations for the estimation of PMI. However many factors, such as temperature, tissue type and contamination of drugs and toxins, effect larval development of blow fly larvae and consequently the estimation of PMI. The present study examined the larval growth rate of a forensically important blow fly species, Calliphora vicina Robineau-Desvoidy, 1830 in different concentrations (0,12; 0,25; 0,50; 1 and 2 µg/g) of some toxic heavy metals (Cd, Pb, Hg, Fe, Cu, Mn, Ni, Zn), under controlled laboratory conditions. Body length and weight, death ratio of larvae and pupa between experimental and control groups were compared. Results demonstrated that the development rate of larvae between uncontaminated and contaminated diets varies significantly. In short, they molted later, reached maximum length more slowly and sometimes produced significantly smaller pupae in contaminated food source. These results emphasized that the importance of determining the contamination rate of toxins in tissue for the forensic entomologist, while using development rates from standard curves based on larvae fed non-contaminated mediums.