Kenneth Schoenly. 1990. The predators of insects. Ecological Entomology 15: 333-345.

Abstract. 1. Insect–insectivore trophic relations were reviewed using presence–absence data from sixty‐one invertebrate‐dominated food webs and fifteen food webs from Briand's (1983) original forty web collection. From counts of prey links in higher taxa (orders, classes, phyla), six phyla and thirteen classes of non‐insect insectivores and fourteen orders of insect predators and prey were found.

2. Detritus‐based habitats (phytotelmata, felled logs, carcasses, dungpads) harboured fewer orders of insects, that interact with other insects, than webs from grazer‐based (host plants, some galls) and mixed‐based systems (aquatic webs). Consumer–resource networks of higher insect taxa in these webs shared several features found in some species‐level biological networks: the trend was towards few pairs of strong asymmetrical links, several weak links and many null interactions.

3. From counts of insect predator–insect prey links, hymenopterans as terrestrial predators and parasitoids interacted with the greatest number of higher insect taxa. Hymenopterans were also linked as prey more often than other terrestrial insects. In freshwater habitats, plecopterans were linked as predators more often than other aquatic taxa, whereas dipterans were listed as prey more often than other insects.

4. Dipterans were linked in the diets of non‐insect insectivores from seven of eight common taxonomic classes. Arachnids were identified as insect predators by food web researchers in the largest number of webs, followed by passerine birds and cyprinodont fishes. From analysis of prey links at the ordinal level, predaceous insects were less polyphagous than other predators (other ectotherms and endotherms).

5. Analysis of chain lengths, as expected, showed that insect prey occupied mostly lowermost trophic levels, non‐insect insectivores were found mostly at uppermost trophic levels, and predaceous insects were found mostly at intermediate trophic levels across most habitats.

6. This analysis offers evidence that insects are not just occupying intermediate trophic levels in some communities. Indeed, some taxa feed at the upper ends of long food chains, for example eupelmids in galls, staphylinids in carcasses, and perlid plecopterans in streams.

Vincent G. Nealis. 1990. Factors affecting the rate of attack by Cotesia rubecula (Hymenoptera: Braconidae). Ecological Entomology 15: 163-168.

Abstract. 1. The relationship between responses of the insect parasitoid Cotesia rubecula (Marshall) to kairomones produced by the feeding activities of its host, Pieris rapae (L.), and patterns of parasitism were investigated under field conditions.

2. Parasitoid adults aggregated in patches with the highest densities of host larvae but there was no commensurate increase in the rate of attack in these patches.

3. The rate of attack was not limited by the availability of eggs.

4. The rate of parasitoid attack was highest where feeding damage by the host was highest, irrespective of current host density.

5. The rate of parasitoid attack was further influenced by host age distribution. Late instar larvae were less susceptible to parasitism than were early instar larvae. The rate of attack on early instar larvae occupying the same plants as late instar larvae was reduced. This reduction in rate of attack was due to limitations on parasitoid search time imposed by the increased feeding damage associated with large host larvae and by the increased time the parasitoid required to recover from an attack on these large host larvae.

Keywords: food webs, arthropod predation, food chain lengths, top predators, insect communities, trophic structure, community ecology, predation is not one whose ecological consequences are obscure the inescapable fact that animals, including insects are either predators or prey, or both, ecologists and evolutionary biologists have historically focused attention on population-based properties of predation