In 2006 and 2008, two pig carcasses were exposed in an open field in northern Italy at the beginning of November and left out until complete skeletonization. The purpose of this study was to observe the necrophilous insects active during winter and their developmental time, highlighting potential temperature-related differences. Both carcasses were exposed in direct sunlight; entomological samples were initially taken twice a day and then less frequently. Immature stages were in part preserved in EtOH and in part reared in lab; environmental data were recorded and compared to the ARPA weather station data. Winter 2006 was mild and wet while winter 2008 was cold and snowy. The carcass exposed in 2006 was immediately colonized by Diptera which laid eggs continuously because the mild temperatures. The most abundant species in the first phases were Calliphora vicina, Calliphora vomitoria, Lucilia Caesar and Lucilia sericata, while in the most advanced phases the genera Fannia and Piophila were observed. The pig exposed in 2008 was colonized almost exclusively by a single species, Calliphora vicina; in the spring, this was replaced by Calliphora vomitoria and Piophila casei. During the first weeks, the temperature was still mild; then the temperature dropped and stayed very low until February. This period was characterized by lots of snow that accumulated around the carcass. Oviposition continued until late November and then there was no activity until March when the temperature rose. The maggots born from the first ovipositions developed inside the carcass and their development was so slowed down that it appeared almost synchronous. Therefore, it was possible to observe maggot migration from the carcass as masses of post-feeding maggots were collected in the pitfall traps around the carcass and their pupation sites were easily identified. The simultaneous emergence of young adults from their underground puparia was also observed.
Temperature induced diapause in Calliphora vicina maggots observed during a field experiment
LAMBIASE, SIMONETTA
2012-01-01
Abstract
In 2006 and 2008, two pig carcasses were exposed in an open field in northern Italy at the beginning of November and left out until complete skeletonization. The purpose of this study was to observe the necrophilous insects active during winter and their developmental time, highlighting potential temperature-related differences. Both carcasses were exposed in direct sunlight; entomological samples were initially taken twice a day and then less frequently. Immature stages were in part preserved in EtOH and in part reared in lab; environmental data were recorded and compared to the ARPA weather station data. Winter 2006 was mild and wet while winter 2008 was cold and snowy. The carcass exposed in 2006 was immediately colonized by Diptera which laid eggs continuously because the mild temperatures. The most abundant species in the first phases were Calliphora vicina, Calliphora vomitoria, Lucilia Caesar and Lucilia sericata, while in the most advanced phases the genera Fannia and Piophila were observed. The pig exposed in 2008 was colonized almost exclusively by a single species, Calliphora vicina; in the spring, this was replaced by Calliphora vomitoria and Piophila casei. During the first weeks, the temperature was still mild; then the temperature dropped and stayed very low until February. This period was characterized by lots of snow that accumulated around the carcass. Oviposition continued until late November and then there was no activity until March when the temperature rose. The maggots born from the first ovipositions developed inside the carcass and their development was so slowed down that it appeared almost synchronous. Therefore, it was possible to observe maggot migration from the carcass as masses of post-feeding maggots were collected in the pitfall traps around the carcass and their pupation sites were easily identified. The simultaneous emergence of young adults from their underground puparia was also observed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
