Leon G. Higley
Date of this Version
Strauss, B. 2019. Density and Mass Effect on the Development of Phormia regina. MS Thesis. University of Nebraska-Lincoln. Lincoln, NE.
Forensic entomology is the application of the study of arthropods to the criminal justice system. This is primarily done through the development of a post mortem interval (PMI) based the insect evidence present. A practitioner must be able to determine the age of the insect through temperature data. One factor influencing the temperature dependent development is gregarious behavior. Current literature describes a faster development rate due to an increase in feeding efficiency and temperatures produced by this aggregate. However, there is very little literature defining a minimum number needed to induce this effect and little to none on it for Phormia regina.
Two experiments were done to explore the effect of aggregation on P. regina juveniles. Both experiments used growth chambers set to 25°C and egg masses from lab reared colonies. The first experiment used two chambers with differing densities of larvae at 25, 50, 100, and 200 in 490ml plastic containers with 2cm of pine shavings. Larvae were reared on 2g of liver in 29.5ml plastic cups in the containers and liver was added as needed. Each container was subsampled with replacement every day to check the development of the larvae (10-25%) until adult eclosion. Aggregate temperatures were checked with a digital heat thermometer gun (TES) and probe throughout the duration of the experiment. No significant difference in development was observed.
The mass temperatures in experiment one did not cause a decrease in development time as reported by the literature and the 100 counts had a higher average than the 200s. Experiment two was designed to explore this by increasing the space provided from a 490 ml container to a 1.42L one and to increase the feeding cup size from 29.5ml to 88.7ml. 25 and 200 larvae were provided 5g of liver to feed on initially.. Development times were significant longer for the 200 counts in the third instar and caused a downstream effect.
Advisor: Leon G. Higley