Attractiveness of three weed species to polyphagous predators 
and their influence on aphid populations in adjacent lettuce cultivations

Abstract

The utilization of olfactory responses of predators and parasitoids to the allelochemicals emitted by phytophagous arthropods and their host plants is becoming more important in biological pest control. The effects of three weed species, i. e. wormwood Artemisia vulgaris L., tansy Tanacetum vulgare L. and stinging nettle Urtica dioica L., which were planted as accompanying vegetations into a lettuce field, were examined for the predatory species Coccinella septempunctata L., Adalia bipunctata (L.), Propylea quatuordecimpunctata (L.) (Coleoptera, Coccinellidae) and Chrysoperla carnea (Steph.) (Neuroptera, Chrysopidae), as well as for aphids during the summer of 2000. The presence of weeds significantly increased the density of adults and larvae of the predators on the lettuce plants in relation to the control (lettuce field without weeds). However, the differences remained smaller for eggs and pupae. C. septempunctata tended to be the most abundant species, followed by P. quatuordecimpunctata. Remarkable differences among the attractiveness levels of the weeds in the 3 treatments were not observed. The increased populations of predators were accompanied by significantly reduced infestation rates with aphids in the treatments in relation to the control. Myzus persicae Sulzer was in general the most abundant aphid species followed by Nasonovia ribisnigri Mosley and Macrosiphum euphorbiae Thomas. The results of the present study are discussed with respect to the management of agroecosystems and the use of weeds in biological control.

Food Relationships

“…These patches supported only low densities of pea aphids, apparently because of the local build -up in ladybird numbers. Similarly, Sengonca et al (2002) found that C. septempunctata , A. bipunctata and P. quatuordecimpunctata the landscape matrix in which individual fi elds of alfalfa occur (e.g. percentage of the surrounding landscape that is wetlands, woodlands or crops) can sometimes overshadow the direct numerical response of ladybirds ( Hip.…”

Use of ryegrass strips to enhance biological control of aphids by ladybirds in wheat fields

“…Muller and Godfray (1997) demonstrated an earlier population decline in nettle aphid colonies adjacent to grass plots as a result of migration. Accompanying weed strips with olfactorily attractive plants can also contribute to the promotion of predators (e.g., ladybirds) in biological pest control (Sengonca et al , 2002). Ryegrass is a type of forage grass that has some agronomic characters, such as abundant tillers, strong resistibility, and earlier maturation than wheat.…”

OMIA-RAPPORT 2: Omgevingskwaliteit en Ecosysteemdiensten: een conceptuele en praktijkgerichte vergelijking van twee systeembenaderingen

“… Wanneer natuurlijke vijanden niet kunnen overleven in de akkers en plantages moeten de semi(natuurlijke) habitats rond de akkers dienst doen als refugia. Verschillende studies hebben aangetoond dat de (semi)natuurlijke habitatfragmenten tussen de velden een diversiteit aan natuurlijke vijanden herbergen zoals loopkevers, kortschildkevers, spinnen, lieveheersbeestjes, zweefvliegen, gaasvliegen, roofmijten en -wantsen, allerlei parasitoïden en insectivore vogels (Varchola & Dunn, 2001;Maudsley et al, 2002;Sengonca et al, 2002;. Die (semi)natuurlijke habita ts zijn relatief ongestoord en permanent aanwezig waardoor ze dienst doen als een reservoir voor deze soorten.…”