Dr. Leon Higley
Date of this Version
MacInnis, A. 2018. Competition among three forensically important blow fly species (Diptera: Calliphoridae): Phormia regina, Lucilia sericata, and Chrysomya rufifacies. MS Thesis, University of Nebraska-Lincoln, Lincoln, NE pp.55.
The aim of this study was to use interspecific competition between three species of blow flies (Diptera: Calliphoridae) to determine if interspecific competition might explain the successional patterns. A replacement series model was used for three species of blowflies: Phormia regina, Lucilia sericata, and Chrysomya rufifacies. A total of 20 maggots were used for each treatment and the proportion of each species was varied. The graphic evidence and the relative crowding coefficient of P. regina versus L. sericata indicated a significant competitive advantage of P. regina. One of the life history traits of L. sericata is that it oviposits on carrion without any delay, while P. regina delays oviposition on carrion by up to 24 hours. Differences in oviposition times might represent a mechanism for L. sericata to avoid potential competition. C. rufifacies are known predators on other maggot species in the presence of limited food. With P. regina versus C. rufifacies, the later killed all P. regina in mixed treatments, showing a huge competitive advantage. These two species do not overlap often because of seasonal distributions. However, with the warming climate, C. rufifacies is likely to occur later in fall, earlier in the spring, and to extend its range north, so these two species could find themselves overlapping in the future. Consequently, C. rufifacies is likely to present a strong selective force on P. regina, and competitive displacement of P. regina seems likely. The relative crowding coefficient and modified relative crowding coefficient did not show distinguishable differences in competition between L. sericata and C. rufifacies. L. sericata has been shown to form clusters away from predaceous maggots allowing a better chance for survival, which may account for the absence of predation by C. rufifacies. Finally, this study shows that replacement series models are a useful tool in measuring competition of blow flies, and interspecific competition between species might explain the life history traits used by forensic entomologists and could be useful in predicting future situations.
Advisor: Leon G. Higley