Phenology and flight periodicity of Sirex noctilio (Hymenoptera: Siricidae) in central New York, U.S.A.

Field and laboratory studies were performed to determine the phenology of flight activity and the thermal requirements for adult emergence of Sirex noctilio. Degree-day (DD) accumulation from egg to adult was measured in bolts of Pinus sylvestris infested with eggs from laboratory-reared adults. Adult emergence was similarly monitored in bolts from trees that were naturally infested in the field by wild populations of S. noctilio reared at constant temperature. Laboratory-infested bolts produced mostly males, whereas field-collected material produced a 2.7 : 1 male-biased sex ratio. Mean DDs to emergence was 1477.0 +/- 13.4 (males) in laboratory-infested bolts, as well as 1455.2 +/- 11.2 (males) and 1577.8 +/- 19.5 (females) in field-collected material. Field-trapping studies were conducted to compare flight activity with rearing data. Trap captures showed first flight activity and peak catch occurred at 709 and 1145 DDs. The resulting degree-day model predicts early flight activity in early to mid-April for pine stands in southeastern U.S.A., early to mid-May in the Mid-Atlantic region, and late June to early July in the northeast.