Some Maternal Influences on Progeny Quality in the Western Tent Caterpillar, Malacosoma pluviale (Dyar)

Abstract

The different types of individuals among the progeny of the western tent caterpillar, Malacosoma pluviale (Dyar), are concentrated in different parts of the egg mass. The most agile progeny come from some of the first eggs laid, and the least viable are among the last deposited. There is evidence that this serial arrangement stems from unequal partitioning of the maternal food reserves during egg production: a relationship similar to that recently demonstrated in the spruce budworm by I. M. Campbell. In M. pluviale, however, there also is evidence that the differences in feeding rate and food capacity displayed by the different types of females during their own larval stage affect the proportions of the various types of progeny per egg mass as well as the viability of consecutive groups of eggs within the mass. Although these maternal influences are not heritable in the usual genetic sense, they are clearly transmissible between generations. And field studies have shown that their more adverse consequences for local populations are cumulative and ultimately lethal.