Study on the biological characteristics of the new invasive pest, Hylurgus ligniperda, in China

Hylurgus ligniperda is a major international quarantine pest, native to the southern Mediterranean coast of Europe and northern Africa, and causes significant damage in invaded areas. In 2020, it was first confirmed to be established and causing harm in Yantai City, Shandong Province, China, primarily infesting Japanese black pine (Pinus thunbergii). Owing to environmental and climatic differences, the biological and ecological traits of this new invasive pest may undergo changes in newly colonized regions, potentially diverging from those observed in its native range. This study aimed to elucidate the biological characteristics of H. ligniperda in its newly invaded range. Based on the establishment of artificial breeding techniques for this pest, this study combined field dissections with multiple indoor rearing methods, to investigate its biological characteristics in Yantai, Shandong Province. A simple and efficient artificial breeding method was developed using phloem bark powder and purified water. The study confirmed that H. ligniperda completes three generations annually in Yantai. The first generation emerges from overwintering adults in early May, with mass adult dispersal observed. May and June represent the peak period for oviposition and larval emergence. The second generation oviposits in July and August, and even after the third generation emerges in September, some adults continue to lay eggs. H. ligniperda primarily overwinters as adults and larvae, exhibiting overlapping generations. Observations of external morphological traits and ovary dissections revealed that the coloration of both male and female adults changes with age post-emergence: approximately 15 days after emergence, their color transitions from yellowish-white to reddish-brown, then to brown, and finally to black. Females reach sexual maturity around 10 days after emergence. This study preliminarily elucidates the life cycle, growth, and developmental duration of H. ligniperda in the invaded region, providing a theoretical foundation for effective management and containment of its further spread.