Response of lesser grain borer, Rhizopertha dominica (Fabr.)‎ [Coleoptera : Bostrichidae] to powders and extracts of Azadirachta indica and Piper guineense seeds

Abstract EN

The powders and extracts of Azadirachta indica A.

Juss and Piper guineense (Schum and Thonn) seeds were bioassayed for their insecticidal potential against the lesser grain borer, Rhizopertha dominica (Fabr.) in the laboratory at 30+2°C and 70+5 % relative humidity.

The powders were applied at rates 0.5, 1.0, 2.0 and 4.0g / 20g of wheat grains.

The extracts of the plants were also applied at rates 1, 2, 3 and 4 % / 20g of wheat grains.

The parameter studies were adult mortality, adult emergence, % reduction of adult emergence and weight loss in treated wheat grains.

The results obtained shows that adult mortality of R.

dominica increased as concentration of powders and extracts increased.

The two plants powders were able to evoked 100 % mortality of adult R.

dominica at rates 1.0, 2.0 and 4.0g / 20g of wheat grains after 72 hours of post treatment.

Adult emergence shows that more adult emerged from the control (46) which was significantly higher (P < 0.05) than others.

The extracts from the two plants seeds tested against R.

dominica were able to caused 100 % mortality of lesser grain borer within 48 hours of post treatment at all tested concentrations.

There was no adult emergence of R.

dominica in wheat treated with extracts compared to control (treated with solvent) which recorded 19 adult emergence and control (without solvent) which had 43 adult emergence.

The extracts did not affect the weight of treated wheat grains.

The results obtained from this, study justified that powders and extracts of A.

indica and P.

guineense seeds can be used as biopesticides against R.

dominica.

The two plants are of medicinal values, biodegradable, readily available and poses no danger to man and other mammals.