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The Effect of Rainfall on the Cotton Jassid, Empoasca lybica (De Berg.) in the Gezira, Anglo-Egyptian Sudan

Published online by Cambridge University Press:  10 July 2009

A. D. Hanna
A. D. Hanna
Affiliation:
Senior Entomologist, Research Farm, Wad Medani.
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Extract

The Gezira Scheme is divided into three areas according to the incidence of the Cotton Jassid, Empoasca lybica.

1. The Northern area of normal abundance.

2. The Central area of occasional abundance.

3. The Southern area of possible abundance.

The causes for this difference in the number of Jassids in the three areas were studied and rainfall in showers over 10 mm. in July and August was found to be the important factor. A definite correlation was found between the number of Jassids on cotton and the amount of this rainfall.

Some experiments were carried out which proved that the effect of rain was due to the splashing of mud from the soil on to the lower side of the leaves. The rain could therefore be effective if it is heavy enough to produce mud splashing.

It was shown by a simple apparatus that mud splashing hardly rises more than 30–40 mm.

The correlation between the number of Jassids and the amount of rainfall in July and August might be used as a basis for forecasting the extent of Jassid attack on cotton every year.

Type
Original Articles
Information
Bulletin of Entomological Research , Volume 41 , Issue 2 , September 1950 , pp. 359 - 369
Copyright
Copyright © Cambridge University Press 1950

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References

Cowland, J. W. (1947). The Cotton Jassid (Empoasca libyca, Berg.) in the Anglo- Egyptian Sudan, and experiments on its control.—Bull. ent. Res., 38, pp. 99–115.CrossRefGoogle Scholar
Cowland, J. W. & Edwards, C. J. (1949). Control of Empoasca lybica de Berg. on Cotton in the Anglo-Egyptian Sudan.–Bull. ent. Res., 40, pp. 83–96, 1 pl. 3 figs.CrossRefGoogle Scholar
Uvarov, B. P. (1931). Insects and climate.—Trans. ent. Soc. Lond., 79, pp. 1–247.CrossRefGoogle Scholar