Morpho-ultrastructural alterations in the salivary glands of semi-engorged Riphicephalus sanguineus s.l. females subjected to permethrin 

Abstract

Ticks are arthropods of great medical-veterinary importance, and several methods have been developed to control them. The synthetic acaricide permethrin is one of the most widely used substances to control this pest. The present study brings cytochemical and ultrastructural data on the alterations in the salivary gland cells of Rhipicephalus sanguineus sensu lato semi-engorged females subjected to 206, 1031, and 2062 ppm of permethrin, showing that this chemical acts on the glandular acini, affecting the morpho-physiology of their cells, making them irregular, causing intense cytoplasmic vacuolation, altering the mitochondria and causing the emergence of lysosomes, myelin figures and spherocrystals. In addition, the results demonstrated that the chemical affected the nuclei and nucleoli of the cells, causing alterations in size, disorganizing and fragmenting them. Such alterations were mainly observed when processes of apoptotic death occurred, and indicated the occurrence of precocious degeneration of the glandular tissue caused by the exposure to the product, even in lower concentrations than the ones recommended by the manufacturer. Under normal conditions, this process would only occur in the end of the engorgement period. Therefore, these findings confirmed and demonstrated that, even at low concentrations, this acaricide would be able to accelerate the process of glandular tissue degeneration through atypical cell death, where the cell death by apoptosis (fragmentation) and autophagy (vacuolation) occur simultaneously.