The 2005 ESA Annual Meeting and Exhibition
December 15-18, 2005
Ft. Lauderdale, FL

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Friday, December 16, 2005
D0127

Biological and strategical importance of timing and density of egg releases of Sasajiscymnus (=Pseudoscymnus) tsugae against the hemlock woolly adelgid, Adelges tsugae, in the Great Smoky Mountains National Park

Isaac Deal, ideal@utk.edu1, Jerome F. Grant, jgrant@utk.edu1, James R. "Rusty" Rhea, rrhea@fs.fed.us2, Paris L. Lambdin, plambdin@utk.edu1, and Daniel Palmer3. (1) University of Tennessee, Department of Entomology and Plant Pathology, Knoxville, TN, (2) USDA Forest Service, Forest Health Protection, 200 WT Weaver Blvd, Asheville, NC, (3) New Jersey Department of Agriculture, Division of Plant Industry, West Trenton, NJ

The hemlock woolly adelgid, Adelges tsugae, is an invasive alien pest that currently threatens native hemlock species in the eastern US. Of particular concern is the burgeoning infestation of hemlock woolly adelgid on hemlocks in the Great Smoky Mountains National Park (GRSM). Sasajiscymnus (=Pseudoscymnus) tsugae, a small lady beetle from Japan, is being reared and released as a biological control agent for this intruder. Unfortunately, rearing facilities are unable to produce adult beetles in sufficient quantity to meet demand. Alternate release strategies, such as egg releases, are under investigation as a way to increase the availability of the predators. Successful release of beetles as eggs, rather than adults, would allow rearing facilities to increase their beetle production by several fold. This study assesses the feasibility of releasing S. tsugae eggs in the field. Eggs of S. tsugae were placed in sleeve cages that encased infested branches of hemlock trees in the GRSM. Eggs (n=100) were placed on twigs in sleeve cages in February, March, and April to determine the optimum time of year to release eggs. Sleeve cages with varying densities of eggs were evaluated throughout the field season to determine the most effective egg density for releases. Survivability and development of S. tsugae throughout the field season will be discussed. Our data suggest that egg releases are a viable option for increasing the availability of S. tsugae, while reducing the labor and cost of rearing the beetles.


Species 1: Hemiptera Adelgidae Adelges tsugae (hemlock woolly adelgid)
Species 2: Coleoptera Coccinellidae Sasajiscymnus tsugae
Keywords: Invasive species, Biological control