Development of Cochliomyia macellaria on Equine and Porcine Striated Muscle Tissue and Adult Attraction to Larval Resource

Cochliomyia macellaria (Fabricius) has great importance in forensics and is commonly utilized in estimating the period of insect activity (PIA) on a corpse due to its rapid colonization time of fresh remains, active oviposition during daylight, and its abundance throughout the southern United States. The purpose of this study is to determine what effects tissue and temperature will have on C. macellaria. The purpose of my secondary studies on attraction to larval resource is to gain insight into the behavior of adult blow flies in order to determine what factors drive colonization of remains. Forensic entomology can use development data of calliphorid flies to estimate their PIA on human remains. C. macellaria has major implications in medico-legal entomology as well as in veterinary entomology and are often found on human remains in Texas during the warm months of the year. Furthermore, C.macellaria is a secondary myiasis producer; this means that its larvae may be found infesting living animal or human muscle tissue and potentially could be involved in veterinary forensic cases. This study will help provide better insight on the behavior of C. macellaria in Texas as it relates to tissue type and temperature. In this experiment larvae were reared at three separate temperatures (21?C, 24?C, and 27?C) on either equine or porcine striated muscle tissues. Eggs were inoculated onto each tissue and monitored every hour for hatch. Once hatch occurred, observations were shifted to every twelve hours. Three larvae were sampled during each observation period. Sampled larvae were weighed and length was recorded. Additionally, stage of development was determined. Pupae were collected and time to adult emergence recorded. Furthermore, life-history traits, such as emergence pattern and adult longevity, were recorded. This study is the first in Texas and second in the United States to examine the development of C. macellaria and could provide significant information for cases of myiasis and neglect of both humans and animals. In contrast, rearing flies on beef liver or pork chops, which tends to be a standard procedure often employed may not be applicable to myiasis cases of equines. Data from this study could provide greater insight to developmental differences of forensically important blow flies on striated muscle from different vertebrate species. Since porcine tissue was used in the Florida study, it was also utilized in our study in order to allow a comparison. To date there is only one data set on the development of C. macellaria in the United States. Fly populations in different climates are suspected to have different development rates. This study will compare data from central Texas to data generated in Florida. If variation of development rates is demonstrated for different populations, then forensic entomologists should use data that are more conducive to their given geographic area. My secondary objective first looked at whether larval resource had an attraction effect on the subsequent adult C. macellaria flies. One cohort of larvae was reared on bovine testicles, while another was reared on bovine liver. The subsequent adults were then tested in a dual-choice olfactometer which possessed testicles at one end and liver at the other end. The second set of experiments also involved using a dual-choice olfactometer; however, all larvae were reared on bovine liver and fresh liver was placed at one end of the olfactometer, while fresh liver with conspecific larvae was placed at the end of the other. The purpose of this experiment was to assess whether adult C. macellaria flies were more attracted to the presence of conspecific larvae. These experiments will give us more insignt into adult blow fly behavior and help us to understand what factors drive colonization of remains.