Oviposition, development, and feeding of Scymnus (Neopullus) sinuanodulus (Coleoptera : Coccinellidae): A predator of Adelges tsugae (Homoptera : Adelgidae)

The hemlock woolly adelgid, Adelges tsugae Annand, is a major threat to hem locks in the eastern United States. As part of efforts to control this pest , Scymnus (Neopullus) sinuanodulus Yu et Yao, a potential predator, was col lected from hemlocks in Yunnan, China. Three shipments were imported during 1996 and 1997 to a quarantine laboratory to study the beetle's biology. Be etles began oviposition immediately after transferal from 5 degreesC in the spring, ceased oviposition by June, and laid the same number of eggs. whet her egg laying began in February or in April. Two-year-old beetles laid as many eggs per year as 1 yr-old beetles. We observed only one generation per year. Yearly fecundity averaged 130 eggs with a maximum of 200 per female. Newly emerged beetles remained preovipositional until the following spring , but could be induced to oviposit in the fall by prior exposure to 5 or 10 degreesC for 1.5 mo. The egg, larval (four instars), and pupal stages last ed 10, 20, and 10 d, respectively, at 20 degreesC. From egg to adult took 7 3, 40, and 35 d at 15, 20, and 25 degreesC, respectively. Larval survival w as only 5% at 25 degreesC. Both larvae and adults fed on all stages of A. t sugae, but larvae grew. faster with much higher survival on adelgid eggs, a nd could not complete development on adelgid nymphs alone. When given adelg id eggs, the beetles laid more eggs initially; however, adelgid nymphs seem to satisfy nutritional requirements for oviposition. Laboratory-reared bee tles were similar to field-collected beetles in oviposition, fecundity, fee ding, survival, and development.