Cmd. Dharmasena et al., Effect of storage on the efficacy of powdered leaves of Annona squamosa for the control of Callosobruchus maculatus on cowpeas (Vigna unguiculata), PHYTOPARASI, 29(3), 2001, pp. 191-196
Annona squamosa L. is widespread in Sri Lanka and its leaves are collected
by some farmers to protect their stored cowpeas from predation by bruchids.
Removal of the leaves during the dry season, when the farmers harvest thei
r cowpeas, can decrease the yield of A. squamosa fruit. This study investig
ated whether storing the leaves before they are used would reduce the insec
ticidal activity of the leaves, Overall, acetone and ethanol extracts made
from fresh and stored leaves of A. squamosa decreased the number of adult C
allosobruchus,maculatus (F.) emerging from cowpeas; however, in some bioass
ays the extracts from fresh leaves were more active than those from leaves
stored for 6 months. Acetone extracts from fresh and stored leaves were tox
ic to adult beetles, whereas the ethanol extracts were not active. Acetone
and ethanol extracts from fresh leaves had potent ovicidal activity when ap
plied to 2-day-old eggs.