Blind validation of postmortem interval estimates using developmental rates of blow flies

This study evaluated the use of different degree day (DD) models, developmental thresholds and developmental data sources for estimating postmortem interval (PMI) based on developmental rates of blow flies (Diptera: Calliphoridae). Blow fly evidence was collected from three mock crime scenes and sent for blind analysis of PMI. PMI estimates were calculated using averaging, single sine, double sine, single triangle, and double triangle models of DD calculation with minimum developmental thresholds of 0, 6 and 10°C and Anderson\u27s, Byrd and Allen\u27s, Greenberg\u27s, Nishida\u27s and Kamal\u27s developmental data sets. These estimates were compared with the actual PMI to determine which combination of DD model, developmental threshold and developmental data provided the most accurate estimate. For all three cases, at least one method gave a PMI estimation that was within 1 day of the actual date of death. There was no variability between PMI estimated using the five models of DD calculation. Overall, as lower developmental threshold increased, the PMI interval estimates increased. Depending on the developmental data set used, increasing the lower developmental threshold caused some overestimations of the date of oviposition, with estimates given that were prior to the actual death. Future PMI estimates should include error ranges, so that overestimation of PMI is avoided

Incidence of honeydew in southern pine-hardwood forests: implications for adult parasitoids of the Southern Pine Beetle, Dendroctonus frontalis (Coleoptera: Scolytidae)

The incidence of homopteran honeydew was measured under pines and hardwoods located within 10 Dendroctonus frontalis Zimmermann infestations on the Talladega National Forest (Alabama) during summer, 2000. There were more honeydew droplets beneath hardwood trees compared to pines, but no difference beween D. frontalis infested and uninfested pines. The number of honeydew droplets per tree differed between sampling dates, likely due to the effect of mean weekly temperature and rainfall on homopteran populations. The presence of honeydew on hardwoods may explain why D. frontalis parasitoids forage in areas that lack hosts and suggests that the fecundity of D. frontalis parasitoids may not be limited by adult nutrition

New record of Chrysomya rufifacies (Diptera: Calliphoridae) in Canada: predicted range expansion and potential effects on native species

AbstractThis is the first report of the hairy maggot blow fly, Chrysomya rufifacies (Macquart), in Canada since its arrival in the continental United States of America in 1982. Specimens were collected from one swine (Sus scrofa L.) carcass in fall 2004 and again from six swine carcasses at three rural sites within the Windsor/Essex County region of southwestern Ontario in fall 2005. Based upon the biological characteristics of the species and the absence of specimens from spring and summer carrion-insect collections, it is suggested that C. rufifacies is present in southwestern Ontario during the fall season, after range expansion from the midcontinental United States of America during the spring and summer months. However, considering the projected increases in temperature due to global warming, establishment of C. rufifacies is predicted to extend well into southern Ontario and Quebec. Current and predicted distributions based upon the biological temperature requirements of C. rufifacies are depicted through geographic range maps. The potential economic and ecological impacts are discussed, with emphasis upon negative interactions between C. rufifacies and several native blow fly species, particularly Cochliomyia macellaria (Fabr.)., RésuméNous signalons pour la première fois la présence de la mouche de la viande à asticot velu, Chrysomya rufifacies (Macquart), au Canada, depuis son arrivée dans la partie continentale des États-Unis en 1982. Nos spécimens proviennent d\u27une carcasse de porc, Sus scrofa L., à l\u27automne 2004 et de six carcasses de porc à l\u27automne 2005 dans trois sites ruraux de la région du comté de Windsor-Essex dans le sud-ouest de l\u27Ontario. D\u27après les caractéristiques biologiques de l\u27espèce et l\u27absence de spécimens dans les collections d\u27insectes sur les charognes au printemps et à l\u27été, nous croyons que C. rufifacies est présent dans le sud-ouest de l\u27Ontario en automne après avoir augmenté son aire de réparition durant les mois de printemps et d\u27été à partir des régions centrales du continent aux États-Unis. Cependant, en tenant compte des augmentations prévues de température causées par les effets du réchauffement global, nous prédisons que C. rufifacies étendra son aire de répartition considérablement dans le sud de l\u27Ontario et du Québec. Nous présentons des cartes géographiques des répartitions actuelles et projetées de C. rufifacies d\u27après ses besoins biologiques de température. Nous discutons des impacts potentiels, économiques et écologiques, surtout des interactions négatives de C. rufifacies avec plusieurs espèces indigènes de mouches de la viande, en particulier avec Cochliomyia macellaria (Fabr.).[Traduit par la Rédaction

Implications of using development rates of blow fly (Diptera: Calliphoridae) eggs to determine postmortem interval

