Translator Disclaimer
1 February 2005 Diaeretiella rapae Limits Myzus persicae Populations After Applications of Deltamethrin in Oilseed Rape
Author Affiliations +

In fall, Myzus persicae (Sulzer) (Homoptera: Aphididae) may exhibit population resurgence in winter oilseed rape in France. This resurgence may arise from pyrethroid treatments against Coleoptera (Psylliodes chrysocephala L.) that either kill parasitoids present during treatment or prevent recolonization by off-crop parasitoids. We studied the impact of Diaeretiella rapae (M’Intosh) (Hymenoptera: Braconidae) on populations of M. persicae when parasitoids were introduced on deltamethrin-treated plants at increasing intervals after treatment. Parasitoids were introduced 1, 2, 7, or 14 d posttreatment on individually caged plants infested with established populations of M. persicae. Aphids were counted 7, 14 and 21 d after parasitoid introduction. First, we observed that both the pesticide and the parasitoid reduced aphid population growth and that their effects were additive. Second, there was no mortality of parasitoids exposed to treated leaves in a device with a refuge area, and only 20% of mortality without the refuge area. Furthermore, deltamethrin residues had no effect on the reproduction of D. rapae females. Compared with the known toxicity of deltamethrin to D. rapae on glass, this low mortality may have been due to both the high liposolubility of deltamethrin (leading to a rapid diffusion of residues in the oilseed rape leaf cuticle) and to the existence of a refuge area. This work suggests that D. rapae could limit populations of M. persicae in the fall, even after pyrethroid treatment, because the presence of deltamethrin residues had little impact on the parasitoid.

Nicolas Desneux, Xavier Fauvergue, François-Xavier Dechaume-Moncharmont, Lucien Kerhoas, Yannick Ballanger, and Laure Kaiser "Diaeretiella rapae Limits Myzus persicae Populations After Applications of Deltamethrin in Oilseed Rape," Journal of Economic Entomology 98(1), 9-17, (1 February 2005).
Received: 1 August 2003; Accepted: 1 March 2004; Published: 1 February 2005

This article is only available to subscribers.
It is not available for individual sale.

Get copyright permission
Back to Top