A STRAIN OF THE FUNGUS METARHIZIUM ANISOPLIAE FOR CONTROLLING SUBTERRANEAN TERMITES

摘要

Alates of the Formosan subterranean termite (FST)1 Coptotermes formosan?s Shiraki, collected after swarming in 2002 died within 48 hrs, and the cadavers were visibly infected with a fungus. Fungi were picked from the cadavers, transferred to media and ultimately isolated to purity. The individual fungal cultures were then used to infect FST workers. A single fungal isolate, C4-B, taxonomically identified as Metarhizium anisopliaß (Metschnikoff), was found to cause rapid mortality of FST alates. This is the first report of a biological control agent for termite alates. In initial experiments C4-B was more lethal to both alates and workers when compared to M. anisopliae strain ESC1, previously marketed as the termite biocontrol agent BioBlast®. Dose response assays in which FST alates were exposed to a known concentration of C4-B spores revealed that 106 spores/µl killed 100% of the alates in 3 days; both 105 and 104 spores/µl required 6 days, 103 spores/µl, 9 days, and 10° spores/µl, 12 days. Assays with workers demonstrated that 106 and 105 spores/µl killed 100% of the workers in 6 days. In an experiment to test the transfer of inoculum from infected workers to uninfected nestmates, 62.8% of the workers died in 21 days when only 20% of the workers had been inoculated. Mortality of alates caused by C4-B was tested at two field sites by dispersing fungal spores on grassy lawns and collecting alates from the treated areas. Alates thus infected showed 100% mortality by day 5, while only 64.8% untreated control alates from the same collection area were dead on that day.