Avaliação acaricida de derivados naturais de Achyrocline satureioides e de Schinus lentiscifolius em associação com produtos biotecnológicos obtidos de fungos entomopatogênicos sobre o carrapato do boi Rhipicephalus (Boophilus) microplus
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Data
2021-03-29
Autores
Fantatto, Rafaela Regina
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Universidade Estadual Paulista (Unesp)
Resumo
Apesar da importância social e comercial da bovinocultura, infestações por ectoparasitas, como o carrapato Rhipicephalus (Boophilus) microplus, apresentam-se como um grande empecilho econômico. O controle atualmente é realizado por meio de carrapaticidas sintéticos e o seu uso indiscriminado tem contribuído para o surgimento da resistência dos parasitas à maioria das moléculas disponíveis. Assim, alternativas efetivas, economicamente viáveis e potencialmente seguras devem ser investigadas, como o uso de derivados naturais associados a fungos entomopatogênicos. Esse estudo avaliou extrativos vegetais de Achyrocline satureioides (Lam) D.C. e Schinus lentiscifolius (March.) D. C., associados e não associados ao fungo entomopatogênico Beauveria bassiana, bem como à enzima quitinase por ele produzida, sobre diferentes estágios do ciclo de vida do carrapato do boi R.(B.) microplus. A atividade carrapaticida dos extratos vegetais, do fungo, das associações dos mesmos e quitinase, foi analisada por testes in vitro tais como o teste de imersão de fêmeas ingurgitadas, teste de contato em papel impregnado e teste de imersão de larvas. Os resultados obtidos demonstraram que os extrativos, quando associados ao fungo tem sua ação potencializada chegando a atingir 100% de mortalidade sobre larvas. Outro fator relevante é que o teste de imersão de larvas permite uma melhor avaliação dos produtos analisados, devido ao tempo que fica em contato com as larvas. Frente às fêmeas ingurgitadas os resultados não foram significativos devido ao tempo que o fungo necessita para agir e com isso não foi possível interromper o ciclo. A utilização de quitinase sobre larvas não apresentou mortalidade superior à utilização de extratos sendo apenas efetiva quando o tratamento consistiu de associação de partição hexânica de A. satureioides e enzima. Os resultados obtidos com as espécies vegetais associados ao fungo são considerados promissores e abrem novas perspectivas de estudos.
Despite the social and commercial importance of cattle farming, ectoparasite infestations, such as the tick Rhipicephalus (Boophilus) microplus, present themselves as a major economic obstacle. The control is currently carried out using synthetic acaricides and its indiscriminate use has contributed to the emergence of parasite resistance to most of the available molecules. Thus, potential alternatives that are effective, economically viable and safe should be investigated, such as the use of natural derivatives associated with entomopathogenic fungi. This study evaluated plant extracts of Achyrocline satureioides (Lam.) D.C. and Schinus lentiscifolius (March.) D.C. associated and not associated with the entomopathogenic fungus Beauveria bassiana, as well as the chitinase enzyme produced by it, over different stages of the life cycle of the cattle tick R. (B.) microplus. The acaricide activity of plant extracts, fungus, their associations and chitinase, was analyzed by in vitro tests such as the immersion test of engorged females, contact test on impregnated paper and larvae immersion test. The results obtained demonstrated that the extractives, when associated with the fungus, have their potentiated action reaching 100% mortality on larvae. Another relevant factor is that the larvae immersion test allows a better evaluation of the evaluated products, due to the time that is in contact with the larvae. The results were not significant compared to engorged females due to the time that the fungus needs to act and, therefore, it was not possible to interrupt the cycle. The use of chitinase on larvae did not present a higher mortality than the use of extracts, being only effective when the treatment consisted of an association of hexane partition of A. satureioides and enzyme. The results obtained with the plant species associated with the fungus are considered promising and allow possibilities for further studies.
Despite the social and commercial importance of cattle farming, ectoparasite infestations, such as the tick Rhipicephalus (Boophilus) microplus, present themselves as a major economic obstacle. The control is currently carried out using synthetic acaricides and its indiscriminate use has contributed to the emergence of parasite resistance to most of the available molecules. Thus, potential alternatives that are effective, economically viable and safe should be investigated, such as the use of natural derivatives associated with entomopathogenic fungi. This study evaluated plant extracts of Achyrocline satureioides (Lam.) D.C. and Schinus lentiscifolius (March.) D.C. associated and not associated with the entomopathogenic fungus Beauveria bassiana, as well as the chitinase enzyme produced by it, over different stages of the life cycle of the cattle tick R. (B.) microplus. The acaricide activity of plant extracts, fungus, their associations and chitinase, was analyzed by in vitro tests such as the immersion test of engorged females, contact test on impregnated paper and larvae immersion test. The results obtained demonstrated that the extractives, when associated with the fungus, have their potentiated action reaching 100% mortality on larvae. Another relevant factor is that the larvae immersion test allows a better evaluation of the evaluated products, due to the time that is in contact with the larvae. The results were not significant compared to engorged females due to the time that the fungus needs to act and, therefore, it was not possible to interrupt the cycle. The use of chitinase on larvae did not present a higher mortality than the use of extracts, being only effective when the treatment consisted of an association of hexane partition of A. satureioides and enzyme. The results obtained with the plant species associated with the fungus are considered promising and allow possibilities for further studies.
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Palavras-chave
Rhipicephalus (Boophilus) microplus, Achyrocline satureioides, Schinus lentiscifolius, Beauveria bassiana, quitinase