Meeting Abstract
Observing arthropod colonization on bodies can provide investigators with valuable information on post mortem interval (PMI). Blow flies colonize bodies rapidly and are forensically useful on relatively fresh remains however necrophagous beetles with slower development may be more useful in cases with longer PMI. However, diet affects growth and in cases of drug related deaths, insects may experience second hand drug effects. Based on blow fly research we expected a depressive effect of both ketamine and xylazine on growth and development. Further, higher fat content in meat types was predicted to increase growth rate and decrease time to metamorphosis. We tested the effects of these drugs in different doses and combinations on beetle development over 9 weeks in 6 body regions (arms, legs, 2 trunk segments) of 18 lab rats. Rats were skinned, dried and assigned to 108 replicate tanks (~5x5x1”), each containing ten 1st instar skin beetle larvae (D. maculatus). Larvae were photographed weekly and measured (mm) using Image J. Emerging adults were weighed (g) and removed from tubbies as found. As expected, body region affected growth rate (ANOVA; p<0.0001 for both weeks), with the anterior trunk producing the largest larvae. Growth during weeks 1 and 2 showed dramatic effects (ANOVA; p<0.0112 week 1, p<0.0385 week 2), with the highest ketamine dose in combination with xylazine produced the largest larvae over both weeks. While increasingly larger doses of ketamine produced larger larvae, xylazine may buffer its effects, as combination treatments of lower ketamine dosages did not significantly differ from control groups. These results suggest that forensic investigations using beetles to determine PMI require understanding the fat content of the meat and the drug combination/dose present in the body.
