Potencial endofítico de fungos entomopatogênicos associados a Urochloa ruziziensis para controle de cigarrinhas-das-pastagens (Hemiptera: Cercopidae)

Abstract

Pasture spittlebugs are pests of forage crops in Tropical America, causing damage to forage crops, and promoting high annual losses in milk and meat production. Usually fought with defensive use of insecticide; such an alternative may result in environmental and economic impacts, requiring the removal of cattle from the pasture during its application. One of the alternatives for combatting these insect-pests is using entomopathogenic fungi that do not generate environmental impacts, in addition to not having to remove the herd from the pasture for its application. Therefore, the objectives of this research were: i - to evaluate the endophytic potential of entomopathogenic fungi applied to brachiaria, using seed treatment to control Mahanarva spectabilis (Distant) and Deois schach (F.) (Hemiptera: Cercopidae); ii - to analyze the efficiency of banker plants as a means of disseminating the fungus in the field and, iii - to determine the frequency of infection after storage of treated seeds. Brachiaria seeds were treated with a suspension, containing 1x108 for 30 minutes, of the fungi UFMG 11443, UFMG 11444, and Metarhizium anisopliae, were planted in 2L pots, and maintained in a greenhouse. The surplus of treated seeds was properly conditioned at 22 0C and sown monthly for 10 months. Nymphs of the pest-insects were fed on the plants from treated seeds. It was found that the entomopathogenic fungi were endophytic, infected equally the spittlebugs species M. spectabilis and D. schach at different developmental stages; however, they caused low nymphal mortality. The use of the banker plant technique containing plants from seeds treated with the entomopathogenic fungi was efficient. Furthermore, it was observed that it is possible to store the fungus-treated seeds for 12 months.