Abstract:
Methanol extracts of eighteen plants belonging to thirteen families were
evaluated under laboratory conditions for their effects on the oviposition and
larval mortality of the rice moth, Corcyra cephalonica. Each plant extract
was tested at a concentration of 12g11.All the extracts tested showed significant
variations in toxic and oviposition deterrence against C. cephalonica when
compared with the control. However, among the eighteen plants evaluated,
leaf and seed extracts of Azadiracta indica and the seed extract of Piper
nigrum were found to be the most effective causing 100% larval mortality.
This was followed by leaf (81 %) and seed (84%) extracts of Annona
squamosa. Conversely, the seed extract of Annona muricata was the least
toxic exhibiting only 2.83 % mortality. More over, maximum ovipostion
deterrence was observed with P nigrum followed by A. indica and A.
squamosa. None of the plant extracts had any adverse effects on the viability
of maize seeds. When percentage mortality and ovipositional deterrence were
considered as indices of insecticidal activity, P. nigrum and A. indica together
with A. squamosa proved to be the most effective plant materials that could
be used as grain protectants in controlling infestations of C. cephalonica.
