Diapause and quiescence in eggs of a tropical grasshopper Oedaleus senegalensis (Krauss)
1996
Gehrken, U. | Doumbia, Y.O.
In Mali, eggs of the grasshopper Oedaleus senegalensis enter diapause at the end of September and remain in diapause for 7-8 months; thereafter eggs are in a state of quiescence until they are exposed to moist conditions. The developmental arrest supervenes at an anatreptic stage characterized by the appendages being turned inward and downward. Diapause termination began in April, and 80% of the pods had resumed development by the end of May. Eggs from individual pods developed simultaneously, and approximately 10% were either infertile or had died during development. The eggs possibly absorb water vapor directly from atmospheric air, and soil moisture as low as 1% was adequate water for stimulating the egg hatch. Tolerance to water loss was apparently linked to the anatreptic stage; severe drought at other stages of development proved lethal. Diapause favors water conservation. At 5% RH, the water content was reduced by only 10% during 11 weeks in diapause eggs while nondiapause eggs died within 6 weeks after losing about 70% of their water content. At RH ranging from 27 to 62%, death from desiccation in postdiapause, quiescent eggs increased to 50 and 100% respectively in 3 and 16 months after diapause termination.
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