Overwintering populations of beetle larvae (Coleoptera) in cereal fields and their contribution to adult populations in the spring

摘要: Although the ecology and distribution of adult beetles on farmland has been studied extensively, rather little is known their immature stages. Many species are important predators crop pests considerable interest shown in providing overwintering refuges from which they may colonise spring. We present evidence that for at least one common species, possibly a second, populations larvae have overwintered open field major contributors to spring populations. During winter 1998, larval were collected by barriered pitfall traps cereal fields. winter, Carabidae most commonly caught, with surface-active Nebria brevicollis being numerous. These distributed randomly across fields an activity-density same order magnitude as adults caught subsequently June. Thus large proportion probably developed within field, than invading boundaries. This further supported since many early summer tenerals, indicating had recently hatched. For Pterostichus melanarius, catches much lower subsequent catches, but again high percentage just-hatched tenerals June suggested this numbers soil, confirming findings earlier studies. Larvae mostly active below soil surface, why few caught. If our suggestions about importance correct, then such should be taken into account when trying enhance carabid summer.