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Soil Conditions in Oviposition Sites of Zonocerus variegatus (L.) in Cassava Plots in a Sub-Humid Tropical Environment

Published online by Cambridge University Press:  19 September 2011

G. F. Tamu*
Affiliation:
Department of Zoology, University of Ibadan, Nigeria
W. W. D. Modder
Affiliation:
Department of Zoology, University of Ibadan, Nigeria
*
Corresponding author: GFT.
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Abstract

The temperature, pH, moisture, carbon and nitrogen contents of soils at oviposition sites of Zonocerus variegatus (L.) (Orthoptera: Pyrgomorphidae) located around cassava farms at Aiyepe, southwestern Nigeria, were compared with those of soils at non-oviposition sites (control) during different months. Although oviposition site soils did not differ in particle composition from control soils, their temperatures were, generally, significantly lower. Soils at oviposition sites lost significantly less organic carbon to oxidation and nitrogen to leaching. They also contained significantly more moisture than soils at control sites during February-April when oviposition occurred and newly deposited eggs, lacking the serosal cuticle, would be prone to desiccation in dry soils. Conditions at oviposition sites are a key factor in the selection of egg deposition by gravid Z. variegatus.

Résumé

La température, le PH, le taux d'humidité, le carbone et la teneur en azote ont étaient mesurés dans les sols aux sites de ponte de Zonocerus variegatus (L.) (Orthoptère: Pyrgomorphidae). Ces sites étaient localisés près des champs de manioc à Aiyepe, au sud-oeust du Nigeria et leurs sols ont été comparés aux sols en dehors des sites de ponte (témoin), au cours des mois différentes. Même si les sols sur les sites de ponte n'ont pas différé des sols témoins de part leur composition granulométrique, leurs températures étaient en général significativement basses. Les sols sur les sites de ponte perdaient moins de carbone organique dans le processus d'oxydation et moins d'azote dû au lessivage. L'humidité dans les sols des sites de ponte était plus élevée que celle dans les sols des sites témoins de fevrier à avril, les mois pendant lesquels la ponte avait lieu et où les oeufs pondus dans des sols secs étaient condamnés à la dessication suite au non-revêtement de cuticle séreuse. Les conditions prévalentes sur les sites de ponte constituent un facteur déterminant dans le choîx du lieu de ponte par les femelles gravides.

Type
Research Articles
Copyright
Copyright © ICIPE 1997

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