Disease-Carrying Ticks in for Trouble

It's unclear how this El Niño winter will affect 1998 tick populations. But chemist Patricia Allen of USDA's Agricultural Research Service is ready and waiting nonetheless.

Since early 1997, she's been exposing black-legged deer ticks to spores of naturally occurring fungi at ARS' Parasite Biology and Epidemiology Laboratory in Beltsville, Maryland. Of the half- dozen fungi she has tested under controlled lab conditions, Metarhizium anisopliae proved the most lethal to the ticks, especially against juvenile forms.

Now she's hoping to show that the fungus will also kill ticks under natural conditions. Of special interest is the impact on tick eggs and emerging larvae. To that end, she'll begin a first round of outdoor tests in late April on small-scale plots at Beltsville. She'll spray a commercial preparation of M. anisopliae developed by Ecoscience Corp. of East Brunswick, New Jersey.

Allen's research is part of a project to explore the potential and safety of using beneficial fungi and nematodes as non-chemical tick controls. Her approach targets black-legged deer ticks because the pests spread the bacterium responsible for Lyme disease in humans. In 1996, the federal Centers for Disease Control and Prevention in Atlanta, Ga., received more than 16,000 reports of Lyme disease.

With this winter's wet, mild weather, Allen and ARS colleague John Carroll report little trouble collecting enough ticks for their studies at the Beltsville lab. Carroll, an entomologist, coordinates Maryland's participation in the ARS-led Northeast Regional Tick Control Project. This multi-state project uses special feeding bins to lure deer into being coated with a chemical called amitraz. The chemical kills adult ticks feeding on the deer without harming the animals.

A more detailed story on the scientists' work appears in the March issue of Agricultural Research, on the World Wide Web at:

http://www.ars.usda.gov/is/AR/archive/mar98/tick0398.htm

Scientific contact: Pat Allen, Parasite Biology and Epidemiology Laboratory, Beltsville, Md., Phone (301) 504-8772, fax (301) 504-5306, pallen@ggpl.arsusda.gov.