Virulência de Beauveria bassiana e Cordyceps javanica nos diferentes estágios de desenvolvimento de Duponchela fovealis e caracterização do processo de infecção

Orientadora: Profª Drª Ida Chapaval Pimentel.Coorientadora: Profª Drª Maria Aparecida Cassilha Zawadneak.Dissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Microbiologia, Parasitologia e Patologia. Defesa : Curitiba, 29/03/19.Inclui referências: p. 56-65.Resumo:Abstract:Resumo: A lagarta-da-coroa, Duponchelia fovealis Zeller (Lepidoptera: Crambidae) é uma espécie-praga de microlepidóptero que ataca folhas, flores, frutos e a coroa do morangueiro. É uma espécie exótica, recentemente descrita no Brasil, sem princípios ativos autorizados para o seu controle no país. Os fungos entomopatogênicos (EPF) constituem, no âmbito do Manejo Integrado de Pragas (MIP) uma alternativa de controle biológico desta praga. O presente estudo buscou avaliar o potencial de controle in vitro dos EPF Beauveria bassiana (Bea 111) e Cordyceps javanica (Isa 340) nos diferentes estágios de desenvolvimento de D. fovealis e registrar etapas de infecção por estes fungos no inseto por meio de Microscopia Eletrônica de Varredura (MEV). Para isso, foi avaliada a mortalidade entre os estágios variando as concentrações dos entomopatógenos, de 103 a 109 conídios.mL-1. Observou-se que, ovos são pouco afetados pelos fungos. No estágio larval a mortalidade aumenta gradativamente com o aumento na concentração de conídios por suspensão e reduz nos ínstares finais. As concentrações de 108 e 109 conídios.mL-1, nos primeiros ínstares larvais, apresentaram mortalidade de 100 e 94% e CL50 entre 105 e 107 conídios.mL- 1 para Bea 111 e Isa 340, respectivamente. O Tempo de Letalidade de 50 % (TL50) necessário dos isolados contra os ínstares iniciais, nas concentrações mais altas é de 40,35 horas para Bea 111 e 45,55 para Isa 340. O estágio de pupa, apresentou na concentração de 109 conídios.mL-1 porcentagem de viabilidade pupal entre 60 e 80 % utilizando-se Isa 340 e Bea 111, respectivamente. Através da MEV foi possível registrar o início da penetração do EPF na cutícula larval 6h após a inoculação e a extrusão fúngica entre 54 e 94 h após a aplicação, com evidente formação de estruturas reprodutivas em insetos inoculados com Bea 111. Nossos resultados positivos em relação ao biocontrole de D. fovealis in vitro por B. bassiana e C. javanica sugerem seu potencial de uso no campo.Abstract: The European Pepper Moth, Duponchelia fovealis Zeller (Lepidoptera: Crambidae) is amicrolepidopteran pest species that attacks leaves, flowers, fruits and the crown of the strawberry. It is an exotic species, recently described in Brazil, with no active principles authorized for its control in the country. In the context of Integrated Pest Management (IPM), entomopathogenic fungi (EPF) are an alternative for the biological control of this pest. The present study aimed to evaluate the in vitro control potential of EPF Beauveria bassiana (Bea 111) and Cordyceps javanica (Isa 340) in the different stages of development of D. fovealis and to register stages of infection by these fungi in the insect by means of Electron Microscopy (SEM). For this, the mortality between the stages was evaluated, varying the entomopathogen concentrations, from 103 to109 conidia.mL-1. It was observed that eggs are poorly affected by fungi. In the larval stage mortality increases gradually with the increase in conidia concentration per suspension and reduces in the final instars. The concentrations of 108 and 109 conidia.mL-1 in the first larval instars presented 100% and 94% mortality and LC50 between 105 and 107 conidia.mL-1 for Bea 111 and Isa 340, respectively. The required 50% Lethality Time (LT50) of the isolates against the early instars, at the highest concentrations is 40.35 hours for Bea 111 and 45.55 for Isa 340.The pupal stage presents in the concentration of 109 conidia.mL-1 percentage of pupal viability between 60 and 80% using Isa 340 and Bea 111, respectively. Through the SEM it was possible to record the beginning of the penetration of the EPF in the larval cuticle 6h after inoculation and the fungal extrusion between 54 and 94 h after application, with evident formation of reproductive structures in insects inoculated with Bea 111.Our positive results regarding the biocontrol of D. fovealis in vitro by B. bassiana and C. javanica suggest its potential for use in the field

Infection of Beauveria bassiana and Cordyceps javanica on different immature stages of Duponchelia fovealis Zeller (Lepidoptera: Crambidae)

31 Pags.- 2 Tabl.- 6 Figs. The definitive version is available at: https://www.sciencedirect.com/science/journal/02612194Entomopathogenic fungi (EPF) can be viable options for biological control of agricultural pests. The selection of fungal strains is crucial for a successful pest control. The current study aimed to determine in the laboratory the susceptibility of different immature stages of Duponchelia fovealis Zeller (Lepidoptera: Crambidae) to EPF strains (Beauveria bassiana Bea111 and Cordyceps javanica Isa340). Immature stages of D. fovealis were sprayed with EPF concentrations from 2 × 103 to 2 × 109 conidia mL−1 and their viability and mortality were evaluated. Lethal time and concentration were estimated for pupae and each larval instar. Virulence depended on strain, dose, and insect life stage. The eggs were resistant to Bea111 and Isa340 strains. Mortality of larvae depended on the EPF strain and the larval instar, with the first instar being the most sensitive. Lethal concentrations for D. fovealis 1st instar larvae were 3.4 × 105 and 1.7 × 107 conidia mL−1 with Bea111 and Isa340, respectively. Isa340 performed better than Bea111 for controlling pupae. Scanning electron microscopy revealed the adhesion and penetration structures of both fungi in the 2nd instar infected larvae 6 h after inoculation, while fungal extrusion occurred between 54 and 94 h after spraying with Bea111 and Isa340, respectively.This work was supported by Coordination for the Improvement of Higher Education Personnel (CAPES) [grant numbers 1726812 and 1771724], and National Council for Scientific and Technological Development (CNPq) [grant number 403266/2013–0].Peer reviewe