In agricultural ecosystems, wild plants such as weeds, can indirectly affect crops owing to phytophagous insects that feed on both wild plants and crops. In paddy fields, some heteropterans use their proboscis to feed on rice ears, which can cause “pecky rice” (black spots on the grain). Even a low percentage of pecky rice ( >0.1%) can reduce the market price of rice; this damage has caused farmers in Japan to suffer serious economic losses. Heteropterans that cause pecky rice may feed on the reproductive organs of weeds growing around the paddy fields. In most previous to determine the host plant range of each heteropteran species. However, using the sweeping method can lead to the accidental sampling of insects that do not feed on plants. In this study, to determine which species of weeds can increase the incidence of pecky rice via shared heteropterans, the relationships between heteropterans and host plants (Poales) were directly observed in an agricultural landscape (including paddy fields). The study was conducted in Hyogo, Japan, from June to October 2019. A total of 833 individuals of 27 heteropteran species (13 families) were recorded feeding on the reproductive organs of 35 plant species (including rice plants). Twelve heteropteran species were found on rice plants. Of these, nine species also fed on weeds (32 species). A variety of weed species that grow around paddy fields could provide food resources for heteropterans. Thus, such weeds may indirectly increase the incidence of pecky rice.
