PROJECT SUMMARY

The gypsy moth is the most important defoliating insect of urban and forest hardwood trees in the northeastern United States. Gypsy moth has been in New Hampshire since the early 1900's with population outbreaks occurring at 7-11 year intervals. From its introduction into Massachusetts in the 1860s until the 1940s it was essentially confined to New England, but in recent years gypsy moth has spread throughout the northeastern United States and now has viable populations as far south as Virginia and North Carolina (Anon. 1994). Immediate and temporary control measures using insecticides have long been the major means for preventing defoliation. Proper management depends on treatment within a few days of egg hatch if a foliage protector is to be used (White et al. 1981). Schaub et al. (1995) suggest a window of opportunity for treatment of two weeks or less from the time of initial egg hatch if foliage protection is to be successful. The use of gypsy moth egg hatch models such as that developed by Johnson et al. (1983) has potential to provide the predictive capabilities necessary to plan control procedures in a timely fashion.

Gypsy moth phenology models that provide area-wide predictions using both weather data and topographic features (mesoscale models) can provide valuable information for the timing of pesticide treatments or bioenvironmental controls such as sterile egg mass release (Anon. 1990; Regniere and Bolstad 1994). Such models have been tested in the southeast (Russo et al. 1993 and Schaub et al. 1995) and in Utah (Schaub et al. 1995) with mixed, but promising results. Both of these studies utilized the Johnson et al. (1983) model, or a modification of that model, for estimation of median hatch.

Johnson et al. (1983) included procedures for estimating both the median hatch point using degree-days and the initial hatch point. Subsequent testing of the model have shown that the model estimates initial hatch quite accurately when adjusted for site conditions such as slope and aspect (Johnson, unpublished data).

We plan to develop a mesoscale model to estimate gypsy moth initial hatch for New Hampshire using topography information and weather data during the 1998 season. The model will be tested in at least 10 sites of differing weather and topographic conditions during the 1999 and 2000 gypsy moth hatch seasons, when gypsy moth populations are anticipated to be increasing during the next population cycle (the last peak was in 1992 and 1993).

Data will be processed using existing GIS topographic data and weather data from NOAA reporting sites throughout the state. New Hampshire provides an excellent topography for such a test for two reasons: 1) the model was initially developed from New Hampshire data (one of the problems with the Johnson et al. (1983) model is the need to adjust the date of degree-day accumulation to the local population and climate), and 2) the topographic extremes in New Hampshire are unmatched anywhere in the northeast.

OBJECTIVES

Validate a modified Johnson et al. (1983) model for initial egg mass hatch in ten field sites at various elevations, latitudes and longitudes throughout New Hampshire, using 100 selected egg masses per site.

Test the impact of host tree species, aspect, height above ground and egg mass location (on bark and under bark flaps) on initial hatch and duration of hatch in the ten field sites chosen in Objective 1 using the 100 selected egg masses.

Incorporate the modified Johnson et al. (1983) model into a framework of mesoscale weather data using latitude, longitude and elevation to estimate daily maxima and minima from NOAA weather stations throughout New Hampshire.

Validate the mesoscale model using the ten field sites chosen in Objective 1 by monitoring the observed initial hatch and duration of hatch for 100 selected egg masses at each site.

REFERENCES

Anonymous. 1990. Gypsy moth research and development program. USDA-FS Northeast Forest Expt. Stn., October 1990. 29 pp.

Anonymous. 1994. Gypsy moth survey 1994. [Map] Arkansas Cooperative Extension Service, Cooperative Agricultural Pest Survey.

Johnson, P. C., D. P. Mason, S. L. Radke & K. T. Tracewski. 1983. Gypsy moth, Lymantria dispar (L.) (Lepidoptera: Lymantriidae), egg eclosion: degree-day accumulation. Environ. Entomol. 12(3): 929-932.

Regniere, J. & P. Bolstad. 1994. Statistical simulation of daily air temperature patterns in eastern North America to forecast seasonal events in insect pest management. Environ. Entomol. 23(6): 1368-1380.

Russo, J. M.; Liebhold, A. M. & Kelley, J. G. W. 1993. Mesoscale weather data as input to a gypsy moth (Lepidoptera: Lymantriidae) phenology model. J. Econ. Entomol. 86(3): 838-844.

Schaub, L. P., F. W. Ravlin, D. R. Gray & J. A. Logan. 1995. Landscape framework to predict phenological events for gypsy moth (Lepidoptera, Lymantriidae) management programs. Environ. Entomol. 24(1): 10-18.

White, W. B.; MacLane, W. H. & N. F. Schneeberger. 1981. Pesticides, pp. 423-444. In C. C. Doane and M. L. McManus [eds.], The gypsy moth: research toward integrated pest management. U. S. Dep. Agric. For. Serv. Sci. Ed. Admin. Tech. Bull. 1584.