NEON ticks, 2014–2024: site density trends did not follow site temperature, lone star ticks stayed absent at five northern sites, and dog ticks but not blacklegged ticks followed prior-year rodents

Question: Can an independent analysis reproduce NEON tick density trends for 2014-2024, are site trends more positive at cooler sites as range expansion predicts, and does a rodent-fed tick follow the NEON rodent index? Data: NEON tick drag and flag data (DP1.10093.001, RELEASE-2026, via neonDivData), 13,965 events on 310 plots at 46 sites, and NEON small-mammal data. Method: We gave unidentified nymphs and adults to species in proportion to identified ticks. For 43 site x species x stage units, we fitted negative binomial models with plot, method, season and a linear year term, with a year-resampling bootstrap. We pooled site trends with a random-effects model and used site mean annual temperature (MAT) as a moderator. Results: (A) Reproduction. Pooled trends agree with SCI 0c852071 within 1 percentage point per year: Amblyomma americanum nymphs -4.3% per year (95% CI -14.2 to +6.8), Ixodes scapularis nymphs +3.3% (-9.3 to +17.6), Dermacentor variabilis adults +4.6% (-7.3 to +18.0). Site trends of 39 shared units correlate with r = 0.965, and 35 of 39 have the same significance class. (B) New tests. Site trends do not change with MAT for any of five species-stage units (all p >= 0.14; all units -0.4% per year per degree C, -1.8 to +1.0). A. americanum did not occur in 1,797 events at five northern sites (42-46 N) in 11 years. It occurred for the first time at two western sites (OAES 2018, CLBJ 2021). In an exploratory lag test with year effects removed, D. variabilis adults followed the rodent index of the previous year (slope +0.50, +0.27 to +0.79; 12 sites), but I. scapularis nymphs did not follow the Peromyscus index (-0.14, -0.55 to +0.09; 8 sites), which agrees with SCI 588f5817. Thus the rodent index has a signal. Allocation of unidentified ticks changes trends very little (r = 0.99). Limitations: There are only 10-11 years and 5-12 sites per unit, so small uniform changes and moderate temperature effects are not excluded. The 2019 change in the counting protocol can bias trends. The lag test was not in our plan. Tick plots and mammal grids are at different places.

ticks · Amblyomma americanum · Ixodes scapularis · Dermacentor variabilis · Haemaphysalis longicornis · NEON · population trends · range expansion · reproduction · vector-borne disease · meta-regression · Peromyscus · host lag