Effect of Tagetes minuta essential oil on the central nervous system (synganglion) of unfed Rhipicephalus sanguineus sensu lato ticks

Abstract

The Rhipicephalus sanguineus sensu lato tick, (Acari Ixodidae) is considered as sanitary concern due to its role as a vector. Tick strain resistant to synthetic acaricides has caused difficulties in its control, besides synthetic acaricides are harmful to the environment and the health of other animals. The use of plants with acaricidal and repellent properties has shown promising results under laboratory conditions with characteristics that resemble an ideal acaricide/insecticide. The genus Tagetes spp. excels for its use as traditional pest control in households and plantations and also for its potential as acaricide/insecticide in laboratory conditions against R. sanguineus. The first aim of this research was to evaluate the effect of different doses of Tagetes minuta essential oil (TMEO) on the central nervous system (synganglio) in unfeed R. sanguineus adults. The synganglion histologic analysis showed a remarkable effect with signs of cell damage including volume increase, loss of shape, and vacuolization, in addition to chromatin alterations such as condensation, margination, and fragmentation. TMEO were analyzed by gas chromatography coupled with mass spectrometry showing the presence of 21 compounds that according to its chemical structure are classified as terpenoids, of these compounds (Z)-β-ocimene, o-cimene, (Z)-tagetone, and verbenona were found in major quantities. The Gas chromatography analysis showed a composition variability related to the incidence of biotic and abiotic factors.