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.
