stock of grain decreases after seve

stock of grain decreases after several months as a result of
migration away from the store. Callosobruchus maculatus and
B. atrolineatus adults have been observed making massive flights
during the period when cowpea is maturing in the field; this
presumably results in bruchid eggs being laid on cowpea pods
(Monge and Huignard, 1991).
The lethal effects of B. senegalensis leaves on adults, larvae and
eggs of B. atrolineatus and C. maculatus have been well documented
(Alzouma and Boubacar, 1987; Douma and Alzouma, 2001; Seck
et al., 1993). The insecticidal activity of B. senegalensis results
from the release of methyl isothiocyanate (MITC) and methyl
cyanide (acetonitrile) after enzymatic degradation of glucopparin
in the leaves and fruits of the plant (Loignay et al., 1994). In the
current study, treatment of infested cowpea grain with fresh leaves
of B. senegalensis did not provide protection. In our experiments,
B. senegalensis was used at a dosage of 500 g of leaves and stems for
each 500 g of cowpea, well above the recommended dose of 2e4%
(Seck et al., 1993). This may perhaps be explained by the quality of
the leaves of B. senegalensis we used.