Abstract
The major task of a forensic entomologist is to determine an accurate post-mortem interval (PMI) by analyzing the development or succession of necrophagous insects and other arthropods on the
carcass. Blow flies (Diptera: Calliphoridae) are the first arrival at a death scene and are attracted to carcasses through volatile compounds emitted during different stages of decomposition. It is
therefore probable that flies can easily distinguish between chemical signatures of early and late decay stages. Blowflies respond to sugars, salts and water through the activation of specific chemoreceptor within the antennal, labellar and tarsal chemosensilla. These insects also detect deterrent stimuli through a specific "deterrent" chemoreceptor within their sensilla called the "fifth" cell. Several investigations of chemosensory sensilla in various insect groups have been performed
to date, but relatively little information involving forensically important fly species. Due to this deficiency, the purpose of this study was to investigate the electrophysiological responses of receptor neurons on the antennae, labium and tarsus of a forensically important blowfly (Calliphora vicina) to different doses of morphine in decomposing tissues as well as odors emitted from the underneath soil. Electrophysiological recor dings indicate that the best responding cell to morphine sulfate is the 5th cell "deterrent cell" in all stimulating sites but with different degrees of sensitivity. These results strongly suggest that morphine sulfate with its different doses has a significant repellent effect on the attractiveness of Calliphora vicina. These conclusions should be considered when estimating PMI otherwise under estimation will result.
Key words: Calliphora vicina, Chemoreceptor neurons, PMI |
