Mortality and repellent effects of microbial pathogens on Coptotermes formosanus (Isoptera: Rhinotermitidae)

Maureen S Wright,Mary L Cornelius

doi:10.1186/1471-2180-12-291

Abstract

BackgroundTwo entomopathogenic fungi, Isaria fumosorosea and Metarhizium anisopliae, and one bacterium, Bacillus thuringiensis, were tested for their ability to cause mortality of Formosan subterranean termites (FST), Coptotermes formosanus (Shiraki), after liquid exposure, and for their lack of propensity to repel FST.ResultsThe fungus Isaria fumosorosea at 108 spores/ml caused 72.5% mortality on day 7, significantly higher than the control and 106 spores/ml treatment. On day 14, the 106 and 108 concentrations caused 38.8% and 92.5% mortality, respectively, significantly higher than the control. On day 21, 82.5% and 100% of the termites were killed by the 106 and 108 treatments, respectively. I. fumosorosea did not repel termites at 106 nor 108 spores/g in sand, soil or sawdust. The fungus Metarhizium anisopliae at 108 spores/ml caused 57.5% mortality on day 7, 77.5% mortality on day 14 and 100% mortality on day 21.ConclusionsOn all three days the rate of mortality was significantly higher than that of the control and 106 spores/ml treatment with I. fumosorosea. Neither I. fumosorosea nor M. anisopliae caused repellency of FST in sand, soil or sawdust. The bacterium Bacillus thuringiensis did not cause significant mortality on days 7, 14 or 21. When termites were exposed to cells of B. thuringiensis in sawdust and when termites were exposed to a mixture of spores and cells in sand, a significantly higher number remained in the control tubes. Repellency was not seen with B. thuringiensis spores alone, nor with the above treatments in the other substrates.

Highlights

Two entomopathogenic fungi, Isaria fumosorosea and Metarhizium anisopliae, and one bacterium, Bacillus thuringiensis, were tested for their ability to cause mortality of Formosan subterranean termites (FST), Coptotermes formosanus (Shiraki), after liquid exposure, and for their lack of propensity to repel FST
M. anisopliae was found to repel the Formosan subterranean termite (FST), Coptotermes formosanus, in tree-based mulches, some of the repellency may have been attributable to substances from the mulches [5]
Of the microbes tested, I. fumosorosea demonstrated the highest rate of mortality when termites were exposed to the spores in liquid

Summary

Introduction

Isaria fumosorosea and Metarhizium anisopliae, and one bacterium, Bacillus thuringiensis, were tested for their ability to cause mortality of Formosan subterranean termites (FST), Coptotermes formosanus (Shiraki), after liquid exposure, and for their lack of propensity to repel FST. Results: The fungus Isaria fumosorosea at 108 spores/ml caused 72.5% mortality on day 7, significantly higher than the control and 106 spores/ml treatment. I. fumosorosea did not repel termites at 106 nor 108 spores/g in sand, soil or sawdust. Conclusions: On all three days the rate of mortality was significantly higher than that of the control and 106 spores/ml treatment with I. fumosorosea. When termites were exposed to cells of B. thuringiensis in sawdust and when termites were exposed to a mixture of spores and cells in sand, a significantly higher number remained in the control tubes. A novel strain of M anisopliae was found to cause significantly greater mortality of FST alates and workers than a previously commercialized strain [7]

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Conclusion