Oviposition preferences of female Sirex nigricornis F. (Hymenoptera:Siricidae) in relation to differing moisture contents of Pinus echinata

The European woodwasp, Sirex noctilio F., was introduced into New York and Ontario in 2004.  In some areas where it has been introduced, it has caused extensive damage to pine stands.  Moisture content of pine may be a main driving force behind the success or failure of the woodwasp.  Pine bolts were wrapped in mesh and left at field sites.  Drilling behavior of female S. nigricornis, the only woodwasp native to Arkansas, was measured across three bolt (0.75 m log) treatments: 0, 15, and 30 days left in the field.  Sirex nigricornis females showed a preference of drilling in the freshest (0-day) bolts but larval development was only seen in 15-day old bolts.  The oldest (30-day) bolts were virtually ignored by females.  Current rearing methods suggest felling trap trees a month prior to emergence.  While these practices usually result in successful colonization by siricids, numbers of Sirex per tree vary suggesting current methods may not always be efficient.  Continued monitoring is a priority and it may be more effective if trap trees are created after initial emergence of adult siricids is observed.  Future experiments performed this fall will test if felling trees after initial emergence has a significant impact on oviposition and development of siricids.