Submitted to: Ecological Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/8/2005
Publication Date: 8/20/2006
Citation: Bilu, E., Hopper, K.R., Coll, M. 2006. Host choice by aphidius colemani: effects of plants, plant-aphid combinations and the presence of intraguild predators. Ecological Entomology. 31:331-336. Interpretive Summary: Aphids or plant lice, because of their short life cycle, reproduce very rapidly and some species are important agricultural pests. Fortunately, many species are attacked by parasitic wasps and predatory insects, which limit their numbers and damage to agricultural crops. Parasitic wasps prefer to attack some aphid species on some host plants over other aphid species on other host plants. Both predators and parasitic wasps attack aphids, but interactions between parasitic wasps and predatory insects are poorly understood. Predators may prey on aphids parasitized by wasps, and thus interfere with impact of parasitic wasps on aphids. However, parasitic wasps might avoid plants with predators. In the research reported here, a major parasite of aphids did not avoid plants with a major predator. Thus these biological control agents might interfere with one another.
Technical Abstract: This study first measured the effect of plant (radish, pepper and wheat), aphid-plant combination (the green peach aphid MYZUS PERSICAE on pepper and radish, and the bird cherry-oat aphid RHOPALOSIPHUM PADI on wheat) and the host on which A. COLEMANI was reared (the cotton aphid APHIS GOSSYPII on cucumber, M. PERSICAE on radish and pepper and R. PADI on wheat) on host choice behaviour of the parasitoid and the performance of its offspring. Then, the effect of predator presence (COCCINELLA UNDECIMPUNCTATA larvae) on host preference of the wasps was tested. When reared on M. PERSICAE on either radish or pepper, wasps preferred the aphid-plant combination from which they had emerged. Wasps reared on A. GOSSYPII (naïve to all hosts offered) and R. PADI preferred to parasitize M. PERSICAE on radish and M. PERSICAE on either radish or pepper, respectively. R. PADI on wheat was the least preferred and also the least suitable host, as determined by offspring body size. Contrary to expectations, the presence of predators did not influence the host choice of A. COLEMANI, even when predator-free plants were offered nearby. Results indicate that wasps are more likely to remain in some host systems but not in others, even when facing risk of predation. Results are discussed in respect to field data and the relative importance of risk of predation and host preference to wasp fitness.