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United States Department of Agriculture

Agricultural Research Service

Research Project: CLASSICAL BIOLOGICAL CONTROL OF INSECT PESTS OF CROPS IN THE NORTHEASTERN U.S. Title: Hosts are more important than destinations: What genetic variation in Microctonus aethiopoides (Hymenoptera: Braconidae) means for foreign exploration for natural enemies

Authors
item Phillips, Craig - AGRESEARCH N. ZEALAND
item Vink, Cor - AGRESEARCH N. ZEALAND
item Blanchet, Arnaud - ARS EBCL
item Hoelmer, Kim

Submitted to: Molecular Phylogenetics and Evolution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 5, 2008
Publication Date: August 12, 2008
Citation: Phillips, C.B., Vink, C.J., Blanchet, A., Hoelmer, K.A. 2008. Hosts are more important than destinations: What genetic variation in Microctonus aethiopoides (Hymenoptera: Braconidae) means for foreign exploration for natural enemies. Molecular Phylogenetics and Evolution. 49:467-476.

Interpretive Summary: Classical biological control involves introducing natural enemies to new regions to help suppress pests. Historically low success rates in establishing natural enemies in new regions and in suppressing the targeted pests have often been attributed to failures of introduced populations to adapt to their new environments. To provide knowledge about the causes of intraspecific variation in a natural enemy for the purpose of improving success rates and minimising environmental risks in classical biological control, nucleotide sequence data were generated to assess genetic variation within Microctonus aethiopoides, a Palaearctic parasitoid of the weevil pests Sitona discoideus, S. hispidulus and Hypera postica in populations at two nearby locations in southern France. The molecular data provided strong support for the presence of at least two M. aethiopoides biotypes, one associated with Hypera species and the other with Sitona species. These new results combined with previously published data from 14 countries show that M. aethiopoides genetic variation is much more strongly correlated with host species than with sampling location and may explain the widely varying results that have been obtained from introducing M. aethiopoides to Oceania and North America for biological control. The results strongly suggest that success rates and environmental safety in biological control would be improved by ensuring that parasitoids collected in the native range are reared from the same host species that is being targeted for control in the region of introduction.

Technical Abstract: Nucleotide sequence data were generated from the gene regions COI, 16S, and arginine kinase to assess genetic variation within the Palaearctic parasitoid, M. aethiopoides, reared from Sitona discoideus, S. hispidulus and Hypera postica collected from two proximate locations in Mediterranean France. Partitioned Bayesian phylogenetic analyses of the molecular data provided strong support for the presence of at least two M. aethiopoides biotypes, one associated with Hypera species and the other with Sitona species. These new results combined with previously published data from 14 countries show that M. aethiopoides genetic variation is much more strongly correlated with host taxon than with sampling location. This contrasts with earlier perceptions that M. aethiopoides exhibits significant geographic variation, and may explain the widely varying results that have been obtained from introducing M. aethiopoides to Oceania and North America for biological control. The results strongly suggest that success rates and environmental safety in biological control would both be improved by ensuring that parasitoids collected in the native range are reared from the same host species as the one being targeted for control in the region of introduction. The results also provided insights both on the evolution of host range and on the evolutionary transition between solitary and gregarious larval development in M. aethiopoides.

Last Modified: 12/22/2014
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