A redução da produção de leite em bovinos é um dos aspectos majoritários na composição total do valor de impacto econômico provocado por R. (B.) microplus. Portanto, o objetivo deste estudo foi estimar a perda decorrente da carga parasitária, observada em uma propriedade produtora de leite na região central de Minas Gerais. Para tal, foram consideradas 30 contagens de carrapatos, distribuídas de maneira uniforme durante o período de um ano, em um rebanho bovino com 74 vacas de composição racial 3/4 Holandês x Zebu, mantidas sob sistema de produção intensivo em pastoreio. A partir dos dados observados, foi possível estimar que 937.968 teleóginas completaram o repasto sanguíneo e foram responsáveis pela redução de 6.678 litros de leite durante o período avaliado. Esse valor corresponde a uma redução de 2,7% da produção, média de 90,24 litros por vaca em lactação

Rhipicephalus (Boophilus) microplus is the main ectoparasite affecting livestock worldwide. For a successful parasitism, ticks need to evade several immune responses of their hosts, including the activation of the complement system. In spite of the importance of R. microplus, previous work only identified one salivary molecule that blocks the complement system. The current study describes complement inhibitory activities induced by R. microplus salivary components and mechanisms elicited by putative salivary proteins on both classical and alternative complement pathways. We found that R. microplus saliva from fully- and partially engorged females was able to inhibit both pathways. Saliva acts strongly at the initial steps of both complement activation pathways. In the classical pathway, the saliva blocked C4 cleavage, and hence, deposition of C4b on the activation surface, suggesting that the inhibition occurs at some point between C1q and C4. In the alternative pathway, saliva acts by binding to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and reducing C3b production and deposition as well as cleavage of factor B. Saliva has no effect on formation or decay of the C6 to C8 components of the membrane attack complex. The saliva of R. microplus is able to inhibit the early steps of classical and alternative pathways of the complement system. Saliva acts by blocking C4 cleavage and deposition of C4b on the classical pathway activation surface and, in the alternative pathway, saliva bind to initial components of the cascade (C3b and properdin) thereby preventing the C3 convertase formation and the production and deposition of additional C3b.

Bovines are suitable hosts and can be affected by fly infestations. Flies pose a significant threat to cattle livestock in Latin America (LA), causing substantial economic repercussions to animal production (reduced productivity, veterinary expenses, and decreased animal welfare) and damage to human health. The most important flies affecting cattle in Argentina, Brazil, Colombia, Mexico, and Uruguay are Haematobia irritans, Dermatobia hominis, and Cochliomyia hominivorax. Due to production losses and the consequent economic costs associated with these flies, control measures must be implemented, primarily relying on insecticidal products. However, decision-making for preventing and treating animals with insecticides varies due to differences in environmental conditions across countries and regions, production systems, animal populations, infestation levels, animal welfare, and the prevalence of myiasis, among other factors. Although insecticides remain the most effective option for fly control in cattle, resistant populations have developed, rendering them less effective. To overcome fly resistance to insecticides, non-chemical (mechanical, environmental, biological, and genetic) methods are being integrated into alternative control and eradication strategies. The use of integrated livestock fly control contributes to safeguarding animal, public, and environmental health. This review is designed to support individuals and institutions, both civil and governmental, addressing the ongoing challenge posed by flies affecting livestock.

The present study reports a case of conspecific hyperparasitism for Amblyomma sculptum. Two partially engorged females were collected from two naturally infested dairy cows and placed in a single petri dish to be transported to the laboratory, where they were held in a biological oxygen demand (BOD) incubator chamber under controlled conditions of 27 ± 1 °C and 85 ± 5% RH. After one day, it was observed that the smaller female (female 1) was attached to the dorsal surface of the larger female (female 2). The hypostome and chelicerae of the female 1 were entirely inserted into the cuticle of the female 2, characterizing tick attachment. Pictures were taken to illustrate the finding. After a few hours, the female 1 detached spontaneously and showed no visible signs of additional enlargement (engorgement). The females did not lay eggs and the survival period was not recorded. To our knowledge this is the first report of hyperparasitism for A. sculptum and the fourth for the genus Amblyomma.

Acaricide resistance is a major challenge for the control of Rhipicephalus microplus, and differences between laboratory and field efficacy may complicate the assessment of resistance. However, the influence of parasitic developmental stages on acaricide susceptibility remains poorly understood. Metanymphs were historically considered an acaricide-resistant stage, although this assumption was later questioned. To re-evaluate this issue, three experiments were conducted. First, replicated field spray treatments were performed to evaluate mortality over time. Second, feeding chambers attached to cattle were used to expose ticks at different stages to acaricide. Third, partially engorged females were sprayed and surviving engorged females were evaluated for reproductive performance. Field mortality varied according to the developmental stages corresponding to each assessment day. In feeding chambers, mortality reached 83% in non-engorged nymphs and 90% in young adults, compared with 29% in engorged nymphs and 8% in controls. Females surviving treatment while partially engorged maintained high reproductive performance, whereas subsequent acaricide immersion markedly reduced hatchability and egg production. These findings demonstrate stage-dependent differences in acaricide susceptibility and indicate that developmental and engorgement status may contribute to discrepancies between laboratory and field efficacy tests.