Development of drying methods and evaluation of blastospores efficacy of Beauveria bassiana, Cordyceps fumosorosea, and Metarhizium rileyi against Euschistus heros and Spodoptera spp.

• Ano de defesa: 2020
• Autor(a) principal: Corrêa, Bianca
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Controle microbiano; Fermentação líquida; Hypocreales; Liquid fermentation; Microbial control; Pragas da soja; Soybean pests
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/11/11146/tde-12012021-162749/

Blastospores are cells naturally produced inside the insect\'s body during the infection process by many entomopathogenic fungi. These cells can be produced in vitro in rich liquid media under proper agitation and aeration conditions. In Brazil, there is still no biopesticide based in blastospore being commercialized, all products based on aerial conidia. Beauveria bassiana and Cordyceps fumosorosea are known for their capacity to infect a broad range of hosts, while Metarhizium rileyi is well known for its specificity caterpillar. The soybean crop is responsible for more than half of the pesticides used in the country for pest control, whether by sucking insects or defoliating caterpillars. This study\'s objective was to select isolates of B. bassiana, C. fumosorosea, and M. rileyi with high productivity of virulent blastospores to a wide range of hosts and to develop drying methods for these cells, crucial steps for the development of a blastospore-based bioproduct. The first part of this project consisted of evaluating the blastospore production of 12 isolates of the fungi, B. bassiana (4), C. fumosorosea (4), and M. rileyi (4). Later, two isolates of each species were selected for the virulence assays with second instar caterpillars of Spodoptera cosmioides, Spodoptera eridania, Spodoptera frugiperda, and Euschistus heros adults. The second part of the project consisted of performing screening of fillers and formulations with three blastospore drying methods for C. fumosorosea, referred to as fast air drying, slow air, and spray drying. After selecting two formulations, the dried blastospores\' shelf life was determined for B. bassiana, C. fumosorosea, and M. rileyi stored at 4 and 28°C. The results showed that all the isolates attained concentrations upper 108 blastospores mL-1 and some reached higher than 109 blastospores mL-1. Significant variability was observed in pest species\' susceptibility to blastospores from isolates of the three fungal species. Blastospores were more sensitive to the drying process via spray drying, for some formulations and especially for M. rileyi. Two formulations F12 and F20 showed blastospores\' viability greater than 80% in the three drying methods. After 120 days of storage at 4°C, some combinations of formulations and drying methods showed blastospores viability above 70% for B. bassiana and C. fumosorosea. The results obtained in this project reveal the potential of using blastospores to control soybean pests and bring advances in the development of drying methods for these fungal structures.