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United States Department of Agriculture

Agricultural Research Service

Title: New Strains of the Entomopathogenic Nematode, Steinernema Riobrave: Are They Better for Biological Control of the Citrus Root Weevil, Diaprepes Abbreviatus?

item Stuart, Robin - UNIV. OF FLORIDA
item Shapiro Ilan, David
item Mccoy, Clayton - UNIV. OF FLORIDA

Submitted to: Society for Invertebrate Pathology Annual Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: October 1, 2003
Publication Date: October 1, 2003
Citation: Stuart, R.J., Shapiro Ilan, D.I., Mccoy, C.W. 2003. New strains of the entomopathogenic nematode, steinernema riobrave: are they better for biological control of the citrus root weevil, diaprepes abbreviatus?. Society for Invertebrate Pathology Annual Meeting Proceedings. p.61.

Technical Abstract: The entomopathogenic nematode Steinernema riobrave has proven effective against Diaprepes abbreviatus in certain Florida soils. However, this species is known from only a single strain, and it is possible that other strains of this species might be much more effective. Therefore, we recently returned to the lower Rio Grande Valley in Texas and Mexico where the original strain was isolated and took a series of soil samples in an effort to find new strains. These samples yielded ten new isolates of S. riobrave as well as a new species of entomopathogenic nematode in the genus Heterorhabditis. Laboratory assays comparing the new S. riobrave strains, the old strain, and a mixed strain (formed by pooling all ten new strains) against D. abbreviatus found significant differences in virulence. Under our experimental conditions (24 degrees C, 70 percent RH, Candler sand and 8 percent moisture in 25 dram snap-cap vials and 200 infective juveniles), and after 7 replicates of 20-30 vials per strain per replicate, the old strain produced the lowest average mortality level (57.7 percent) whereas the mixed strain produced the highest average mortality level (84.1 percent). Thus, the best and the worst strains differed by 26.4 percent, with the best strains killing 45.7 percent more than the worst strain. These data indicate that some of the new strains are considerably more virulent than the older strain and justify further testing of the new strains for characteristics important to the biological control of D. abbreviatus in Florida citrus.

Last Modified: 4/22/2015
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