Egletes viscosa (Asteraceae) and Lippia schaueriana (Verbenaceae) essential oils and its effects on the reproductive biology and morphology (Gené's organ, ovary and synganglion) of Rhipicephalus sanguineus sensu lato (Acari:Ixodidae) ticks and on the thryroid and liver of Mus musculus mice

Author(s)

Melissa Carolina Pereira

• Document type: Master's Dissertation
• Press: Rio Claro. 2021-09-03.
• Institution: Universidade Estadual Paulista (Unesp). Instituto de Biociências. Rio Claro
• Defense date: 2021-08-03
• Advisor: Maria Izabel Souza Camargo; Luís Adriano Anholeto

Abstract

The data obtained in this study confirmed the acaricidal potential of essential oils (EOs) extracted from Egletes viscosa Less. and Lippia schaueriana Mart. at the concentrations of 12.5, 25 e 50 mg/mL against the brown dog tick Rhipicephalus sanguineus sensu lato (s. l.) engorged females. The yield of both oils was 1.2% v/m and the analyses identified 27 components in E. viscosa and 18 in L. schaueriana, whose major compounds was cis-isopinocarveyl acetate (68.41%) and piperitenone oxide (64.36%), respectively. Both EOs reduced significantly (p<0.05) oviposition and the eggs viability at the concentrations of 25 and 50 mg/mL. The control percentages of the E. viscosa oil were 58.9%, 70.8% and 92.7% at the concentrations of 12.5, 25 and 50 mg/mL, respectively. In the same concentrations, the efficacy of L. schaueriana was 39.3%, 53.4% and 84.6%. The eggs produced by the females exposed to all concentrations of the EOs presented several morphological alterations (dehydrated, darkened and disaggregated aspect). The engorged females exposed to the oils showed severe alterations in Gene’s organ, both in the tubular and accessory glands, especially at the concentrations of 25 and 50 mg/mL, which induced this organ’s degeneration. When exposed to EOs sublethal concentrations, the oocytes of the engorged females studied here also underwent extensive changes, with exposure to the EO of L. schaueriana being more agressive in early stages oocytes (I - III) while all concentrations of the EO of E. viscosa were able to cause intense damage to oocytes I to V. Both EOs interfered in the dynamics of vitellogenesis. The EOs of E. viscosa and L. schaueriana presented highly neurotoxic potential, since they were able to induce degeneration in the nervous tissue at all concentrations analysed and in dose-dependent maner. Furthermore, the oils studied here caused great damage to the liver and thyroid of mice exposed to the concentration of 50 mg/mL, inducing degeneration in both tissues to such an extent that they certainly harmed the physiology of these organs. (AU)

• FAPESP's process: 19/02831-3 - Responses to Rhipicephalus sanguineus lato sensu (Acari:Ixodidae) and Mus musculus mice to the exposure to Egletes viscosa (Asteraceae) and Lippia schaueriana (Verbenaceae) oils, potential natural acaricides
• Grantee: Melissa Carolina Pereira
• Support Opportunities: Scholarships in Brazil - Master