Acorns Tied To Disease

Acorns, one of the innocuous signs of fall, could be harbingers of an outbreak of Lyme disease.

Clive G. Jones of the Institute of Ecosystem Studies in Millbrook, N.Y., studied three patches of forest in upstate New York over a three-year period to determine the relationship among acorns, mice, ticks, deer and gypsy moths.

When the researchers spread nearly four tons of acorns on their experimental plots, the number of white-footed mice skyrocketed.

The researchers also found a sharp increase in larvae of black-legged ticks, apparently because the acorns attracted tick-bearing deer.

Mice carry the Lyme disease-causing organism that ticks spread to people. Under natural conditions, mice tend to multiply every two to five years, when the number of acorns rises.

A bumper crop of acorns could signal an increased risk for Lyme disease, which can be disabling.

But the researchers found that when they reduced the mouse population, the number of young gypsy moths soared, apparently because mice eat immature gypsy moths and their eggs.

So suppressing acorn production to cut the mouse population could send gypsy moth numbers soaring, threatening trees.