Acorn crops can predict increases in Lyme-carrying ticks two years later

A long-running study of Lyme disease ecology found that especially large acorn crops can predict an increase in nymphal ticks two years later. The findings, published in Proceedings of the National Academy of Sciences, draw on more than 35 years of research tracking ticks, animals, oak trees and weather.

The researchers found that acorn abundance can help forecast mouse populations, which tend to grow after a large crop. Years with especially large mouse populations were followed by approximately 40% more nymphal ticks the next year. At the study site in Dutchess County, New York, deer numbers had no statistically significant connection with nymphal tick abundance. The researchers said mouse abundance predicted tick numbers, but did not consistently predict what percentage of ticks carried Lyme disease bacteria.