Aboveground herbivory affects indirect defences of brassicaceous plants against the root feeder Delia radicum Linnaeus: laboratory and field evidence

• Published in: Ecological entomology Vol. 36; no. 3; pp. 326 - 334
• Main Authors: PIERRE, PRISCA S., DUGRAVOT, SEBASTIEN, FERRY, ANTONIN, SOLER, ROXINA, VAN DAM, NICOLE M., CORTESERO, ANNE-MARIE
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.06.2011; Wiley
• Subjects: Aboveground-belowground interactions; attraction; Brassica spp; cabbage plants; Delia radicum; entomopathogenic nematodes; host location; host-plant; indirect plant defense; induced volatiles; infochemical use; insect herbivores; Life Sciences; natural enemies; Pieris brassicae; plant-insect interactions; specialist herbivore; Trybliographa rapae; Trybliographa rapae; RELATION PLANTE-INSECTE; Delia radicum
• ISSN: 0307-6946; 1365-2311
• DOI: 10.1111/j.1365-2311.2011.01276.x

1. Belowground herbivory has recently been shown to disrupt the host location behaviour of aboveground parasitoids and thereby impact plants indirect defences. Reverse interactions, on the other hand, have received little attention so far. 2. Lab and field studies were conducted to examine whether the presence of the leaf herbivore Pieris brassicae Linnaeus on brassicaceous plants influences the response of Trybliographa rapae Westwood, a specialist parasitoid of the root feeder Delia radicum Linnaeus. 3. The present results show that the attraction of the parasitoid towards host-infested plants disappeared when these plants were also infested by P. brassicae. This absence of attraction was observed both when the complete odour blend or only undamaged leaves from damaged plants were offered, emphasising the role of systemically induced volatiles for host location in T. rapae. 4. Furthermore, the field study revealed that parasitism levels dropped from 30% on root-infested plants to 4% on double-infested plants. 5. The present study is the first to confirm that reduced attraction to host-infested plants as a result of simultaneous attack by below- and aboveground herbivores translates into lower levels of parasitism in the field.