Banca de QUALIFICAÇÃO: ADRIANI DA SILVA CARNEIRO LOPES

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ADRIANI DA SILVA CARNEIRO LOPES
DATE: 28/05/2025
TIME: 09:00
LOCAL: Ambiente remoto - Google meet
TITLE:

 Acaricidal effect of Metarhizium pingshaense associated with Mentha piperita essential oil, Menthol and Menthone on Psoroptes ovis and Dermanyssus gallinae.

KEY WORDS:

Mites, biological control, peppermint, entomopathogenic fungi.

PAGES: 79
BIG AREA: Ciências Agrárias
AREA: Medicina Veterinária
SUBÁREA: Medicina Veterinária Preventiva
SPECIALTY: Doenças Parasitárias de Animais
SUMMARY:

The Psoroptes ovis mite is popularly known as the psoroptic mange mite, sheep mite, rabbit ear mange mite, among others. It is an Astigmata mite, non-burrowing and commonly causes infestation in production animals. Individuals infested with this ectoparasite tend to suffer from intense itching, crust formation in the affected area, alopecia and there is the possibility of secondary infections due to the parasitic condition. Currently, the control of these ectoparasites is carried out with different synthetic acaricides, from the most varied classes, such as: pyrethroids, organophosphates, macrocyclic lactones, among others. However, the indiscriminate use of these agents has caused resistance to some classes of synthetic acaricides. From this, studies on control alternatives are carried out, including the use of entomopathogenic fungi and essential oils to enable the control of these ectoparasites, since the literature cites the efficacy of these biological control agents for other arthropods of veterinary importance. In this perspective, the present study aimed to evaluate the efficacy of a native isolate of Metarhizium pingshaense associated with the essential oil of Mentha piperita and the isolated compounds Menthol and Menthone to control the mite P. ovis. For the tests, mites were collected from crusts obtained from the auditory canal of naturally infested rabbits (Oryctolagus cuniculus) and taken to the laboratory for in vitro tests. Initially, a compatibility test was performed between the fungal isolate and the essential oil at different concentrations and it was shown that there is compatibility between them, allowing in vitro mortality tests with the fungus + oil association to be performed. A posteriori, in vitro tests were performed with groups treated only with fungus at different concentrations and in association with M. piperita essential oil, menthol or menthone at a concentration of 0.01 mg/mL, in addition to a control group. It was observed that groups treated only with the fungus at a concentration of 1 × 108 conidia/mL alone or in association with the essential oil, menthol or menthone after 48h of treatment did not differ statistically from each other, and all led to a mortality of more than 90% of the mites. After 96h of treatment, it was observed that the essential oil, menthol and menthone groups, alone and those associated with the fungus at a concentration of 1 × 107 conidia/mL also caused mortality in more than 90% of the mites, being statistically equivalent to the groups mentioned at 48h. Furthermore, an electron microscopy analysis was performed with mites after 24h and 48h of treatment, for all groups used in the biological assays, a large development of fungal mycelium was observed in the groups treated with the isolate of M. pingshaense, alone or in association, but no significant morphological changes were observed in the groups treated with the associations that contained fungus with essential oil or isolated compound. Furthermore, the occurrence of fungal penetration was not observed, suggesting that the mechanism of action for the mortality of mites is a mechanical effect that leads to asphyxiation. Therefore, the results demonstrated reinforce the need for further studies related to the mechanism of action of entomopathogenic fungi and essential oils for the control of P. ovis, so that we can understand the efficient forms of biological control for mites.

COMMITTEE MEMBERS:
Presidente - 2221855 - PATRICIA SILVA GOLO
Interna - 1282902 - KATIA MARIA FAMADAS
Externa à Instituição - MARIANA GUEDES CAMARGO - UFRRJ
Externa à Instituição - SIMONE PATRICIA CARNEIRO DE FREITAS