Occurrence of Entomophthorales on Spittlebugs Pests of Pasture in Eastern São Paulo State, Brazil

Abstract

Spittlebugs (Hemiptera: Cercopidae) are the most important pests of pasture in Brazil. Nymphal behavior, i.e. residing in the soil, makes their control with insecticides difficult. Although Entomophthorales fungi occasionally have been found at epizootic levels in spittlebug populations, they have not been cultured, had their incidence levels determined, nor evaluated for pest control potential. The research reported here aimed to evaluate the occurrence of Entomophthorales species on spittlebug pests of pasture in Pindamonhangaba County, São Paulo State, Brazil. Evaluations were carried out in 2 adjacent fields with Brachiaria decumbens and Pennisetum purpureum grasses, respectively, of 5 ha each. Evaluations were done every 4 days from January through February by capturing spittlebug adults on leaves with an entomological sweep net, and the insect samples were kept frozen until examined. Insect abdomens were dissected and observed by microscopy for the presence of hyphae and resting spores. Insects cadavers with sporulating fungus were collected in the field and taken immediately to the lab to isolate the pathogen. Scanning electron microscopy pictures were taken of conidophores, and primary and secondary conidia of both fungi. Furia sp. was found at epizootic levels on Deois schach in the Brachiaria pasture, reaching 80% infected followed by a fall in the insect population. Batkoa sp. was found at enzootic levels (< 10% infected) on Mahanarva fimbriolata in the P. purpureum pasture. Furia sp. also was found to infect another important spittlebug, Deois flavopicta, indicating that it has good potential as a bioinsecticide. Heavy rainfall adversely affected the occurrence of Batkoa sp. in M. fimbriolata populations in P. purpureum pasture.