Development of the gypsy moth (Lepidoptera: Lymantriidae) on Garry oak and red alder in western North America

The suitability of Garry oak (Quercus garryana) and red alder (Alnus rubra)as hosts for the gypsy moth. Lyrnantria dispar (L.), was assessed under laboratory conditionsby observing larval survival, larval weights, foliage consumption, developmental period,pupal weight. and ova production. Survival was not significantly different between larvaefed Garry oak (98.75) or red alder (97.4%). The mean maximum live larval weights weresignificantly different between sexes but not between diets. Females weighed 2,498 mg whenfed Garry oak and 2,210 mg when fed red alder. Males weighed 894 mg when fed Garryoak and 737 mg when fed red alder. The mean amount of foliage consumed was significantlydifferent between sexes but not diet. Female larvae consumed an average of 705 cm= ofGarry oak and 678 cm= of red alder foliage. Male larvae consumed 247 crn: of Garry oakand 253 cm: of red alder foliage. The mean time from egg hatch to pupation was significantlydifferent between sexes and diets. Female larvae pupated in 39.5 d on Garry oak and 48.1d on red alder. Male larvae pupated in 33.4 d on Garry oak and 40.6 d on red alder. Pupalweights were not significantly different between sexes or diets. Male pupae weighed 554 mgfrom a larval diet of Garry oak and 572 mg from red alder. Female pupae weighed 1,846mg from Garry oak and 1.711 mg from red alder. An average of 863 ova (Garry oak) versus758 ova (red alder) was present in the reproductive tract of 2-ch-ald females, an insignificantdifference. Pupal weights, frass production, and ova production were highly correlated.Nutritional indices indicated that Garry oak foliage was converted into biomass slightly moreefficiently than that of red alder. These data indicated that foliage of either Carry oak orred alder provided a very suitable diet for the gypsy moth.
KEY WORDS Insecta. host suitability, Lymantria dispar, hardwoods