Characterization of resistance in cotton genotypes and bioactivity of essential oils and their microemulsions to management of Bemisia tabaci MED (Hemiptera: Aleyrodidae)
Carregando...
Data
2022-07-04
Autores
Santana, Alisson da Silva [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
Moscas-brancas do complexo Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) destacam-se como pragas severas do algodoeiro em todo o mundo. Esses insetos podem ocasionar danos diretos às plantas, por meio da sucção de seiva, além de indiretos, devido ao favorecimento da ocorrência de fumagina e transmissão de vírus. No Brasil, a introdução da espécie B. tabaci Mediterranean (MED) (anteriormente biótipo Q), tem despertado a atenção de produtores e da comunidade científica, uma vez que essa espécie apresenta elevada capacidade de infestação, além de resistência a diversos grupos de inseticidas. Como alternativa ao controle químico, plantas resistentes e derivados botânicos destacam-se como valiosas ferramentas para o manejo integrado de pragas (MIP). No entanto, até o momento, no Brasil, não há estudos abordando a resistência de genótipos de algodoeiro a B. tabaci MED e no tocante a derivados botânicos, a escassez de formulações limita sua utilização no controle de pragas em grandes culturas. Nesse cenário, o objetivo deste trabalho foi identificar fontes de resistência em genótipos de algodoeiro a B. tabaci MED e avaliar a bioatividade de óleos essenciais e suas formulações sobre o inseto. Inicialmente, foram realizados bioensaios de toxicidade para avaliar a eficiência dos óleos essenciais (OEs) de Piper marginatum Jacq. (Piperaceae) e Mansoa alliacea Miers (Bignoniaceae) e suas formulações contra B. tabaci MED. Por fim, para avaliar a possível resistência de genótipos de algodoeiro, foi realizado um ensaio preliminar com 78 genótipos, dos quais 28 foram selecionados para ensaios de antixenose e antibiose. Com base nos resultados obtidos, foi possível observar que os óleos essenciais de P. marginatum e M. alliacea foram tóxicos para ninfas de B. tabaci MED em condições de laboratório e semicampo. Os OEs apresentaram efeitos ovicida e repelente, além de inibir a oviposição e colonização nas folhas/plantas tratadas. Da mesma forma, as microemulsões à base de OEs foram tóxicas contra B. tabaci MED em condições de laboratório e casa de vegetação. Além disso, a eficácia das emulsões foi mantida quando diluídas em água. Nos bioensaios de resistência, os genótipos IAC 23, IAC 25, FM975WS, IAC PV 010-175 foram os menos infestados por adultos de B. tabaci MED, enquanto Aubum 56-7, DP 4049, Express 257, IAC-18, Empire B-4 e Reba B- 50 RR apresentaram o menor número de ovos e IAC 97-2939 “macaco”, 101-102 B, Algodão Indiano e Paymaster 53-523 apresentaram o menor número de ninfas, indicando a ocorrência de antixenose e/ou antibiose. Por outro lado, os genótipos IAC 13-1-76-5366, CNPA 92-1121 e Hi-Bred exibiram antibiose, reduzindo o tempo de desenvolvimento e causando alta mortalidade ninfal. A densidade de glândulas de gossipol correlacionou-se positivamente com a mortalidade ninfal. Com base nesses resultados, é possível concluir que as estratégias de controle aqui estudadas podem ser ferramentas a ser utilizadas no manejo integrado de pragas do algodoeiro no futuro, bem como servir de base para novos estudos visando o controle de B. tabaci MED.
