The Effect of Resistant Soybean on Male and Female Development and Adult Sex Ratios of Heterodera glycines

Abstract

To determine whether currently used sources of resistance (soybean Plant Introductions [PI] 548402, 88788, 90763, 437654, 209332, 89772, and 548316) influence sex ratios in H. glycines, four inbred lines of the nematode characterized by zero or high numbers of females on resistant soybean were used to observe the number of adult males produced. Nematodes were allowed to infect soybean roots for 5 days in pasteurized sand. Infected plants were washed and transferred to hydroponic culture tubes. Males were collected every 2 to 3 days up to 30 days after infestation (DAI), and females were collected at 30 DAI. Resistance that suppressed adult females also altered adult male numbers. On PI 548402, 90763, and 437654, male numbers were low and close to zero, whereas on PI 88788, male numbers were higher ([alpha] = 0.05). In a separate experiment, the same PIs were infected by an inbred line that tested as an HG Type 0 (i.e., the numbers of females that developed on each PI were less than 10% of the number that developed on the standard susceptible soybean cultivar Lee). In this experiment, male numbers were similar to female numbers on PI 548402, 90763, 437654, and 89772, whereas male numbers on PI 88788, 209332, and 548316 were higher than those of females ([alpha] = 0.05). In all experiments, the total number of adults that developed to maturity relative to the number of second-stage juveniles that initially penetrated the root was less on resistant than on susceptible soybean (P = 0.05), indicating that resistance influenced H. glycines survival and not sexual development.