Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: February 20, 2010
Publication Date: N/A
Technical Abstract: Heterodera glycines collected from fields in Maryland exhibited very low hatch and reproduction rates in the laboratory. When such eggs were used to establish a laboratory culture on Glycine max, low reproductive rates continued for 2 generations. However, after 2 generations, the field egg derived cultures showed a dramatic increase in both hatch (e.g. 45-70 %) and reproduction rates, approaching those of long established laboratory cultures. Regardless of the source of H. glycines and the rate of hatch, however, all qualitative aspects of hatching behavior were similar. In separate experiments, we found that hatching of infective juveniles from Heterodera glycines eggs, exposed to low temperature (50C) in vitro, was significantly reduced even after return of the eggs to normal rearing temperature. J2 hatch from eggs exposed to 50C for 7 days, when measured at 12 days after returning treated eggs to a 270C, was reduced 40% relative to the control (non-chilled) group. There was a direct, but not linear, relationship between length of low temperature treatment and hatch suppression. Hatch from eggs treated for 4 weeks was 70% of that for controls. Remarkably, the characteristic shape of the H. glycines hatch curve was unchanged regardless of treatment, and in all cases, the most rapid hatch occurred between 2 and 10 days of setting up the hatch assay. The durability of hatching behavior of H. glycines obtained from various sources and exposed to varied conditions, and implications of this behavior for investigating control strategies, are discussed.