Production of conidia by entomopathogenic isolates of Fusarium caatingaense on different vegetable substrates
2021
de Lima, Isabela Janne | Carneiro Leão, Mariele Porto | da Silva Santos, Ana Carla | da Costa, Antônio Felix | Tiago, Patricia Vieira
The cactus Opuntia ficus-indica (L.) Miller, used as the principal food source for livestock in arid and semi-arid regions of Brazil, is being threatened by cochineal scale, Dactylopius opuntiae Cockerell. The potential of entomopathogenic isolates of Fusarium caatingaense Santos, Lima, Tiago & Oliveira to control this pest has been reported. The objective of this study was to select suitable substrates for the production of conidia by F. caatingaense isolates, while maintaining their viability and pathogenicity against the insect. Five F. caatingaense isolates obtained from D. opuntiae were grown on 11 substrates: rice grains, rice grains + peptone, cracked corn, cracked corn + peptone, cracked corn + yeast extract, cactus flour, cactus flour + peptone, wheat bran, wheat bran + peptone, castor bean meal, and castor bean meal + peptone. The production and viability of conidia of the F. caatingaense isolates varied among the vegetable substrates studied. Rice grains, cracked corn and wheat bran, with or without supplementation, were the best substrates, especially for the URM 6779 and URM 6782 isolates. The URM 6779 isolate was selected for sporulation, germination and pathogenicity analysis after storage in rice at different temperatures (4 and 28 °C) and time periods (0, 15, 30, 60 and 90 days). Storage at 4 °C was the most suitable for mass production of this fungus because it maintained good rates of production and germination of conidia, and mortality against D. opuntiae until the 90th day of storage.
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