Effect of Infection Density On Sex Ratio of Heterodera Glycines 1)

Abstract

Approximately equal numbers of males and females of Heterodera glycines Ichinohe developed in roots of soybean seedlings at low infection densities. High infection densities significantly increased the male to female ratio, first in the secondary and tertiary roots and then in the primary root. Infection density of secondary roots influenced nematode sex ratio in tertiary roots. Increased male to female ratios were attributed to differential death-rate of male and female larvae under conditions of food stress created by crowding.