MODELS FOR THE DEVELOPMENT AND SURVIVAL OF HYPHANTRIA CUNEA IN RELATION TO TEMPERATURE AND HUMIDITY: INTRODUCTION

Larvae of Hyphantria cunea Drury were reared on early, mid-season, and late foliage collected from the same apple trees. Survival was significantly lower on late foliage and the fecundity of the moths decreased from 604 in the early series to 128 in the late. Half the filial generation was reared under nutritional stress on a deficient synthetic diet and the other half on a very favorable host, speckled alder. Under both conditions there was a strong transmitted influence of parental food quality on the viability of the eggs and on the ability of first-instar larvae to become established on food. The progeny of the late series did not survive beyond this instar. When the filial generation was subjected to nutritional stress, the influence of parental food was apparent throughout the larval, pupal and adult stages, with progeny of the early series having higher survival than those of the mid-season series. However, when the filial generation hail very favorable food, there was no significant difference in survival rates subsequent to the larval establishment period. The quality of foliage available to univoltine populations of H . cunea depends largely on temperature. Thus, in the development of population models for this species, temperature should be treated as a variable having not only direct effects on establishment and survival each season, but also indirect effects on the quality of the progeny in the following season.