Species diversity of larval parasitoids of the European grapevine moth (Lobesia botrana, Lepidoptera: Tortricidae): the influence of region and cultivar.
Résumé
The European grapevine moth, Lobesia botrana (Denis & Schiffermüller, 1775) (Lepidoptera: Tortricidae) is a major pest of grapevines responsible for great economic losses and frequent insecticide applications. Nevertheless, the use of parasitoids as potential biological control agents has received very little attention. In this study, we present results from a survey on parasitoid species collected from French and Swiss vineyards over a period of 2 years. Over 2000 larvae of L. botrana were collected from six grape cultivars out of which a total of 118 parasitoids emerged. Ten species were identified. Exochus notatus (Holmgren, 1858) (Hymenoptera: Ichneumonidae) was the most abundant species and has a wide geographical distribution. Another parasitoid species, Agrypon anxium (Wesmael, 1849) (Hymenoptera: Ichneumonidae), had never been described on L. botrana before and two others remain unidentified Goniozus sp. (Förster, 1851) (Hymenoptera: Bethylidae) and Apanteles sp. (Hymenoptera: Braconidae). Other species include Phytomyptera nigrina (Meigen, 1824) (Diptera: Tachinidae) as well as Campoplex capitator (Aubert, 1960), Diadegma fenestralis (Holmgren, 1860), Dicaelotus inflexus (Thomson, 1891) Itoplectis maculator (Fabricius, 1775) and Triclistus meridiator Aubert, 1984 (all Hymenoptera: Ichneumonidae). We observed substantial regional variation in species richness and also found that abundance and diversity of several parasitoid species varied as a function of geographical location and grape cultivar. The parasitism rate by E. notatus was for example affected by grape cultivar suggesting that biological control may be affected by the cultivar of the host plant. These results are discussed in the context of tritrophic interactions and focus especially on the role of grape cultivar on parasitoid richness. We also suggest potential development of native parasitoid species in the implementation of biological control programs against L. botrana.