Egg parasitoid survey of the redbanded stink bug (Piezodorus guildinii) in Louisiana soybeans

Stink bugs (Hemiptera: Pentatomidae) are major pests of soybean. The redbanded stink bug, Piezodorus guildinii (Westwood), is a neotropical species, ranging from Argentina to the US. Until recently, it was not considered an economic threat to US soybean production. Redbanded stink bug is now the dominant stink bug pest in the mid-South. In 2009 and 2010, a parasitoid survey of the redbanded stink bug was conducted. Each week, thirty plants were randomly collected and examined for the presence of stink bug eggs from four maturity groups at four locations. Plant height and the number of nodes were recorded for each plant. If stink bug eggs were present, the location on the plant, the stink bug species and the number of eggs were recorded. The eggs were returned to the laboratory and placed in a labeled Petri dish with a moistened filter paper and kept in a growth chamber at 25ºC, 60% RH and 14:10 [L:D]. The dishes were checked daily for either parasitoid or stink bug emergence. All emerged parasitoids were moved to vials containing 95% alcohol and identified to species using taxonomic keys. Preliminary data indicates that 30% of all redbanded egg masses collected were parasitized. Approximately 90% of emerged egg parasitoids were Telenomous podisi (Ashmead). Maturity groups III, IV and V resulted in about 30% parasitism of redbanded stink bug eggs, while maturity group VI resulted in 10% parasitism. This is the first survey of egg parasitoids for the redbanded stink bug in the US.