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SUSCEPTIBILITY OF IMMATURE STAGES OF MELANOPLUS SANGUINIPES (FAB.) (ORTHOPTERA: ACRIDIDAE) TO NOSEMA CUNEATUM HENRY (MICROSPORIDA: NOSEMATIDAE) AND ITS EFFECT ON HOST FECUNDITY1

  • M.A. Erlandson (a1), Al B. Ewen (a1), M.K. Mukerji (a1) and C. Gillott (a1)

Abstract

Second- 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.

Des larves de stades 2 et 3 de Melanoplus sanguinipes (Fab.) se sont avérées plus susceptibles au Nosema cuneatum Henry que des larves de 5ième stade. Les délais de mortalité étaient significativement plus courts dans le cas des larves des stades 2 et 3 inoculées avec 1.0 × 106 et 104 spores de N. cuneatum par individu, que des larves de 5ième stade traitées de la même façon, et un pourcentage plus élevé de ces dernières étaient restées saines à la fin de l’expérience (40–60 jours post-inoculation). Des larves de 5ième stade inoculées avec 1.0 × 106 spores par individu ont montré une longévité raccourcie. Le nombre d’oeufs pondus par femelle n’était pas significativement différent entre des criquets témoins et ceux traités au 5ième stade. Cependant le poids sec et le pourcentage d’éclosion des oeufs pondus par des criquets inoculés étaient significativement inférieurs à ceux mesurés chez des criquets sains. De 20% à 30% de la progéniture de criquets inoculés au stade 5 ont montré des niveaux sensibles de sporoblastes et de spores du N. cuneatum.

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References

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SUSCEPTIBILITY OF IMMATURE STAGES OF MELANOPLUS SANGUINIPES (FAB.) (ORTHOPTERA: ACRIDIDAE) TO NOSEMA CUNEATUM HENRY (MICROSPORIDA: NOSEMATIDAE) AND ITS EFFECT ON HOST FECUNDITY1

  • M.A. Erlandson (a1), Al B. Ewen (a1), M.K. Mukerji (a1) and C. Gillott (a1)

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