Effect of different post-feeding intervals on the total time of development of the blowfly Lucilia sericata (Diptera: Calliphoridae)

By estimating the age of the immature stages of flies developing on a corpse, forensic entomologists are able to establish the minimum post-mortem interval. Blowflies, which are the first and most important colonizers, usually leave the cadaver at the end of the last larval stage searching for a pupation site. This period of development is referred as the post-feeding or wandering stage. The characteristics of the ground where the corpse was placed might be of notable importance for the post-feeding dispersal time: For pupariation the larvae prefer an environment protected from light and predators and may have a longer dispersal time in order to reach an appropriate pupation site. Hence, the dispersal time can vary and may influence the total time of development which may lead to an erroneous calculation of the post-mortem interval. This study investigates the effect of various post-feeding time intervals on the development of the blowfly Lucilia sericata at a temperature of 25°C. As larvae reached the post-feeding stage a pupariation substrate was offered at 0 and after 12, 24 and 48h. Only the larvae with a dispersal time of 24h (total time of development 325.2h; median) and 48h (total time of development 347.7h; median) showed a significantly longer total development time compared to the control group (total time of development 318.4h; median). The mortality rate did not differ between groups; however the flies that emerged from the group with a dispersal of 48h were significantly smaller indicating increased energy consumption during dispersal. The results of this study indicate that a prolonged post-feeding stage could increase the total developmental time of L. sericata which should be taken into consideration when interpreting entomological findings. The need for a serious examination of current rearing practices in forensic entomology laboratories is indicated because reference data sets for the time of development are usually produced by offering the post-feeding stage a substrate for pupariation immediately.     

Gender and the transition from school to work in belfast

This article is based on interviews carried out in 1991 with 122 school pupils between the ages of 15 and 18 from a Catholic working-class area characterised by high, long-term unemployment located in Belfast. It includes further research carried out in 1998. The article focuses on three main aspects of young people's lives: their intended career aspirations, their involvement in term-time employment while at school and their participation in paid work within the household. The article suggests that the transition from school to work plays a crucial role in the reproduction of gender relations. The article demonstrates the ways in which young people at times accept and at other times challenge taken-for-granted assumptions regarding traditional gender stereotypes.