Summary1. The Collembola is one of the important prey groups for generalist arthropod predators in agro-ecosystems. Dierences in the quality of available species may play a signi®cant 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 beetle Bembidion lampros was assessed in laboratory experiments. 2. Consumption capacity, egg production and the eciency of converting prey into eggs were used as quality criteria for beetle adults, kept on diets of the collembolans Isotoma anglicana, Isotoma notabilis, Isotomurus prasinus, Folsomia ®metaria and Lepidocyrtus cyaneus, with fruit¯ies Drosophila melanogaster used as a high quality comparison prey. Survival, developmental time and teneral adult weight were used as quality criteria for beetle larvae on diets of Isotoma anglicana, Isotoma notabilis, F. ®metaria, D. melanogaster and a starvation treatment. 3. Collembola were oered to adults in dead and live treatments to assess the cost of prey capture and handling in relation to prey quality. 4. Bembidion lampros ate more dead than live Collembola. Egg production declined over time on all collembolan diets, indicating a lower quality of all species compared with D. melanogaster, but there was considerable variation between species. The highest food conversion eciency occurred on F. ®metaria, L. cyaneus and D. melanogaster, while Isotoma notabilis could not be utilized by B. lampros for egg production. 5. Larvae completed development with low mortality on Isotoma anglicana and F. ®metaria, although there were dierences in developmental time. The two Collembola seemed to be of relatively higher quality for larvae than for adults. Signi®-cantly higher teneral weight occurred on a diet of D. melanogaster compared with the Collembola. 6. The eect of Collembola quality on the beetle fecundity and larval developmental time suggests that agricultural management for natural enemies, should aim to bene®t the species composition of the prey population.

Egg production by the cereal spider Erigone atra was used as a fitness parameter for evaluating the food quality of two species of Collembola: Folsomia fimetaria and Isotoma anglicana. Drosophila melanogaster was used as reference prey. We tested the hypothesis that due to differences in food quality, the two Collembola species would affect the reproduction of the spider differently. The quality ranking of the prey types turned out as: I. anglicana > D. melanogaster > F. fimetaria. With F. fimetaria alone, spiders were unable to maintain reproduction. E. atra was more efficient in utilising I. anglicana and D. melanogaster. Thus, daily consumption rates of I. anglicana were lower in spite of higher egg laying rates by E. atra. A mixed diet of F. fimetaria and D. melanogaster resulted in a lower reproductive output than a pure diet of D. melanogaster, indicating a toxic element in F. fimetaria. In the mixed diet F. fimetaria had a negative influence on the consumption capacity of the spider towards D. melanogaster, while D. melanogaster had a positive influence on the consumption capacity towards F. fimetaria. It is concluded that a high abundance of I. anglicana may support a high reproductive output of E. atra, while the presence, of F. fimetaria in fields may reduce the spider's reproductive output.

The larvae of Hermetia illucens are known to successfully bio‐convert a vast range of organic substrates into high protein and fat biomass, but little is known about the larval instars. During this research, larval head capsules and biomass growth were measured daily and the specific metabolic rate of larger instars were considered. The head capsule measurements revealed that H. illucens pass through 6 actively feeding larval stadia before entering the last nonfeeding but migrating 7th stadium. Larval growth follows a sigmoid curve with slowly accelerating growth in the earlier stadia and decelerating growth in the latest stadia. In contrast, development was fast until reaching stadium 6 and then slowed down. Accordingly, the specific metabolic rate was high in instars 3, 4 and 5 and reduced in instars 6 and 7.

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Vegetation data including plant cover, biomass, species richness, and vegetation height was sampled on a copper-contaminated field with total copper contents varying from 50 to almost 3,000 mg/kg soil. The field was covered by early succession grassland dominated by Agrostis stolonifera. Plant cover, biomass, species richness, and vegetation height generally decreased with increasing copper content, although the highest biomass was reached at intermediate copper concentrations. Multivariate statistical analyses showed that plant community composition was significantly correlated with soil copper concentration and that community composition at soil copper concentrations above 200 mg/kg differed significantly from community composition at lower copper levels. Comparison of single-species (Black Bindweed, Fallopia convolvulus) performance at the field site and in laboratory tests involving field soil and spiked soil indicates that the laboratory tests conventionally applied for risk assessment purposes do not overestimate copper effects. Interaction between copper and other stressors operating only in the field probably balance the higher bioavailability in spiked soil.