Journal Of Tropical Biosciences
Volume No: 11|
Page No: 36
| FullText PDF
Title: TOXICITY OF SEED POWDER AND EXTRACTS OF JATROPHA CURCAS TO THREE STORAGE BEETLES
NEGBENEBOR*1, H. E, MAKANJUOLA2, W. A., DENLOYE3, A. A
1DEPARTMENT OF COMPUTING AND APPLIED SCIENCE,
BAZE UNIVERSITY, PLOT 686, CADASTRAL ZONE, ABUJA, NIGERIA.
2DEPARTMENT OF ZOOLOGY, UNIVERSITY OF LAGOS, AKOKA, LAGOS.
3DEPARTMENT OF ZOOLOGY AND ENVIRONMENTAL BIOLOGY,
LAGOS STATE UNIVERSITY, BADAGRY EXPRESSWAY, OJO, LAGOS.
Natural plant products may provide sustainable, safe, available and cheap alternative to synthetic insecticides in the control of storage insect pests threatening stored grains. As part of a search for such plant products, Jatropha curcas seed powder, ethanolic and oil extracts were screened for insecticidal potency against Callosobruchus maculatus F. (Bruchidae), Rhizopertha dominica F. (Bostrichidae) and Sitophilus zeamais Motsch (Curculionidae). Graded concentrations of each formulation were used as replicated treatments in exposure chambers of each test insect species in standard laboratory bioassays under ambient conditions. Insect mortality taken as quantal responses was used to compute median lethal concentration (LC50) values using probit analysis. Results showed that all formulations tested gave appreciable toxicity against each test insect species. The computed LC50 values showed that the powder was significantly more toxic (p< 0.05) to C. maculatus (2.00 g/kg) than either S. zeamais (5.30 g/kg) or R. dominica (8.87 g/kg). Similarly, the ethanolic extract was more toxic against C. maculatus (0.15 ml/L) than either S. zeamais (0.31 ml/L) or R. dominica (0.52 ml/L). The toxicity of test oil against each insect exposed was high (0.13 – 0.21 ml/L) but not significantly different from each other. The GC-MS analysis of the test ethanol extract showed that the major constituents are 9,-12, - Octadecadienoic acid ([Z, Z] (48.1%), benzene benzoate (0.3%) and squalene (0.14%). The study demonstrates the potential of J. curcas seed for use in the control of the three test insects.
The insecticidal activity of J. curcas extracts against S. zeamais, R. dominica and C. maculatus, indicate the potential for using them as natural sources of insecticidal material. The potential of using botanical products as alternatives to synthetic chemical forcontrol of S. zeamais, R. dominica and C. maculatus cannot be overemphasized. Botanicals will likely minimize cost and the negative impact of synthetic insecticide within the environment and to human health. The use of these test plants can be integrated into other environmentally friendly methods to achieve a good enough control as against using the hazardous synthetic insecticide. The identification of the active compounds and their modes of action against insect pest would contribute a lot to the development of synthetic pesticides, pest-management and also play a great role in the economic development of a given country.