Annual pattern of occurrence of Riptortus pedestris (Hemiptera: Alydidae) and its egg parasitoids Ooencyrtus nezarae Ishii and Gryon japonicum (Ashmead) in Andong, Korea

Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) is one of the major pests of soybean (Glycine max [L] Merr.) in Korea and Japan. The occurrence of two important egg parasitoids of R. pedestris, Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) and Gryon japonicum (Ashmead) (Hymenoptera: Scelionidae), before and after soybean cultivation is poorly known. To record the seasonal occurrences of R. pedestris and parasitism during 2008-2010, aggregation pheromone traps baited with R. pedestris eggs were placed in a field in Andong, Korea where a series of crops, including barley (Hordeum vulgare L), sesame (Sesamum indicum L), and soybean, were cultivated during this study. R. pedestris was first recorded in the second week of April on barley and was most abundant in August on soybean. C. japonicum first appeared in May and was the dominant parasitoid until the first week of August on barley, sesame, and early soybean. From late August to September or October when soybean was cultivated, O. nezarae became the dominant parasitoid. The differential pattern of seasonal occurrence between the two parasitoids is discussed. (C) 2012 Elsevier Ltd. All rights reserved.