Note On the Inheritance of Behavior Patterns for Food Selection and Cocoon Spinning in F 1 Hybrids of Callosamia Promethea x c. Angulifera

A study has been made of the food habits and cocoon-spinning behavior of the F1 hybrids of two related species of Atticine moths, Callosamia promethea and C. angulifera. A total of 447 F1 progeny of the cross ♀ C. prornethea X ♂ C. angulifera was used, these having been secured by making use of the fact that cross-assembling between the species can be made to take place. Young larvae at hatching were uniformly indistinguishable phenotypically from first-instar larvae of C. angulifera. They were given the choice as food plants of Syringa vulgaris, Prunus serotina, Sassafras officinale, and Liriodendron tulipifera. The first two are normal food plants for C. promethea, the fourth for C. angulifera. The third is commonly used by both species. Of the 447, 239 chose L. tulipifera, 205 S. officinale, 2 P. serotina, and 1 S. vulgaris. Thus they resembled the male parent in food habits as well as in morphology.... At the time of spinning, the larva of C. promethea typically selects a single leaf and rolls it into a tube, stitching it lightly and also lining it with silk. The larva then leaves the tube and proceeds for some distance up the leaf petiole and the connecting stalk, coating both rather densely with silk. Thereafter it returns to the tube and completes the cocoon, which is thus firmly bound to the parent tree and adheres during the winter. The larva of C. angulifera behaves quite differently. It typically gathers several leaves into a group and fastens them together as a cover for the cocoon. The stalk-sheathing or "stemming" element of the behavior pattern is entirely absent, and the cocoon commonly falls to the ground when the leaves are shed. Unlike the food habit, in cocoon-spinning there was clear evidence that the inheritance of the behavior pattern was polygenic in character. Every grade of behavior was represented between complete stemming of the cocoon and total lack of it, with the majority of the population intermediate. This polygenic basis accords well with the results found for the cocoon-spinning habit in hybrids of Ephestia by CASPARI. Unfortunately both F2 and backcross ova proved uniformly inviable and it was not possible to carry the analysis further. A discussion is presented of a possible significance of this polygenic situation.