Introgression in invasive insects

Invasive insects cause billions of dollars in damage and prevention each year. Hybridization and introgression are potential consequences of species invasions that can lead to fitness advantages for the invasives such as increased temperature tolerance, pesticide resistance, or even lead to speciation events. Evidence of hybridization has been noted in several invasive insects including bollworms, fruit flies, leafminers, corn borers and aphids. Here, I present evidence of hybridization in two genera of aphids (Aphis and Myzus) and the Old World Bollworm. Aphids are tiny, mostly asexually reproducing insects that are often associated with crops or food products and thus easily transported across oceans or trade routes. Myzus (Aphidinae:Macrosophini) and Aphis (Aphidinae:Aphidini) both contain agriculturally important polyphagous aphids:. We generated whole genomic sequences and used publicly available sequence data to reconstruct species phylogenies with >5500 genes for each genus. Genome site-based and network-based hybridization/introgression statistical tests, together with the species phylogenies, provide strong evidence for additional occurrences of within-genus hybridization/introgression involving polyphagous invasive species in both Myzus and Aphis. The Old World bollworm caterpillar damages flowers and fruits from more than 180 plant species and has recently been documented in the United States. We demonstrate how hybridization has affected this group as well. These results support the hypothesis that polyphagous pest aphids are frequently hybridizing, which may lead to more successful invasions. Future analyses will focus on the effects of introgression/hybridization on known resistance genes and the presence of a fitness advantage for those taxa.