Evaluation of the sublethal effects of carvacrol on the reproductive performance and oocyte morphology in Rhipicephalus (Boophilus) microplus engorged female ticks (CANESTRINI, 1887) (Acari: Ixodidae)

• Grant number: 14/18453-4
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: January 01, 2015
• End date: April 26, 2015
• Field of knowledge: Biological Sciences - Zoology - Applied Zoology
• Principal Investigator: Maria Izabel Souza Camargo
• Grantee: Rafael Neodini Remedio
• Host Institution: Instituto de Biociências (IB). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

Rhipicephalus (Boophilus) microplus ticks, also known as cattle-ticks, are responsible for huge economic losses annually, due to their feeding habits which undermine health and transmit diseases to their preferred hosts, the bovines. For this reason, countless control strategies have been encouraged, being the application of synthetic acaricides the most widely used. However, the development of resistant strains of ticks to these compounds, as well as their toxic effects to hosts and environment, have led the scientific community to search for alternative control methods, such as the use of plant extracts and their active compounds. In this context, the use of the monoterpene carvacrol has been recognized as a promising alternative, since it has acaricidal and repellent effects, besides being considered a potentially safe method. Based on this information, this work aims to evaluate the acaricidal potential of carvacrol and its efficiency on the reproductive control of cattle-tick engorged females. The susceptibility of R. microplus to carvacrol, diluted in a hydroethanolic solution, will be evaluated by determining the lethal concentration for 50 and 99% of the ticks. From the obtained values, the effects of sublethal concentrations of this compound on reproductive performance of these arthropods will be analyzed, associating the data obtained to the morphological characteristics of their reproductive system. For this purpose, techniques in immunohistochemistry, fluorescence and ultrastructure will be performed. The ultrastructural results will be evaluated using a standardized protocol for semiquantitative analysis, proposed in this study. (AU)