SUSCEPTIBILITY OF IMMATURE STAGES OF MELANOPLUS SANGUINIPES (FAB.) (ORTHOPTERA: ACRIDIDAE) TO NOSEMA CUNEATUM HENRY (MICROSPORIDA: NOSEMATIDAE) AND ITS EFFECT ON HOST FECUNDITY

Abstract

AbstractSecond- and 3rd-instar nymphs of Melanoplus sanguinipes (Fab.) were more susceptible to Nosema cuneatum Henry infection than were 5th-instar nymphs. Lethal times were significantly lower for 2nd- and 3rd-instar nymphs inoculated with 1.0 × 106 and 104N. cuneatum spores/individual than for similarly treated 5th-instar nymphs and a much higher percentage of the latter were uninfected at the end of the experimental period (40–60 days post-inoculation). Fifth-instar nymphs inoculated with 1.0 × 106 spores/individual showed reduced adult longevity. The number of eggs laid per female was not significantly different for inoculated or untreated 5th-instar nymphs. However, the dry weights of eggs laid by inoculated grasshoppers were significantly lower and fewer eggs hatched than for those laid by untreated grasshoppers. Twenty to 30% of the progeny from inoculated 5th-instar nymphs had detectable levels of N. cuneatum sporoblasts and spores.