Behavioural responses of the European woodwasp, Sirex noctilio, to southern pine species

We assessed the oviposition and colonization preferences of Sirex noctilio Fabricius on southern pines. In 2009 and 2010, respectively, two (loblolly and Virginia), and six (loblolly, Virginia, white, slash, shortleaf, and longleaf) commercially important southern pine species were used. For the host choice experiment, 3-4 logs of each pine species (including Scots as control) in small and large diameter classes (in 2009) were placed in random locations within an arena. Males and females of S. noctilio were released in the arena. Observations on the activities of adult S. noctilio on logs were taken, and logs were individually enclosed for emergence. For the host no-choice experiment, 2-3 large diameter class logs of each pine species were individually enclosed, and male and female S. noctilio were introduced. Similar observations as the host choice experiments were taken. Host colonization data were taken from the logs, after adult S. noctilio finished emerging in fall 2009. Preliminary results for 2009 indicate that in the host choice experiment, significantly more males and females of S. noctilio were observed on Virginia pines. More females drilled with their ovipositor and emerged from Virginia pines, and more S. noctilio emerged from larger than smaller diameter logs. In 2010, we observed females of S. noctilio drilling on Scots, Virginia, loblolly, shortleaf and longleaf pines to varying degrees, indicating a host preference. Future work will determine antennal responses of female S. noctilio to bark volatiles; and assess differences in wood and resin quality of southern pines to explain host colonization patterns.