부산대학교 도서관

The habitat range of the native widow spider, Latrodectus elegans Thorell, is limited to the Yaeyama Islands (Okinawa Prefecture) in Japan, and its sharp population decline may be due to pesticides exposures and changes in the agricultural landscape. In our survey, a single female of L. elegans and its 6 egg cases were collected on Hateruma-jima Island for the first time since 2001. Unfortunately, the invasive brown widow spider, L. geometricus Koch (8 females and 42 egg cases), which is declared a noxious species in the Invasive Alien Species Act of Japan, was simultaneously collected for the first time from this island. Competitive exclusion of L. elegans by L. geometricus is a concern because they share a similar niche. Therefore, it is essential to carefully monitor the population dynamics of these two widow spiders for the conservation of L. elegans.