Population fluctuations of aphid pests of Chromolaena Odorata (Eupatorium Odoratum) in Kerala

Abstract

In studies on the population fluctuations of the aphidpesfsof Chromolaena odorata Linn, in the plains and medium hilly localities of Trichur district (Kerala State), it was found that Aphis spiraecola Patch and Aphis fabae Scopoli occurred at peak levels in July in both situations, the diversity of occurrence per unit area being also higher in July. Brachycaudus helichrysi KItb. occurred at higher elevations of the Idukki, Wynad districts causing complete damage to the plants. Nymphs and adults of A. spiraecola and A. fabae fed on tender leaves and shoots causing severe leaf crinkling. Consequent on feeding by B. helichrysi the leaves became rolled and the entire plants showed wilting symptoms. As candidates for the bio-control of C. odorata in Kerala, these aphids do not appear to be quite promising.