Population genetic structure of a recent insect invasion: a gall midge, Asynapta groverae (Diptera: Cecidomyiidae) in South Korea since the first outbreak in 2008

Abstract

Outbreaks of Asynapta groverae, an invasive mycophagous gall midge, in South Korea have been repeatedly reported since the first occurrence in 2008. This species is a nuisance to residents owing to its mass emergence from newly built and furnished apartments. Here, the levels of genetic diversity, divergence, and structure of invasive A. groverae populations were investigated to understand their ability to survive in novel locations. Population genetic analyses were performed on seven invasive populations, including the first outbreak, sporadically emerged, and two laboratory-isolated (quarantined) populations, using the mitochondrial COI sequences and the ten novel microsatellite markers developed in this study. Non-indigenous A. groverae managed to maintain their populations for 12 years despite decreased genetic polymorphisms resulting from multiple incidences of founder effects by a small number of colonists. Additionally, the advantageous sustainability of A. groverae in the particle boards from which they emerge suggests that human-mediated dispersal is plausible, which may allow for the successful spread or invasion of A. groverae to new locations. This study is one of the few examples to demonstrate that an insect species successfully invaded new regions despite exhibiting decreased genetic diversity that was maintained for a decade. These findings indicate that the high genetic diversity of the initial founding population and asexual reproduction would contribute to the successful invasion of A. groverae in novel environments.

Experimental evidence supports the ability of spotted lanternfly to hitchhike on vehicle exteriors as a mechanism for anthropogenic dispersal

“…Only one gravid female is needed to begin a population of a species in a new area, and SLF females can deposit multiple egg masses and lay hundreds of eggs in their lifetime [29]. While small initial populations often fail and go extinct from various demographic and environmental stochasticity, many successful invasive species began the establishment phase with low founding genetic diversity [57][58][59][60]. Together, this suggests that each of the dozens of SLF satellite populations that appeared in 2023 and in years prior could have resulted from a single or multiple introduction event due to the hitchhiking mechanism presented in this study and factors discussed above.…”