Population dynamics of the tick Rhipicephalus microplus in cattle under three grazing systems in the mexican humid tropics

Resumen

Objective: (1) To determine the population dynamics of R. microplus ticks in cattle under three grazing systems in the humid tropics; (2) to compare the effect of the grazing system on R. microplus infestations in cattle; and (3) to correlate R. microplus infestations in each treatment with environmental variables.

Methodology: The experiment was conducted from April 2023 to March 2024 in Tlapacoyan, Veracruz, Mexico. Thirty heifers (3/4 Brahman × 1/4 Holstein), aged 4–7 months, were used and allocated to three experimental groups (n = 10; grazing systems). The animals in groups 1 and 2 were managed under rotational grazing with 30 (SP30) and 45 days of rest (SP45), respectively, whereas those in group 3 were kept under a continuous grazing system (no rest) (SP00). Tick counts on the animals were performed every 14 days. Daily measurements of ambient temperature (TA), precipitation (PP), and relative humidity (RH) were recorded.

Results: During the evaluation year, five peaks in R. microplus population dynamics were observed in the calves of groups SP30 and SP00, whereas only two peaks were recorded in the SP45 group. The tick population peaks in all three groups occurred mainly during the dry and rainy seasons. Animals in the SP45 group had the lowest infestation rates of R. microplus throughout the year (P < 0.0001). In contrast, animals in the SP30 group showed the highest infestations (P < 0.0001).

Conclusions: Grazing management and pasture rest periods in the humid tropics influence the population dynamics of R. microplus in cattle