The impact of landscape diversity on the seasonal abundance of Japanese beetles and stink bugs in soybean

Abstract: The landscape around a soybean field can have a profound influence on the abundance and diversity of the community of insects within it. For example, the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), has both a lower abundance and a higher occurrence of biological control by natural enemies in soybean fields with higher surrounding landscape diversity. However, unlike A. glycines, Japanese beetles, Popillia japonica Newman (Coleoptera: Scarabaeidae) and herbivorous stink bugs (Heteroptera: Pentatomidae) are highly polyphagous and have relatively few native natural enemies. Therefore, the relationship between their abundance in a soybean field and the surrounding landscape diversity may be reduced or even in opposition to that of A. glycines. Beginning in 2012 we initiated a study to determine the effects that the surrounding landscape diversity may have on the first arrival and seasonal abundance of these two insect pest groups in soybean. To evaluate this relationship, we are sampling Japanese beetles and stink bugs in soybean fields around the state of Iowa surrounded by landscapes with a high degree of diversity (>50% non-crop habitat) and fields surrounded by landscapes with lower amounts of diversity (<10% non-crop habitat) within a 2 kilometer buffer. We have identified six fields within each type of landscape. The seasonal abundance of these insects will be determined by direct observation and sweep net sampling.