Trapping techniques for siricids and their parasitoids (Hymenoptera: siricidae and ibaliidae) in the Southeastern United States.
The recent introduction of Sirex noctilio F. (Hymenoptera: Siricidae) into North America has raised interest in native siricids and their parasitoids to better understand the potential impact of S. noctilio. In the southeastern United States, we assessed various techniques to capture native siricids and their parasitoids using traps, lures, and trap trees. During 2009-2011, in total, 2,434 wasps were caught including Eriotremex formosanus (Matsumura), Sirex nigricornis (F.), Tremex columba (L.), and Urocerus cressoni (Norton) (Siricidae), and Ibalia leucospoides ensiger Norton (Hymenoptera: Ibaliidae). Traps and trap trees, respectively, captured 14 and 86% of total siricids and hymenopteran parasitoids. Majority of siricids (76%) were caught in Louisiana, where 486 I. l. ensiger (28% parasitism rate) were also reared from trap trees. The Sirex lure alone and Sirex lure with ethanol captured two to five times greater numbers of siricids than unbaited traps. Trap types had no effect on catches of siricids. Fewer siricids were caught in traps baited with ethanol alone than in those baited with other lures in Georgia. We caught three to four times greater numbers of S. nigricornis in traps with fresh pine billets (with foliage) as a lure than traps baited with Sirex lure in Louisiana. More S. nigricornis and I. l. ensiger emerged from cut and felled trap trees created in early rather than late November; these trees also had 14 times greater emergence than those treated with Dicamba. Our results indicate that use of host material and timing may be important for monitoring populations and communities of siricids and their parasitoid species in southern pine forests.