Delay differential systems for tick population dynamics.

Ticks play a critical role as vectors in the transmission and spread of Lyme disease, an emerging infectious disease which can cause severe illness in humans or animals. To understand the transmission dynamics of Lyme disease and other tick-borne diseases, it is necessary to investigate the population dynamics of ticks. Here, we formulate a system of delay differential equations which models the stage structure of the tick population. Temperature can alter the length of time delays in each developmental stage, and so the time delays can vary geographically (and seasonally which we do not consider). We define the basic reproduction number [Formula: see text] of stage structured tick populations. The tick population is uniformly persistent if [Formula: see text] and dies out if [Formula: see text]. We present sufficient conditions under which the unique positive equilibrium point is globally asymptotically stable. In general, the positive equilibrium can be unstable and the system show oscillatory behavior. These oscillations are primarily due to negative feedback within the tick system, but can be enhanced by the time delays of the different developmental stages.

Development of acaricide resistance in tick populations of cattle: A systematic review and meta-analysis.

The development of acaricide resistance in ticks infesting cattle is a major problem in the livestock industry in tropical and subtropical regions worldwide. To determine the current global trends and prevalence of acaricide resistance development (ARD) in tick populations of cattle, a systematic review and meta-analysis with an emphasis on Rhipicephalus (Boophilus) microplus was conducted. Data searches from five English electronic databases yielded 88 journal articles published between 1992 and 2020. In total, 218 in - vitro bioassays were used to investigate 3939 tick populations of cattle; of these, the 57.6% that exhibited ARD were largely limited to South America (Brazil), Central America (Mexico), and Asia (India). A total of 3391 of these tick populations were R. (B.) microplus, of which 2013 exhibited ARD. Random effects meta-analyses indicated that the exhibition of ARD was higher in R. (B.) microplus (66.2%) than in other tick species. Global prevalence estimates of ARD in R. (B.) microplus vary as a function of geography, detection methods, and acaricide compounds. In general, high heterogeneity was noted among the studies. However, homogeneity was observed among studies from India, suggesting the establishment of acaricide resistance in Indian R. (B.) microplus populations. Current tick control interventions are urgently required to limit the evolution and implications of resistance development.