Oviposition and development response of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae) to five crop seeds

The perilla seed bugs, Nysius plebeius Distant and Nysius hidakai Nakatani, are emerging pests of perilla crop in Korea. Here, we investigated the life-history variables of N. plebeius and N. hidakai on five commonly grown crop seeds: perilla [Perilla frutescens (L.) Britt.], sesame (Sesamum indicum L.), sorghum [Sorghum bicolor (L.)], proso millet (Panicum miliaceum L.) and foxtail millet (Setaria italic L.). Bug oviposition, total developmental period, adult emergence, adult longevity and adult weight of both Nysius species were determined in both choice and no-choice tests. The oviposition and development periods of N. plebeius and N. hidakai varied significantly among seed species. The most preferred seed species for oviposition were perilla seeds, followed by sesame, sorghum and foxtail millet, whereas proso millet seeds were the least preferred. The bugs development period was faster in perilla seeds, with higher adult emergence, greater adult longevity and heavier adult weight. The higher oviposition preference and faster development with longer longevity of both Nysius species on perilla seeds is probably due to the physicochemical and nutritional attributes of the seeds. This information may enable the exploration of resistant genetic materials and chemical traits associated with seeds for breeding programme. Further, the outcomes of this study are discussed in terms of bug's behavioural response to crop seeds and management strategy of Nysius species as alternative to chemical management.