Density, Temperature, and Comingled Species Affect Fitness within Carrion Communities: Coexistence in Phormia regina and Lucilia sericata (Diptera: Calliphoridae)

Development of Phormia regina at seven constant temperatures for minimum postmortem interval estimation

Phormia regina (Meigen, 1826) (Diptera: Calliphoridae) can colonize carcasses quickly, and its immature stages are reliable entomological evidence for the estimation of the minimum postmortem interval (PMImin). There are discrepancies in the developmental data from previous studies on P. regina, and the related PMImin indicators need to be refined. We investigated the accuracy of forensic entomological evidence using development durations, growth accumulated degree hours, and larval body length variations of P. regina at seven constant temperatures ranging from 16 to 34 °C. We also established development models such as the isomorphen diagram, thermal summation model, isomegalen diagram, and body length simulation equation to assist with PMImin estimation. The developmental duration of P. regina from egg to adult at 16, 19, 22, 25, 28, 31, and 34 °C was 840.8 ± 42.8 h, 580.1 ± 10.1 h, 390.4 ± 8.7 h, 316.8 ± 9.4 h, 291.4 ± 21.2 h, 238.4 ± 2.8 h, and 222.5 ± 5.2 h, respectively. The lower threshold temperature TL was 9.97 ± 0.50 °C, while the thermal constant K was 5052.7 ± 229 degree days. The lower developmental thresholds, intrinsic optimum temperature, and upper lethal developmental threshold obtained by the Optim SSI models were 13.15, 21.20, and 36.86 °C, respectively. This study aims to provide developmental models for P. regina aimed at common case-site temperatures in the northern provinces of China, which can be used for accurate PMImin estimation.

Lucilia silvarum Meigen (Diptera: Calliphoridae) Is a Primary Colonizer of Domestic Cats (Felis catus)

Lucilia silvarum Meigen (Diptera: Calliphoridae) is widespread throughout North America and Europe. Described in 1826, this blow fly was quickly associated with myiasis in amphibians, and to date has rarely been reported in carrion. There is limited data regarding the time of colonization of animals with fur and the interpretation of this data is difficult due to variation in the animal models used. During an examination of initial insect colonization of cats (Felis catus) with light and dark fur, twelve domestic short-haired cats were placed in cages 15.2 m apart in a grassy field in West Lafayette, Indiana, USA. Eggs from initial oviposition events were collected and reared to identify the colonizing species. Three species of Lucilia (Diptera: Calliphoridae), including L. silvarum, colonized the cats on the initial day of placement. In this study, L. silvarum was the primary colonizer of cats, and this may be the first study where a large number of L. silvarum were collected. Further studies should include development studies on L. silvarum to understand its life history and aid in time of colonization estimations. More work regarding the colonization of furred mammals is needed to further examine L. silvarum as a primary colonizer.