Seasonal variation in parental care, offspring development, and reproductive success in the burying beetle, Nicrophorus vespillo

1. Beetles of the genus Nicrophorus reproduce on small vertebrate carcasses that they bury in the soil to provide the larvae with food. Usually, both parents cooperate in brood care by feeding and guarding their progeny. 2. In pairs of the common European species N. vespillo, the duration of car e depended on the time of year when the beetles reproduced. Both in 1990 an d in 1991, male and female parents stayed longer with their broods when rep roduction started in spring than when reproduction started in early or late summer. This was probably due to the longer development time of the larvae caused by lower temperatures in spring, because laboratory experiments sug gested a strong influence of temperature on both the duration of brood care and offspring development. 3. The number of adult offspring produced by a beetle pair did not vary amo ng different times of the year. 4. The median time required for offspring development, measured as time fro m burial of the carcass to emergence of young adults, was between 62 and 84 days. When the beetles reproduced in late summer, only about three-quarter s of the offspring left the soil and hibernated as adults. The remaining of fspring stayed underground and adults appeared on the soil surface the foll owing spring. They still showed the flexible cuticle typical of newly-hatch ed beetles, suggesting that they may have overwintered in a pre-adult stage .