Morphological evaluation of the liver in Wistar rats inoculated with Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) salivary gland extracts.

The Rhipicephalus sanguineus is considered a species of medical and veterinary importance. The feeding process of these animals occurs due to the combined action of their mouthparts and the saliva produced by the salivary glands, vital organs for the biological success of the ticks. In addition, these glands act as storage sites for the pathogens transmitted to the host through the inoculation of the saliva. In this sense, the present study had the objective to analyze the behavior of male Wistar rat hepatic cells submitted to in vivo application of the salivary gland extract (SGE) obtained from R. sanguineus female ticks. The study involved five groups (four male adults each): CG (non-inoculated individuals); PBS1 (one phosphate buffer saline injection); PBS2 (two PBS injections); SGE1 (one injection of SGE at 0.04 µg/µL) and SGE2 (two injections of SGE at 0.04 µg/µL). After the exposures, the livers were removed and submitted to the following histological and histochemical stains: HE, toluidine blue, Xylidine Ponceau, alcian blue/PAS, and osmium-imidazole. The results showed that both the PBS and the SGE caused hepatic moderate alterations, such as: (a) emergence of lipid plaques among the hepatic cords; (b) cytoplasmic vacuolation of the hepatic cells; (c) hepatocytes showing pyknotic nuclei; (d) presence of homogeneous or granular secretion in the cytoplasm of the hepatocytes. Despite the slight morphological alterations observed in the hepatic cells and tissue, the latter did not show signs of disorganization after the exposure to the extracts.

The effects of neem oil (Azadirachta indica A. JUSS) enriched with different concentrations of azadirachtin on the integument of semi-engorged Rhipicephalus sanguineus sensu lato (Acari: Ixodidae) females.

Several studies searching for methods to control Rhipicephalus sanguineus s.l., (dog tick) infestations have been developed aiming to minimize the damages caused by these ectoparasites to the hosts and the environment, which is harmed by the indiscriminate use of toxic acaricide products. In this scenario, neem oil has been used as a natural alternative against ticks, once this chemical has repellent properties and interferes in the growth regulation of these ectoparasites, inhibiting ecdysis. The present study evaluated the effects of azadirachtin-enriched neem oil on the integument of semi-engorged R.sanguineus s.l., females through morphohistological techniques. The results showed the occurrence of significant morphological and histochemical alterations, mainly in the females exposed to higher concentrations, which demonstrates the dose-dependent action of the chemical. A decrease in the cuticle thickness was observed, as well as a modification in the distribution of the epithelial cells, which displayed pyknotic and fragmented nuclei, and intensely vacuolated cytoplasm, indicating that these cells would be undergoing death processes. These morphological alterations observed in the integument of the females exposed to the azadirachtin-enriched neem oil encourage the use of this chemical as a strategy to control these ectoparasites.

Potential of the chemical dinotefuran in the control of Rhipicephalus sanguineus (Latreille, 1806) (Acari: Ixodidae) semi-engorged female ticks.

Ticks are vectors of several pathogens to vertebrates, including the human being. They produce lesions on the hosts during the blood feeding and great economic losses. Several chemical acaricides have been used in an attempt to control tick infestations; however these substances are harmful to both the human being and non-target organisms, and to the environment. Therefore, there is a need to fight these ectoparasites through less harmful methods, less aggressive to the environment, non-target organisms and to the human health. The present study examined the efficacy of dinotefuran on the susceptibility of Rhipicephalus sanguineus semi-engorged females exposed to different concentrations of the product. Its lethal concentration of 50% (LC50) at 95% confidence interval was determined. The ticks were immersed in Petri dishes containing different concentrations of dinotefuran or distilled water for 5 minutes and then dried and maintained in an incubator for 7 days. The results showed the daily number of dead R. sanguineus semi-engorged females after being treated with different concentrations of dinotefuran. The mortality data in bioassay 2 were subjected to Probit analysis, where a LC50 of 10,182.253 ppm (8725.987-13,440.084) and 95% confidence interval were estimated. The susceptibility of R. sanguineus semi-engorged females to dinotefuran in higher concentrations of the acaricide was demonstrated, indicating that its effect is probably dose-dependent. In addition, the action of dinotefuran was slow and gradual, interfering in the development and growth of the individuals throughout the observation period (7 days).

Biochemical and cytochemical studies of the enzymatic activity of the venom glands of workers of honey bee Apis mellifera L. (Hymenoptera, Apidae).

Biochemical studies revealed that the activity of some hydrolytic enzymes from the venom glands of honey bee Apis mellifera was higher in workers of 14 days of age than in those of 40 days. Among these enzymes, the highest activity was recorded for acid phosphatase, which was cytochemically detected throughout the length of the secretory filament and surrounding the canaliculi of the distal region of the reservoir. The acid phosphatase was considered to be a typical secretion product, since it was present in the cytoplasm as well as in the canaliculi of the secretory cells.