Laricobius nigrinus (Fender) (Coleoptera: Derodontidae), has been approved for field release as a biological control agent against hemlock woolly adelgid, Adelges tsugae, Annand (Homoptera: Adelgidae), a lethal pest of eastern hemlock trees. A univoltine species found in the Pacific Northwest, L. nigrinus has a complex life cycle involving soil pupation and adult summer aestivation. Current rearing of this predator is constrained by high mortality and a lack of knowledge of which life stages incur significant mortality. Our objective is to streamline rearing procedures by identifying life stages with high developmental mortality and determining factors critical to the success of each life stage. A new rearing cage has been devised that enables the quantification of larvae reaching maturity and an estimate of pupal and aestivational success. Factors under investigation are ovipositional period, larval density, soil type, moisture level and disturbance during pupation and aestivation. Preliminary results show that egg laying can be optimized by limiting the number of days that adults can oviposit on individual branches. Egg and larval stages suffer 25% mortality overall when given sufficient food. Between February and June 2001, a total of 7000 larvae were successfully reared to maturity from an initial 350 adults. On average, L. nigrinus suffers 30% mortality during pupation at the moisture levels tested and there is no difference in aestivational success when adults are stored in the various soil types investigated. Moisture level and disturbance of the soil may contribute to mortality of adults during summer aestivation, and will be assessed by adult emergence in the fall 2001. Success in this project will expedite the mass release of L. nigrinus in the field as part of a predator complex intended to control hemlock woolly adelgid populations.
Species 1: Coleoptera Derodontidae Laricobius nigrinus
Species 2: Homoptera Adelgidae Adelges tsugae (hemlock woolly adelgid)
Keywords: Rearing Derodontidae, Adelgid Predator
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA