Therapeutic and persistent efficacy of doramectin against Boophilus microplus in cattle

Effect of a spray formulation on the reproductive parameters of a susceptible population of Rhipicephalus (Boophilus) microplus

“…Pereira (2009) evaluated the effects of ivermectin, abamectin and doramectin, all administered subcutaneously at a dosage of 200 mcg/kg, on the average and the reduction in oviposition among engorged females collected from experimentally infested animals that were kept in fields. More recently, Lopes et al (2013) evaluated the effect of ivermectin, Lopes et al (2013), regarding the reduction in oviposition among female ticks exposed to this formulation (62.17%), were slightly inferior to those obtained by Gonzales et al (1993) (99.9%), George & Davey (2004) (91.43%) and Pereira (2009) (83.51%), all of whom used doramectin administered as a pour-on (500 mcg/ kg) or subcutaneously (200 mcg/kg), respectively. For abamectin administered subcutaneously (200 mcg/kg), Pereira (2009) found that this formulation provided a percentage reduction of 37.11% in the oviposition among engorged females exposed to this active agent.…”

“…The first studies evaluating the reproductive parameters of female fully engorged ticks, detached from experimentally infested animals that had been treated with macrocyclic lactones, were conducted by Gonzales et al (1993) and George & Davey (2004), using doramectin administered as a pour-on (500 mcg/kg) and subcutaneously (200 mcg/kg). Pereira (2009) evaluated the effects of ivermectin, abamectin and doramectin, all administered subcutaneously at a dosage of 200 mcg/kg, on the average and the reduction in oviposition among engorged females collected from experimentally infested animals that were kept in fields.…”

“…Subsequently, the egg mass of each group and post-treatment day was transferred to adapted 3-mL syringes and was returned to the BOD incubator at 27 °C and approximately 85% relative humidity to stimulate larval hatching. After 20 days of larval hatching in the BOD incubator, the percentage hatchability was calculated in accordance with the methodology described by Gonzales et al (1993). The percentage hatchability of each sample group (derived from the daily sample of detached preselected engorged female ticks) was visually estimated using a stereomicroscope with an ocular grid, by comparing the proportion of larvae in relation to the proportion of unhatched eggs for each group and post-treatment day (DRUMMOND et al, 1973;GONZALES et al, 1993;GEORGE & DAVEY, 2004;HOLDSWORTH et al, 2006).…”

“…) microplus, it is necessary to remember that only 5% of the parasites are located in the host, meaning that the remaining 95% stay in the environment. Based on this idea, several studies (GONZALES et al, 1993;GEORGE & DAVEY, 2004;PEREIRA, 2009;LOPES et al, 2013) have emphasized that successful control over a tick population on a given farm is related not only to great efficacy of a certain acaricide, but also to the deleterious effects that these active agents have on tick populations in the field, especially in relation to the reproductive parameters of engorged R. (B.)…”

Effects of different spray formulations on the reproductive parameters of engorged Rhipicephalus (Boophilus) microplus females detached from experimentally infested cattle

“…microplus, it is necessary to consider that only 5% of the ticks are located on the host, with the remaining 95% remain in the environment. Accordingly, several studies (Gonzales et al, 1993;George and Davey, 2004;Pereira, 2009;Lopes et al, 2013) emphasized that the successful control of a tick population is related not only to the efficacy of an acaricide but also to the deleterious effects that these active agents cause over tick populations in the field, especially with the respect to the reproductive parameters of engorged females. This effect, caused by certain formulations, is termed "pasture cleansing" (Pereira, 2009;Santana et al, 2013;Lopes et al, 2014).…”