The objective of this study was to evaluate the larvicidal potential of a crude ethanol extract (CEE) of soapberry Sapindus saponaria stem peel on the cattle tick Boophilus microplus. Tick larvae obtained by incubating engorged females, collected from naturally infested cattle, were placed in envelopes of filter paper impregnated with different concentrations of CEE in the test group, and distilled water in the control group. Four repetitions were made with each solution (n>120). Mortality was observed after 48 hours. Lethal concentration values of 1,258 ppm (LC50) and 6,360 ppm (LC99) were obtained.

Amblyomma cajennense or the Cayenne tick is a three-host ixodid tick species of low parasitic specificity that is the principal vector of Brazilian spotted fever. The primary objective of this study was to evaluate the possible development of resistance by adult specimens of A. cajennense to deltamethrin, a synthetic pyrethroid insecticide and the principal miticide/acaricide commercially available in the region. The second objective was to monitor the susceptibility and/or resistance of larvae of this species to 12 synthetic acaricide formulations selected from the principal pesticides available in Goiás for the control of ticks. Unfed male and female adult specimens of A. cajennense were collected from leaves of bushes along a nature trail in the municipality of Caldas Novas, Goiás, Brazil. They were submitted to immersion in the highest recommended dose of deltamethrin and subsequently, were placed in contact with filter paper impregnated with the substance. The toxicological effects caused by the insecticide were observed every 6 h over a 36 h period. To obtain larvae, engorged females of A. cajennense were collected from naturally infested horses that had been free of acaricidal residue for at least 45 days, in farms situated in five different municipalities in the state (Caldas Novas, Hidrolândia, Goiás, Terezópolis and Goiânia). The larvae were exposed to different concentrations of 12 commercially available acaricidal formulations using the larval packet test (LPT) method. The control groups were treated with distilled water alone. The bioassays were performed in quadruplicate at a temperature of 27 °C, relative air humidity > 80% and 12 h light/dark cycles. The mean percentage of mortality MX was 72.6% in the adult specimens after 24 h of exposure to the dose of deltamethrin recommended by the manufacturer, characterizing a status of resistance. MX of 82, 89, 89.6 and 90% of the larvae were obtained, respectively, for deltamethrin, cypermethrin + piperonyl butoxide (PBO), amitraz and permethrin, characterizing a status of probable resistance of the larvae to these acaricides. No significant mortality was found in the control groups.

The action of fenthion was studied in a 15% epicutaneous formulation upon Rhipicephalus sanguineus, which may transmit pathogens to men and other animals, such as Ehrlichia, Babesia and Ricketsia. Dogs were artificially infected for the trial. The fenthion bioassays were begun four months after artificial infestation. The test group, having a mean of 186 ticks per dog, received the formulation dosage according to body weight on the neck region. Tick counts were performed, considering diameters > or = 2mm, during 11 days of treatment, in the most affected body areas: back, ears and paws. Before the application of fenthion in the dogs, it were observed an average 43.3% ticks in the ears, 38.1% in the back area and 17.6% in the paws. The number of ticks in dogs decreased by 36.2%, 63.8%, 82.7%, 67%, 40% and 4.9%, respectively on days 1, 2, 3, 5, 7, 9 and 11 after treatment. R. sanguineus anti-tick activity, lower than that officially recommended, was verified. The number of ticks increased progressively after the 5th day, demonstrating residual insecticide inefficacy. The results obtained did not indicate the use of this formulation, at the tested dosage, as an elective measure for R. sanguineus control.

It has been observed that formulations of deltamethrin developed for disinsectization of infested places and control of parasitic arthropods of bovines and equines have frequently been used by breeders of dogs to control ticks in their animals and kennels, but without due consideration of the correct dosage or means of application. With the purpose of evaluating the efficacy of this product on Rhipicephalus sanguineus, bioassays were realized with larvae at 27+/-1 degrees C, UR>80% and light period of 12 hours. The mortality and toxicological effects were observed for 30 h, at 6 h intervals. Important toxicological effects were observed on the larvae, such as lack of co-ordination, knock-down and paralysis followed by death, although the lethal capacity of the product after 30 h was low, with mean mortality of only 34%, 40.2%, 46% and 57.6% respectively, for the 0.5 ml/l; 1 ml/l; 2 ml/l/; and 3 ml/l dosages. There was no mortality in the control group. The results obtained did not indicate the use of this formulation, in the tested dosages, as a method of choice for R. sanguineus control.

The acaricidal potential of the crude ethanolic extract (c.e.e.) of the stem peel of Magonia pubescens was evaluated against larvae of Rhipicephalus (Boophilus) microplus. The larvae were placed in filter paper envelopes impregnated with different concentrations of c.e.e., dissolved in dimethylsulfoxide (DMSO) and distilled water for determination of lethal concentrations (LC). The following treatments were used: 1. Envelopes of dry filter paper; 2. Envelopes of filter paper moistened with distilled water; 3. Envelopes of filter paper moistened with a solution of DMSO in distilled water; and 4. Envelopes moistened with 2 mL of each concentration of the c.e.e. to be tested. The bioassays were carried out in quadruplicate at 27°±1° C and RH e"80% and 12h light. Mortality was observed after 48 h, LC50 and LC99 values of 365 and 4,000 ppm being obtained. There was no significant mortality in larvae exposed to the first three treatments (p < 0.05).
Este trabalho objetivou avaliar o potencial acaricida do extrato-bruto etanólico (e.b.e.) da casca do caule de Magonia pubescens sobre larvas do carrapato bovino Rhipicephalus (Boophilus) microplus. As larvas foram acondicionadas em B.O.D. climatizada, em envelopes de papel filtro impregnados com diferentes concentrações do e.b.e., solubilizado com dimetilsulfóxido (DMSO) e água destilada, para determinação das Concentrações Letais (CL). Foram realizados os seguintes tratamentos: 1. envelopes de papel filtro seco; 2. envelopes de papel filtro umedecidos com água destilada; 3. envelopes de papel filtro umedecidos com solução de DMSO e água destilada; e 4. envelopes umedecidos com 2 mL de cada concentração do e.b.e. testada. Os bioensaios foram feitos em quadruplicata, em uma câmara climatizada a 27°±1° C, URe"80% e fotofase natural de 12 horas. A mortalidade foi observada após 48h. Obtiveram-se as CL50 de 365 e CL99 de 4.000 ppm. Não houve mortalidade significativa para os três primeiros tratamentos (p<0,05)