Submitted to: Comparative Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 1, 2007
Publication Date: January 31, 2008
Citation: Masler, E.P., Zasada, I.A., Sardanelli, S. 2008. Hatching behavior in Heterodera glycines in response to low temperature. Comparative Parasitology. 75(1):76-81. Interpretive Summary: Plant-parasitic nematodes attack all crops of agricultural importance, causing over $10 billion in losses annually to U.S. farmers. One problem facing growers is that environmental concerns will result in the elimination of the most extensively used chemical nematicide from the United States within the next few years. This loss makes the discovery of environmentally and economically sound replacement control agents critical. One approach to discovering new ways to control nematodes is to develop new experimental systems for identifying natural and nematode-specific biochemicals. Such biochemicals can then be targets for new control agents. We have developed a laboratory system for producing plant-parasitic nematodes that do not hatch normally and can now use these altered nematodes for biochemical comparisons with normal animals and discovery of molecules that control hatch. Consequently, this information will be used by researchers in the agrochemical and agricultural biotechnology industries who are developing safe, selective methods for nematode control.
Technical Abstract: Heterodera glycines eggs were exposed to low temperature (5°C) in the dark for various periods, and the effects of these treatments on hatching at 27°C were assessed. Low temperature treatments caused a significant decrease in total percent egg hatch relative to untreated controls, but did not affect either the timing of egg hatch or the qualitative aspects of the hatch curve. Hatch curves comprised three distinct phases: hatch initiation, linear increase, and hatch rate decline. Hatch rates for all treatments were greatest during the first 12 days following hatch assay initiation, and rate decline occurred by day 14 regardless of treatment. Egg viability tests demonstrated that treatments did not affect mortality and treatment effects did not affect progeny. Total percent hatch was directly dependent upon second phase linear increase rate. Depression of hatch by low temperature was not reversed when eggs were returned to 27°C. Results suggest that one or more developmental events were arrested, and that a diapause was induced.