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BACKGROUND Although ants are common insects in agricultural ecosystems, few studies have considered how xenobiotics might induce physiological and morphological alterations in these insects. This study aimed to verify the neurotoxic action of sublethal doses of fipronil on the mushroom bodies of brains from the leaf-cutting ant Atta sexdens rubropilosa through immunocytochemistry analysis for the protein synapsin. RESULTS The LD50 value was established as 1.42 ng ant−1, and the sublethal doses used were LD50/10 and LD50/100. Synapsin labelling was more evident in the brains extracted from ants exposed to the insecticide, specifically in the regions of glia in the mushroom bodies, compared with the control group. It was possible to measure the intensity of emitted fluorescence in the areas of the mushroom bodies, and a statistical test showed differences between the control group and the treatment group. CONCLUSION Thus, it is concluded that sublethal doses of the insecticide fipronil intensified synapsin immunostaining, suggesting an increased release of neurotransmitters, which may be linked to neurotoxicity and overexcitation. These sublethal doses may have two different effects: compromising the operation and maintenance of the colony and leading to the establishment of resistance in insects. © 2015 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Ticks are among the most important pathogen vectors worldwide, and the knowledge of their internal and external morphology may provide relevant information that will allow an adequate control of these animals. In this sense, the integument gains prominence, not only because of its wide capacity of expansion, but also due to the fact that this region is usually the first site of contact with natural and synthetic acaricides. Therefore, this study aimed to describe the morphology of alloscutal integument of R. sanguineus female ticks in three different feeding stages by means of histological and ultramorphological analysis. Significant differences were observed in all stages, with respect to the size of cells and layers, and to cuticle unfolding throughout the feeding process. Cuticle is divided into two main layers, the epicuticle and the procuticle, and is separated from a unistratified epithelium by a subcuticular layer. Procuticle, in turn, is divided into two layers, the endocuticle and exocuticle. Unfed female ticks showed cuticle with numerous folds, which decrease in quantity as the feeding expansion of the whole animal occurs. Opening of dermal glands and presence of setae also differed among groups. [ABSTRACT FROM AUTHOR]

The tick species Amblyomma cajennense is of great medical importance, as it is the vector of the Rickettsia rickettsii, agent of Rocky Mountain spotted fever. The objective of this study was to perform a morphological and histological analysis of the male reproductive system of fed and unfed A. cajennense. The male reproductive system is formed by a pair of tubular testes dorsolaterally arranged in opisthosoma. They were divided into three regions: proximal region (next to vas deferens), median region and distal region (nearest to the blind ending of testis). Proximal regions are connected to the seminal vesicles by the deferent ducts and to accessory glands, similar to what was observed for other Ixodidae. Feeding plays a fundamental role in the development of the reproductive system, as in unfed individuals, the testes, the seminal vesicles and the accessory glands were smaller comparing with the fed individuals. In addition, the prospermia, precursors of the spermatozoa, were only observed in fed individuals. The germ cells were organized in spermatocysts, enveloped by a connective tissue. The cells in more advanced stages of spermatogenesis were localized in the distal region, in accord with studies in other ticks, but opposite to what was observed for other arthropods. [ABSTRACT FROM AUTHOR]