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PARASITISM BY SCELIO CALOPTENI RILEY (HYMENOPTERA: SCELIONIDAE) IN EGGS OF THE TWO DOMINANT MELANOPLINE SPECIES (ORTHOPTERA: ACRIDIDAE) IN SASKATCHEWAN1

Published online by Cambridge University Press:  31 May 2012

M.K. Mukerji
M.K. Mukerji
Affiliation:
Agriculture Canada Research Station, 107 Science Crescent, Saskatoon, Saskatchewan, Canada S7N 0X2
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Abstract

Parasitism by Scelio calopteni Riley in eggs of Melanoplus bivittatus (Say) and M. sanguinipes (Fabr.) in Saskatchewan during 1967–1980 was highly aggregated. There was no evidence of any numerical response of the parasites to adult grasshopper density and, furthermore, change in grasshopper population density was independent of percentage parasitism. Thus, it is concluded that parasitism by S. calopteni does not play a significant role in the population dynamics of the two grasshopper species. The relationship between parasitism and wetness in August was highly significant in both grasshopper species and showed that percentage parasitism increased, but at a decreasing rate, up to a certain wetness and levelled off thereafter.

Résumé

Le parasitisme exercé par Scelio calopteni sur les oeufs de Melanoplus bivittatus (Say) et de M. sanguinipes (Fabr.) en Saskatchewan de 1967 à 1980 est fortement groupé. Il n’existe aucune preuve de réaction numérique des parasites à la densité de population des criquets adultes et, bien plus, la variation de densité de population des criquets est indépendante du taux de parasitisme. L’auteur conclut donc que le parasitisme exercé par S. calopteni ne joue pas un rôle important dans la dynamique des populations des deux espèces de criquets. Le rapport entre le parasitisme et le temps pluvieux en août est très significatif sur les deux espèces de criquets et révèle que le taux de parasitisme augmente, mais à un rythme décroissant, jusqu’à un certain degré d’humidité, pour ensuite plafonner.

Type
Articles
Information
The Canadian Entomologist , Volume 119 , Issue 2 , February 1987 , pp. 147 - 151
Copyright
Copyright © Entomological Society of Canada 1987

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