Figure 1.
Diagram of Life Cycle of the Blacklegged Tick (I. scapularis)
Shows the four life stages, egg, larva, nymph, adult, and the times during the life cycle that both abiotic (GDD, PPT), and biotic (acorns and various hosts) factors might exert influence. Year t is the year during which nymphal ticks seek hosts, including humans, and represents the focal year with respect to risk of exposure.
Table 1.
Model Comparison Statistics for Independent Variables Potentially Influencing the DON Based on the Full Dataset (58 Plot Years)
Table 2.
Model Comparison Statistics for Independent Variables Potentially Influencing the DON Based on the Subset of Plot Years for Which All Independent Variables Were Estimated (42 Plot Years)
Figure 2.
Effects of Population Density of Eastern Chipmunks (T. striatus) on DON
Shows relationship between number of chipmunks per 2.25-ha grid in year t−1 and DON (number per 100 m2) in year t. This regression model for DON had the most support.
Figure 3.
Effects of Acorn ( Quercus spp.) Density on NIP
Shows effects of acorns per square meter in year t−2 on NIP (percentage of nymphs infected with B. burgdorferi) in year t. This regression model for NIP had the most support.
Table 3.
Model Comparison Statistics for Independent Variables Potentially Influencing NIP Based on the Full Dataset (58 Plot Years)
Table 4.
Model Comparison Statistics for Independent Variables Potentially Influencing NIP Based on the Subset of Plot-Years for Which All Independent Variables Were Estimated (42 Plot Years)
Table 5.
Model Comparison Statistics for Independent Variables Potentially Influencing the DIN Based on the Full Dataset (58 Plot Years)
Table 6.
Model Comparison Statistics for Independent Variables Potentially Influencing the DIN Based on the Subset of Plot Years for Which All Independent Variables Were Estimated (42 Plot Years)
Figure 4.
Effects of Acorn and Rodent Densities on DIN
(A) Effects of the product of acorn density (acorns per square meter) in year t−2 and mouse (P. leucopus) density (number per 2.25-ha grid) in year t−1 on the density of B. burgdorferi-infected nymphs (number per 100 m2) in year t. This regression model for DIN had the most support.
(B) Effects of the product of acorn density (acorns per square meter) in year t−2 and chipmunk (T. striatus) density (number per 2.25-ha grid) in year t−1 on the density of B. burgdorferi-infected nymphs (number per 100 m2) in year t. This regression model for DIN had nearly as much support (AICcorr) as the mouse model (A) and a higher r2 value.
Figure 5.
Effects of Acorn Density on Mouse and Chipmunk Densities
Shows effects of acorn density (acorns per square meter) in year t−2 on (A) mouse (P. leucopus) density (number per 2.25-ha grid) in year t−1 and (B) chipmunk (T. striatus) density (number per 2.25-ha grid) in year t−1. (C) Correlation between mouse density and chipmunk density across plots and years.
Figure 6.
Time Series of Acorn, Tick, and Chipmunk Densities on Study Plots
Shows time series of acorn density (acorns per square meter), chipmunk density (number per 2.25-ha grid), and DON (number per 100 m2) on the two longest-established study plots, Henry Farm (A) and Teahouse (B). Note that, typically, chipmunk density tracks acorn density with a 1-y lag, and DON tracks chipmunk density also with a 1-y lag.