Relações tróficas entre Euborellia annulipes (Lucas) (Dermaptera: Anisolabididae) e Bacillus thuringiensis no manejo de Plutella xylostella (L.) (Lepidoptera: Plutellidae)
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Data
2020-08-24
Autores
Nunes, Gilmar da Silva [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
As brássicas são cultivadas no mundo inteiro e o uso de Bacillus thuringiensis (Bt) na forma de bioinseticidas tem se destacado no controle da praga-chave, Plutella xylostella (Lepidoptera: Plutellidae). A espécie de tesourinha Euborellia annulipes (Dermaptera: Anisolabididae) está associada à predação desses insetos-praga e podem auxiliar no controle biológico, mas efeitos adversos de Bt em inimigos naturais são preocupações que também vêm sendo levantadas e algumas interações entre tesourinhas e entomopatógenos ainda são pouco compreendidas. Objetivou-se avaliar os efeitos indiretos de B. thuringiensis em aspectos da biologia de E. annulipes quando alimentada com P. xylostella, e no comportamento de predação da tesourinha. Lagartas de P. xylostella não infectadas e infectadas com dois bioinseticidas Dipel®WG (Bt kurstaki) e XenTari®WG (Bt aizawai) nas doses recomendadas pelos fabricantes, foram fornecidas como alimento ao predador. Foram avaliados os efeitos de Bt no desenvolvimento biológico, predação, peso, preferência alimentar, em diferentes condições de escolha, e na resposta funcional do predador. Não houve efeito deletério de Bt no desenvolvimento, mas observou-se que a alimentação com lagartas infectadas afetou a predação por ninfas e por fêmeas, levando-as a consumir mais presas, e a fertilidade do predador, reduzindo a taxa de eclosão e de reprodução líquida. Em condições sem chance de escolha houve menor consumo de lagartas não infectadas, mas com escolha, elas foram preferidas quando comparadas àquelas infectadas com Dipel®. A taxa de predação da tesourinha aumentou em função do aumento da densidade populacional da presa, mas a resposta funcional não foi alterada, sendo do tipo II. O predador investiu menos tempo de manipulação em presas infectadas com Bt e a taxa máxima de predação aumentou. Bioinseticidas Bt usados para o manejo de P. xylostella causam efeitos colaterais no desenvolvimento biológico e afetam indiretamente a predação de E. annulipes. Os achados desta pesquisa podem ser aplicados às abordagens do manejo integrado de pragas e apontam possíveis impactos ecológicos de Bt em tesourinhas.
The cruciferous are cultivated worldwide and using Bacillus thuringiensis (Bt) as bioinsecticides stands out in the control of the major insect-pest Plutella xylostella (Lepidoptera: Plutellidae). The ringlegged earwig Euborellia annulipes (Dermpatera: Anisolabididae) is associated with predation of some of those insect-pests and can assist biological control; however, adverse effects on non-target natural enemies are concerns that also have been raised and interactions between earwigs and entomopathogens are still poorly understood. We aimed to evaluate the indirect effects of Bt-bioinsecticides in the life-history traits of E. annulipes fed on P. xylostella and in the earwig’s predation behavior. Uninfected and infected P. xylostella larvae with two bioinsecticides Dipel®WG (Bt kurstaki) and XenTari®WG (Bt aizawai) at manufacturer recommended doses were provided as food for the predator. We evaluated the side effects on the biological development, predation, weight, feeding preference, under different choice conditions, and on the functional response of the predator. There were no harmful effects of Bt on the development of nymphs and adults, but feeding with Bt-infected larvae affected the predation of nymphs and females, leading them to consume more prey, as well as predator fertility, reducing its hatching rate and net reproductive rate. In the no-choice condition, uninfected larvae were less consumed; however, under free choice, they were preferred compared to Dipel®-infected larvae. The ring-legged earwig’s predation rate was increased as prey population density increase, but the type of functional response was not affected, being type II. The predator invested the lowest amount of handling time on Bt-fed prey and the maximum predation rate increased. Bt-based bioinsecticides used to control P. xylostella cause side effects on the biological development and affect the predation of E. annulipes indirectly. Our findings may be applied to the integrated pest management approaches and point out possible ecological impacts of Bt on earwigs.
The cruciferous are cultivated worldwide and using Bacillus thuringiensis (Bt) as bioinsecticides stands out in the control of the major insect-pest Plutella xylostella (Lepidoptera: Plutellidae). The ringlegged earwig Euborellia annulipes (Dermpatera: Anisolabididae) is associated with predation of some of those insect-pests and can assist biological control; however, adverse effects on non-target natural enemies are concerns that also have been raised and interactions between earwigs and entomopathogens are still poorly understood. We aimed to evaluate the indirect effects of Bt-bioinsecticides in the life-history traits of E. annulipes fed on P. xylostella and in the earwig’s predation behavior. Uninfected and infected P. xylostella larvae with two bioinsecticides Dipel®WG (Bt kurstaki) and XenTari®WG (Bt aizawai) at manufacturer recommended doses were provided as food for the predator. We evaluated the side effects on the biological development, predation, weight, feeding preference, under different choice conditions, and on the functional response of the predator. There were no harmful effects of Bt on the development of nymphs and adults, but feeding with Bt-infected larvae affected the predation of nymphs and females, leading them to consume more prey, as well as predator fertility, reducing its hatching rate and net reproductive rate. In the no-choice condition, uninfected larvae were less consumed; however, under free choice, they were preferred compared to Dipel®-infected larvae. The ring-legged earwig’s predation rate was increased as prey population density increase, but the type of functional response was not affected, being type II. The predator invested the lowest amount of handling time on Bt-fed prey and the maximum predation rate increased. Bt-based bioinsecticides used to control P. xylostella cause side effects on the biological development and affect the predation of E. annulipes indirectly. Our findings may be applied to the integrated pest management approaches and point out possible ecological impacts of Bt on earwigs.
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Palavras-chave
Controle biológico, Entomopatógenos, Resposta funcional, Teias alimentares, Tesourinhas, Biological control, Entomopathogens, Functional responses, Earwigs, Food webs