Newbouldia laevis (Seem)‎ as an entomocide against sitophilus oryzae and sitophilus zeamais infesting maize grain

Abstract EN

This study was conducted under laboratory conditions at temperature of 28 ± 2oC and relative humidity 75 ± 5 % to investigate the entomocidal flurry of Newbouldia laevis against Sitophilus oryzae and Sitophilus zeamais infesting maize grain in storage.

The powders of stem and root of N.

laevis were prepared at 0.1, 0.2, 0.3, 0.4 and 0.5g dosages, while their extracts were prepared at 1, 2, 3, 4 and 5 % concentrations.

The control experiments were also set up.

None of the powders of stem and root of this plant was able to achieve complete mortality of the two insects within 96h of application, except for the root powder which was able to achieve 100 % mortality of S.

oryzae at 0.5g dosage only.

Only the root extract at 4 % was able to achieve complete weevils mortality within 96h and its effect was significantly different (p < 0.05) from the extracts of the stem except at 4 and 5 % concentration of stem extract.

The fiducial limits showed that a lower concentration of root extract was needed to cause 50 % mortality in S.

zeamais (0.00-1.64 %) when compared to the concentration needed for S.

oryzae (0.10-1.72 %).

Both the stem and root extracts of the plant were more effective than their powders.

The powders and the extracts of this plant either reduced or prevented the emergence of adult weevils and inhibit the developmental period of the insects.

The powders and the extracts of N.

laevis also reduced or prevented the weight loss of the treated maize grains.

Therefore, with the result obtained in this research, both the powder and extract of N.

laevis root and stem could go a long way in the quest of providing alternative wherewithal to the use of chemical insecticides for protecting maize grain in storage.

Root extract of N.

laevis could, however, offer more protection against S.

oryzae and S.

zeamais infesting maize grain than its stem extracts.