Population Monitoring, Egg Parasitoids, and Genetic Structure of the Invasive Litchi Stink Bug, Tessaratoma papillosa in Taiwan

SIMPLE SUMMARY: The litchi stink bug (LSB) was inadvertently introduced to Taiwan recently and has since become a severe pest with substantial economic losses. The aim of this study is therefore to improve our knowledge of this invasive pest through multiple approaches including population monitoring, surveillance of natural enemies, and population genetic analysis. Major findings include: (1) a population fluctuation trend that is largely similar to most native LSB populations, (2) a total of seven egg parasitoid species were discovered, two of which (Anastatus dexingensis and A. fulloi) being most abundant throughout the LSB infestation in Taiwan, and (3) the occurrence of multiple introductions of LSB to Taiwan. All these data represent a preliminary yet necessary step for the design of future integrated pest management strategies and would help mitigate negative impacts of this invasive pest in Taiwan. ABSTRACT: Here we assessed population dynamics, natural enemy fauna (with emphasis on egg parasitoid), and population genetic structure (based on mitochondrial DNA) of the invasive litchi stink bug (LSB), Tessaratoma papillosa in Taiwan. Our major findings include: (1) fluctuations of LSB in numbers of adults, mating pairs, and egg masses over a 2-year period in Taiwan generally resemble those in the native populations; (2) Anastatus dexingensis and A. fulloi are among the most dominant LSB egg parasitoids, with the former consistently outnumbering the latter throughout Taiwan; (3) the presence of two genetically distinct clades suggests LSB in Taiwan most likely derived from multiple invasions. All these data practically improve our understanding of this invasive insect pest, particularly its ecological and genetic characteristics in the introduced area, which represents critical baseline information for the design of future integrated pest management strategies.