Survey of mermithid nematodes (Mermithida: Mermithidae) infecting fruit-piercing stink bugs (Hemiptera: Pentatomidae) in Japan

Mermithid nematodes (Mermithida: Mermithidae) infect and kill many different invertebrates and have been investigated for their potential as a biological control agent of insect pests. In this study, we conducted a survey of mermithid nematodes infecting fruit-piercing stink bugs (Hemiptera: Pentatomidae) in Japan. We collected fruit-piercing stink bugs in four different prefectures (Shizuoka, Mie, Tokushima, and Saga) and investigated the distribution and infection ratio by mermithid nematodes. The results indicate that the nematode infection ratio of Glaucias subpunctatus (Walker) was higher than that of Plautia stali Scott or Halyomorpha halys (Stal). Furthermore, significant differences in mermithid infection percentages were observed among regions and seasons, with the highest being in G. subpunctatus in Mie during May-June. Of note, all mermithid nematodes were isolated from stink bugs collected from plants, and no nematodes were isolated from stink bugs attracted to store lights. This implies that parasitism of mermithid nematodes may affect the behavior of the host stink bugs. Furthermore, we obtained DNA sequences and simple morphological characteristics for the nematodes isolated. This study indicates that the mermithid nematodes obtained from stink bugs belong in the genus Hexamermis.