Assessment of Insecticidal Activity of Sesame (Sesamum indicum L.) Leaf Aqueous Extract against the Cowpea Beetle Callosobruchus maculatus (Fabricius)

• H.E. Negbenebor

  Department of Biological Science, Baze University, Abuja, Nigeria.

  Author

• F.M. Mairami

  Department of Biological Science, Baze University, Abuja, Nigeria.

  Author

• A. Mijinyawa

  Department of Botany, Ahmadu Bello University, Zaria, Nigeria.

  Author

• S. Nura

  Department of Biology, Ahmadu Bello University, Zaria, Nigeria.

  Author

A research was conducted to assess the insecticidal activity of leaf aqueous extract of sesame (Sesamum indicum L.) against Callosobruchus maculatus infestation on stored cowpea seeds. Four different concentrations (1g/ml, 2g/ml, 3g/ml, and 4g/ml) were formed from sesame leaves and there was also a control treatment. Disinfected cowpea seeds were treated with the extracts thereafter, the seeds were infested with adult male and female C. maculatus. The experiment was laid down in a completely randomized design with each treatment and control replicated three times. Data collected on different parameters on the insect were subjected to analysis of variance and Duncan’s New Multiple Range test was used for separation of means. The toxicity of the extracts was also determined. The results from the studies showed that the effects of different concentrations of the aqueous extract on insects’ mortality, oviposition, progeny development and number of seeds damaged by the insects differs significantly (P≤0.05). The effect is concentration dependent, increased with an increase in concentration. The highest mortality rate was recorded in insects exposed to 4 g/ml of the extracts at both 24 h of exposure (1.67%) and 48 hours of exposure (3.00%). Similarly, no eggs were laid on 4 g/ml treated seeds. The extracts inhibited progeny development to the larval stage and reduced the percentage number of damaged seeds. A significant positive correlation (P≤0.05) was found between the rate of seeds damaged with an increased rate of oviposition and progeny development but negatively with the rate of mortality. The extracts contained nine (9) active phytochemicals that conferred such effects. Sesame leaf aqueous extract was found to show high insecticidal activity against C. maculatus. It is, therefore, recommended that a 4.00 g/ml concentration of Sesamun indicum leaf aqueous extract can be use for effective control of C. maculatus infestation on stored cowpea seeds.

1. H.E. Negbenebor, Department of Biological Science, Baze University, Abuja, Nigeria.

   Department of Biological Science, Baze University, Abuja, Nigeria.

2. F.M. Mairami, Department of Biological Science, Baze University, Abuja, Nigeria.

   Department of Biological Science, Baze University, Abuja, Nigeria.

3. A. