Biological studies on immature and adult stages of Attagenus fasciatus (Thunberg) (Coleoptera: Dermestidae)

Abstract Both food and environmental conditions affected the development of the immature stages of Attagenus fasciatus (Thunberg) including the number and duration of larval instars. Dry milk, dry yeast and a mixture of both (1:1) were tested as food for larvae at 35°C, 70–80% r.h. and 30°C, 50–60% r.h. The species completed development on dry milk and the mixture but failed to do so on dry yeast alone. The number of larval instars ranged from 8 to 14 at 35°C, 70–80% r.h., from 8 to 13 at 30°C, 50–60% r.h. on dry milk, and from 8 to 15 on the mixture under the former conditions. In all cases the earlier instars lasted for shorter periods than the later ones. The larval period on dry milk lasted 173.6 ± 60.8 and 198.4 ± 29.2 days at the higher and lower temperatures, respectively. On the mixture the larval period was 178.0 ± 74.5 days. The highest pupation and adult emergence rates were recorded on dry milk at 35°C, 70–80% r.h. The larval food, mating and the environmental conditions affected fecundity and longevity. Females lived longer than males and non-mated beetles of both sexes lived longer than mated ones. The longevity of adult beetles at 30°C, 50–60% was shorter than at 35°C, 70–80% r.h. The sex ratio was 1:1.