The Factors of Inheritance and Parentage as Affecting the Ratio of Alate to Apterous Individuals in Aphids

Abstract

THE influence of parentage on aphid forms has been noted by Shull (191-8), is very apparent from the earlier results obtained by Gregory (1917) and has been recently confirmed by Wadley (1923). The results of all three of these workers appear to be entirely in accord in two respects, i.e., in regard to the existence of a tendency for winged parents to produce wingless offspring and for wingless parents to produce winged offspring. Shull also noted that winged males were the progeny of apterous mothers and that wingless oviparous females were the offspring of alate females. These observations caused him to relate the phenomena with Riddle's theory of sex. He regarded the winged agamic individuals and the males as the forms of high metabolism and low energy content and the wingless agamie females and the oviparous females as forms of low metabolism and high energy content. AMiss Gregory (Gregory, 1917), whose results were published a year earlier than those of Shull, came to the conelusion that the primary factor in determining the development of wings was the food supply. Her work was done with the green pea-aphid iicrosiphuitn destructor. In one of experiments, G series (Gregory, 1917, p. 302, table IV), it was found that winged parents even when starved produced no winged offspring. Wadley observed the effects of various factors on progeny of different parentage and grandparentage. His