Management strategies to minimize the use of synthetic chemical acaricides in the control of the cattle tick Rhipicephalus (Boophilus) microplus (Canestrini, 1888) in an area highly favourable for its development in Argentina

Abstract

The aim of this work was to test the efficacy of winter–spring control strategies against Rhipicephalus (Boophilus) microplus (Canestrini, 1888) (Ixodida: Ixodidae) in an area highly favourable for its development in Argentina. Control schemes using three or four annual applications of synthetic acaricides were evaluated. Furthermore, the dynamics of the non‐parasitic phases of R. microplus were analysed to provide a framework for the application of pasture spelling as a tool for tick control. The treatment schemes provided appropriate levels of efficacy against R. microplus and also prevented the occurrence of the major peak in abundance of this tick in autumn. A significant overall effect against R. microplus can be achieved when the control strategies tested in this study are applied within the area most ecologically favourable for this tick in Argentina. Analysis of the dynamics of the non‐parasitic phase of R. microplus indicates that the spelling period required to achieve a significant reduction of larvae in pastures fluctuates between 12 and 17 weeks if spelling is initiated in spring or early summer, but between 20 and 28 weeks if spelling is started in late summer, autumn or winter.

The nonparasitic phase of Dermacentor nitens under field conditions in southeastern Brazil

“…On the other hand, significantly shorter larval survival periods were observed in plots where females were released during (i) late autumn to winter, and (ii) spring to early summer than during other periods. In the first case, the larval survival period was possibly negatively affected by the long period of stress to which overwintering eggs were subjected, as previously reported for R. microplus (Canevari et al, 2017;Nava et al, 2020). In the second case, the short larval survival period was possibly a result of higher mean temperatures, which killed larvae faster by desiccation or starvation; in the latter case, it was assumed that larvae tended to exhaust their energy reserves faster under higher temperatures, as previously reported for R. australis (Wilkinson & Wilson, 1959) and R. microplus (Canevari et al, 2017).…”

“…Larval survival was in most of the times significantly longer in the plots where females were released in March and April (late summer to early autumn). of D. nitens in the state of Minas Gerais (Borges et al, 1999) and for several populations of two other one-host ticks, Rhipicephalus microplus (Canestrini, 1888) in Brazil (Gonzales et al, 1985) and Argentina (Canevari et al, 2017;Nava et al, 2020) and Rhipicephalus australis Fuller, 1899[formerly R. microplus (Estrada-Peña et al, 2012] in Australia (Harley, 1966). On the other hand, significantly shorter larval survival periods were observed in plots where females were released during (i) late autumn to winter, and (ii) spring to early summer than during other periods.…”

One Health Approach to Identify Research Needs on Rhipicephalus microplus Ticks in the Americas

“…Rhipicephalus microplus has only two off-host stages, namely the developing eggs, and the questing larvae, therefore reducing the chances that trends of macroclimate to be the only responsible of an impact on the distribution of R. microplus . There is a substantial body of studies in the Neotropics on the dynamics of both parasitic and non-parasitic phases at different latitudes and how they determine the number of annual generations according to climate and soil use conditions [ 2 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 ]. In subtropical latitudes, it is estimated that a shorter winter would promote an earlier beginning of activity the next spring and, therefore, a variable number of generations, providing that suitable soil/atmospheric water contents are available.…”

“…The determination of the spelling periods required to achieve significant control of R. microplus in different periods of the year at a particular area is the basic knowledge necessary to apply this method. In this sense, there are studies in the Neotropics that already addressed this subject and raised proposals on the adequate application of these methods at different latitudes [ 8 , 19 , 21 , 35 , 36 , 37 ]. Additionally, some models have been developed to infer the impact of different management methods to achieve a maximum mortality of questing larvae in the grass, thus “cleaning” the pasture [ 38 , 39 ].…”

“…In any case, the landscape is affected by the dominant climate and the human actions on the vegetal cover (i.e., the massive deforestation for farming). In this sense, the suitability of areas for the permanent establishment of R. microplus considering both the climatic and soil suitability for the ticks and the availability of grazing cattle have been analyzed and modeled [ 21 , 33 ]. The size and distance among landscape patches and the existence of “preferred” corridors for hosts were demonstrated to influence the density of ticks by comparing a model of the landscape traits with actual questing densities obtained from field surveys of the European tick Ixodes ricinus [ 55 , 56 ].…”