ANTIBIOSIS IN Brachiaria jubata TO THE CERCOPIDS Zulia colombiana Lallemand AND Aenelamia reducta Lallemand

Abstract

Antibiosis and tolerance were detected in Brachiaria accessions screened for re­sistance to two spittlebug species (Cer­copidae). Mortality of nymphs of Zu­lia colombiana and Aeneolamia reduc­ta was higher on B. jubata CIAT 16531 and B. brizantha cv. Marandú compared with the susceptible B. de­cumbens cv. Basilisk and B. dictyo­neura cv. Llanero. Fourth and fifth instar nymphs transferred from cv. Lla­nero to B. jubata CIAT 16531 suffered high mortality equal to that of con­trols reared exclusively on B. jubata CIAT 16531 Fourth instar nymphs transferred from B. jubata CIAT 16531. to cv, Llanero experienced low mortality, equal to control on cv. Llanero. However, fifth instar nymphs transferred from B. jubata CIAT 16531 to cv. Llanero experien­ded high mortality, suggesting a criti­cal stage of susceptibility to the resis­tance factor present in B. jubata CIAT 16531 between fourth and fifth instars. Nymphs reared on B. jubata CIAT 16531 typically died during the lasa instar molt, often between apolysis and ecdysis, with abnormalities in the pharate adults.