Geographic origins and post-introduction hybridization between strains of Trioxys pallidus introduced to western North America for the biological control of walnut and filbert aphids.

Publication date: Available online 27 September 2016 Source:Biological Control Author(s): Jeremy C Andersen, Nicholas J Mills Strains of the exotic parasitoid wasp Trioxys pallidus were introduced on multiple occasions to the western United States resulting in successful classical biological control of aphids in walnut and filbert orchard systems. However, breakdowns in biological control services have been reported in recent years in both orchard systems. To aid in potential plans to stabilize these important biological control programs we investigated the individual origins of each strain that was introduced to and established in the western United States, and examined whether post-introduction hybridization between strains has occurred. We collected individuals from the native and introduced ranges of T. pallidus, performed genetic clustering analyses using 15 polymorphic microsatellite loci, and reconstructed a phylogeny and estimated haplotype networks based on the mitochondrial (mtDNA) locus cytochrome oxidase I (COI). Based on microsatellite loci we find that T. pallidus individuals can be assigned to one of three distinct genetic clusters, and based on mtDNA haplotypes, to one of two distinct clades/networks. The majority of individuals from California were assigned to the same genetic cluster as individuals collected in Iran, also with shared mtDNA haplotypes, while the majority of individuals from Oregon were assigned to a genetic cluster represented by only a s...
Source: Biological Control - Category: Biology Source Type: research