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

Abstract

Abstract 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.