Whiteflies of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex stand out as severe cotton pests worldwide. These insects can cause direct damages to cotton plants through of the continuous sucking of sap as well as indirect damages by favoring sooty mold and transmitting virus. In Brazil, the introduction of B. tabaci Mediterranean (MED) (known previously as Q biotype) has attracted the attention of farmers and the scientific community, once this species presents high infestation capacity, besides resistance to several groups of insecticides. As an alternative to the chemical control, plant resistance and botanical derivatives can be valuable tools for integrated pest management (IPM). However, to date, in Brazil, there are no studies assessing the resistance of cotton genotypes to B. tabaci MED. Regarding botanical derivatives, the lack of formulations limits their use for pest control in crop fields. In this scenario, here we aimed to identify sources of resistance in cotton genotypes to B. tabaci MED and assess the bioactivity of formulations based on essential oils on the insect. Initially, toxicity bioassays were performed to evaluate the efficiency of essential oils (EOs) of Piper marginatum Jacq. (Piperaceae) and Mansoa alliacea Miers (Bignoniaceae) and their formulations against B. tabaci MED. Finally, to evaluate the possible resistance of cotton genotypes, a preliminary assay was carried out with 78 genotypes, of which 28 were selected for antixenosis and antibiosis assays. Based on the results obtained, it was possible to observe that the essential oils of M. alliacea and P. marginatum were toxic against nymphs of B. tabaci MED in laboratory and semifield conditions. The EOs showed ovicidal and repellent effects in addition to inhibiting oviposition and colonization on treated leaves/plants. In the same way, microemulsions based on the EOs were toxic against nymphs of B. tabaci MED in laboratory and greenhouse conditions, demonstrating ovicidal and repellent effects and inhibiting oviposition and colonization on treated leaves/plants. In addition, the efficacy of the emulsions was maintained when diluted in water. Regarding to host resistance assays, the genotypes IAC 23, IAC 25, FM975WS, IAC PV 010-175 were the least infested by adults of B. tabaci MED, while Aubum 56-7, DP 4049, Express 257, IAC-18, Empire B-4 and Reba B-50 RR showed the lowest number of eggs and IAC 97-2939 “macaco”, 101-102 B, Algodão Indiano and Paymaster 53-523 showed the lowest means of nymphs, indicating the occurrence of antixenosis. On the other hand, the genotypes IAC 13-1-76-5366, CNPA 92-1121 and Hi-Bred exhibited antibiosis, reducing the development time and causing high nymphal mortality. The density of gossypol glands was positively correlated with nymphal mortality. Based on these results, it is possible to conclude that the control strategies studied here can be tools to be used in the integrated management of pests in cotton in the future, as well as serve as a basis for new studies aiming to control whiteflies.
Whiteflies of Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) complex stand out as severe cotton pests worldwide. These insects can cause direct damages to cotton plants through of the continuous sucking of sap as well as indirect damages by favoring sooty mold and transmitting virus. In Brazil, the introduction of B. tabaci Mediterranean (MED) (known previously as Q biotype) has attracted the attention of farmers and the scientific community, once this species presents high infestation capacity, besides resistance to several groups of insecticides. As an alternative to the chemical control, plant resistance and botanical derivatives can be valuable tools for integrated pest management (IPM). However, to date, in Brazil, there are no studies assessing the resistance of cotton genotypes to B. tabaci MED. Regarding botanical derivatives, the lack of formulations limits their use for pest control in crop fields. In this scenario, here we aimed to identify sources of resistance in cotton genotypes to B. tabaci MED and assess the bioactivity of formulations based on essential oils on the insect. Initially, toxicity bioassays were performed to evaluate the efficiency of essential oils (EOs) of Piper marginatum Jacq. (Piperaceae) and Mansoa alliacea Miers (Bignoniaceae) and their formulations against B. tabaci MED. Finally, to evaluate the possible resistance of cotton genotypes, a preliminary assay was carried out with 78 genotypes, of which 28 were selected for antixenosis and antibiosis assays. Based on the results obtained, it was possible to observe that the essential oils of M. alliacea and P. marginatum were toxic against nymphs of B. tabaci MED in laboratory and semifield conditions. The EOs showed ovicidal and repellent effects in addition to inhibiting oviposition and colonization on treated leaves/plants. In the same way, microemulsions based on the EOs were toxic against nymphs of B. tabaci MED in laboratory and greenhouse conditions, demonstrating ovicidal and repellent effects and inhibiting oviposition and colonization on treated leaves/plants. In addition, the efficacy of the emulsions was maintained when diluted in water. Regarding to host resistance assays, the genotypes IAC 23, IAC 25, FM975WS, IAC PV 010-175 were the least infested by adults of B. tabaci MED, while Aubum 56-7, DP 4049, Express 257, IAC-18, Empire B-4 and Reba B-50 RR showed the lowest number of eggs and IAC 97-2939 “macaco”, 101-102 B, Algodão Indiano and Paymaster 53-523 showed the lowest means of nymphs, indicating the occurrence of antixenosis. On the other hand, the genotypes IAC 13-1-76-5366, CNPA 92-1121 and Hi-Bred exhibited antibiosis, reducing the development time and causing high nymphal mortality. The density of gossypol glands was positively correlated with nymphal mortality. Based on these results, it is possible to conclude that the control strategies studied here can be tools to be used in the integrated management of pests in cotton in the future, as well as serve as a basis for new studies aiming to control whiteflies.
Descrição
Palavras-chave
Plant resistance, Botanical insecticides, Alternative control, Whitefly, Antixenosis, Antibiosis, Resistência de plantas, Inseticidas botânicos, Controle alternativo