The value of Collembola from agricultural soils as food for a generalist predator

Abstract

Summary1. The Collembola is one of the important prey groups for generalist arthropod predators in agro‐ecosystems. Differences in the quality of available species may play a significant role in the build‐up of a community of natural enemies. The value of some common epigeic and hemi‐edaphic Collembola as prey for adults and larvae of the carabid beetleBembidion lamproswas assessed in laboratory experiments.2. Consumption capacity, egg production and the efficiency of converting prey into eggs were used as quality criteria for beetle adults, kept on diets of the collembolansIsotoma anglicana,Isotoma notabilis,Isotomurus prasinus,Folsomia fimetariaandLepidocyrtus cyaneus, with fruit fliesDrosophila melanogasterused as a high quality comparison prey. Survival, developmental time and teneral adult weight were used as quality criteria for beetle larvae on diets ofIsotoma anglicana,Isotoma notabilis,F. fimetaria,D. melanogasterand a starvation treatment.3. Collembola were offered to adults in dead and live treatments to assess the cost of prey capture and handling in relation to prey quality.4. Bembidion lamprosate more dead than live Collembola. Egg production declined over time on all collembolan diets, indicating a lower quality of all species compared withD. melanogaster, but there was considerable variation between species. The highest food conversion efficiency occurred onF. fimetaria,L. cyaneusandD. melanogaster, whileIsotoma notabiliscould not be utilized byB. lamprosfor egg production.5. Larvae completed development with low mortality onIsotoma anglicanaandF. fimetaria, although there were differences in developmental time.The two Collembola seemed to be of relatively higher quality for larvae than for adults. Significantly higher teneral weight occurred on a diet ofD. melanogastercompared with the Collembola.6. The effect of Collembola quality on the beetle fecundity and larval developmental time suggests that agricultural management for natural enemies, should aim to benefit the species composition of the prey population.