This research examined the eclosion times of blow fly eggs to determine whether eggs begin to develop at the time of oviposition, or in vivo. Eggs were obtained from laboratory colonies of Calliphora vicina Robineau-Desvoidy, Phaenicia sericata (Meigen) and Eucalliphora latifrons (Hough) and observed at 2-h intervals. All three species had eggs eclose earlier than the expected minimum of 22 h at 21°C. Precocious egg development occurred for 75% of the C. vicina egg mass, while 100% of the E. latifrons and P. sericata egg masses developed early. Subsequently, we denied an oviposition medium to fresh C. vicina and P. sericata colonies for 7 and 14 d and compared the eclosion times with that of eggs from colonies with a continual access to beef liver. In both species, no precocious egg development was observed as the eggs eclosed 3-4 h after the expected minimum time of eclosion in both treatments and control. Finally, we examined eclosion times of eggs laid by blow flies in the wild. Eggs laid in the wild by P. sericata and C. vicina also took 1-3 h longer to eclose than the expected minimum time of eclosion. Our first experiment demonstrated that eggs laid by a single female at one time, can eclose at a wide variety of times, ranging from 2 h to the expected 22 h after oviposition at 21°C. Our inability to repeat the early eclosion in the laboratory with new colonies, despite the denial of oviposition media, or in the wild under natural conditions, is reassuring to those using egg development and eclosion to determine elapsed time since death. Clearly this phenomenon is not common, and may be explained as an artifact of laboratory colonies that do not have a regular influx of wild blow flies.Key words: forensic entomology; medico-legal entomology; elapsed time since deat

Successional patterns of diversity in insect fauna on carrion in sun and shade in the Boreal Forest Region of Canada, near Edmonton, Alberta

AbstractWe examined the successional community of insect fauna on exposed carrion in shade and sun in the Boreal Forest Region of Canada, near Edmonton, Alberta, over a 3-year period. This paper focuses on results obtained in the final year of study. Recently killed pigs (Sus domesticus L.) were clothed and placed in direct sunlight or shade on 18 and 20 May 1999. There was no difference in start time or duration of decomposition stages between the two habitats. Species abundance differed between the sun and shade habitats for Protophormia terraenovae (Robineau-desvoidy) larvae (Diptera: Calliphoridae), Necrobia sp. adults (Coleoptera: Cleridae), Catops basilaris Say adults (Coleoptera: Leiodidae), Onthophagus nuchicornis (L.) adults (Coleoptera: Scarabaeidae), Heterosilpha ramosa (Say) adults and larvae (Coleoptera: Silphidae), Creophilus maxillosus (L.) adults (Coleoptera: Staphylinidae), and Ontholestes cingulatus (Gravenhorst) adults and larvae (Coleoptera: Staphylinidae). The orders Diptera and Coleoptera were important components of all communities and had the greatest diversity at both the family and the species level throughout succession. Overall species abundance within families was greater in the sun habitat than in the shade. Similar species dominated the sun and shade carcasses during early succession, but dominance was not clearly evident later in succession., RésuméNous avons examiné durant une période de 3 ans la succession des communautés d\u27insectes sur de la charogne exposée à l\u27ombre ou au soleil dans la région de la forêt boréale du Canada, près d\u27Edmonton, Alberta. Nous présentons principalement les résultats de la dernière année de l\u27étude. Le 18 et le 20 mai 1999, nous avons recouvert de vêtements des cochons domestiques (Sus domesticus L.) fraîchement tués et les avons placés soit en plein soleil, soit à l\u27ombre. Il n\u27y a pas de différence temporelle dans le début ni la durée des divers stades de décomposition dans les deux habitats. L\u27abondance des espèces diffère entre les habitats d\u27ensoleillement et d\u27ombre en ce qui regarde les larves de Protophormia terraenovae (Robineau-desvoidy) (Diptera : Calliphoridae), les adultes de Necrobia sp. (Coleoptera : Cleridae), les adultes de Catops basilaris Say (Coleoptera : Leiodidae), les adultes de Onthophagus nuchicornis (L.) (Coleoptera : Scarabaeidae), les adultes et les larves de Heterosilpha ramosa (Say) (Coleoptera : Silphidae), les adultes de Creophilus maxillosus (L.) (Coleoptera : Staphylinidae) et les adultes et les larves d\u27Ontholestescingulatus (Gravenhorst) (Coleoptera : Staphylinidae). Les diptères et les coléoptères sont des composantes importantes de toutes les communautés et possèdent la diversité la plus grande, tant au niveau des familles que des espèces tout au cours de la succession. Le nombre global d\u27espèces dans les familles est plus élevé dans l\u27habitat ensoleillé que dans l\u27habitat d\u27ombre. Des espèces semblables prédominent dans les carcasses à l\u27ombre et au soleil au début de la succession, mais la dominance est moins claire plus tard dans le processus.[Traduit par la Rédaction