Natural Resources, School of

 

Date of this Version

12-2013

Citation

Lein, M. (2013). Anoxia tolerance of forensically important calliphorids. MS thesis, University of Nebraska.

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of the Requirements For the Degree of Master of Science, Major: Natural Resource Sciences, Under the Supervision of Professor Leon G. Higley. Lincoln, NE: December, 2013

Copyright (c) 2013 Melissa Marie Lein

Abstract

Forensically important blow flies, Diptera: Calliphoridae, are among the first organisms to colonize carrion. After eggs hatch, the larvae of most blow fly species feed in an aggregation or “mass.” While in this mass larvae may experience periods of no oxygen (anoxia), little oxygen (hypoxia), or normal oxygen (normoxia), but the tolerance of blow fly larvae to severe hypoxic conditions is not known. I tested the anoxia tolerance of four species of calliphorids (Calliphora vicina, Cochliomyia macellaria, Lucilia sericata, and Phormia regina), using third stage larvae across five temperatures. Experiments were conducted by exposing larvae to pure nitrogen environments and determining mortality at set time intervals. All species show significant linear relationships between survival time and temperature under anoxic conditions. Of species tested, C. macellaria withstood the longest period of anoxia ( LT50 of 9 h at 20oC). In contrast, C. vicina was the least tolerant (LT50 of 2.2 h at 40oC). Overall, survival of P. regina showed the least response and C. macellaria showed the greatest response to temperature. Unlike some other insects, the larvae of the calliphorids tested, which included members of three subfamilies, were not tolerant of anoxic conditions. From these findings, it seems likely that hypoxia could be a significant limitation for maggots submerged in a maggot mass, particular with high maggot mass temperature. Forensically, these data provide a limit on potential larval survival on bodies that have been submerged or otherwise experienced hypoxia before discovery.

Advisor: Leon Higley