FEMALE CALLING BEHAVIOR AND RESPONSE OF MALES TO SYNTHETIC PHEROMONE AND VIRGIN FEMALES IN SPRING AND SUMMER GENERATIONS OF HYPHANTRIA-CUNEA (LEP, ARCTIIDAE) (DRURY) IN NORTHEASTERN CHINA

The Chinese population of Hyphantria cunea (Drury) was investigated re garding female calling, male flight, and male response to synthetic an d natural pheromone. Special attention was given to the little studied spring generation. In the spring, (Ist) generation females called in the beginning of the night, 19:30-01:30, and the older females started calling earlier and calling lasted longer. During the summer, (2nd) g eneration females called in early morning, 03:45-04:50, with a 20 min peak just before sunrise. Pumping rate of the ovipositor ranged betwee n 0.8-1.0 Hz and 1.1-1.2 Hz in spring and summer generation, respectiv ely. Calling longevity of females was 4.7 +/- 0.6 days (mean SEM) in s pring and 3.6 +/- 0.6 days in summer, respectively, and females 2-3 da ys old attracted most males. Synthetic baits (1,3Z,6Z-9,10-epoxyheneic osatriene: 3Z,6Z-9,10-epoxyheneicosadiene: 9Z,12Z,15Z-octadecatrienal, at 1:1:8, total 5-6 mg/dispenser) had the same or higher catch than v irgin females as baits. A bait with 2 mg loading was not competitive, while a 5 mg bait had good activity even when used during both generat ions. Change in dose of synthetics (1-3 x) or number of females (1-6 x ) did not give a clear increase in response, while the coefficient of variation decreased with female number. Smaller sticky traps caught le ss than Uni-traps (covered buckets with DDVp as killing agent), while a large cross-barrier sticky trap caught equal to Uni-trap but proved impractical. Height of trap placement was important in summer generati on, when traps at 4 and 7 m caught 2 x and 4 x more than those at 2 m. The spring generation had a more uniform distribution of catch with h eight. Light intensity and air temperature affected male flight cativi ty, with temperature drop at dusk in Ist gen. and light increase at da wn in 2nd gen., repsectively, judged to be the most important for onse t of male activity.