Biological Control of Thrips

Abstract

As part of a study on the biological control of thrips pests in European greenhouses, a general literature review has been carried out on thrips parasitoids. Except for data already published on this group, information has been supplemented with data of yet unpublished records obtained by checking museum material and by personal communication, until December 1993. Thrips parasitoids all belong to the superfamily Chalcidoidea. Most of them are solitary endoparasitoids of larvae (Eulophidae) or eggs (Mymaridae, Trichogrammatidae) of thrips (Thysanoptera). Except for some odd species in the genus Thripastichus (Eulophidae: Tetrastichinae) and Pediobius (Eulophidae: Entedontinae), all larval parasitoids can be found in four closely related genera: Ceranisus, Goetheana, Thripobius and Entedonastichus (Eulophidae: Entedontinae). They all are solitary, internal parasitoids of the larval stages, although sometimes the prepupae and/or pupae may be attacked. Parasitoids belonging to the genus Megaphragma (Hymenoptera: Trichogrammatidae) and Pediobius indicus (Hymenoptera: Mymaridae) are known to parasitize thrips eggs. In this review data of genera and species are presented on the distribution, host range, host plant associations, biology and behaviour of thrips parasitoids and their effectiveness as control agent of thrips pests, including several new records. Based on this information, their effectiveness is evaluated and specified pre-introduction criteria are formulated for selection of parasitoids as potential biological control agents of thrips pests, in particular those occurring in European greenhouses. Information on parasitoids is scattered and very incomplete, both on biology and taxonomy. A taxonomic revision of thrips parasitizing genera and species is therefore strongly recommended.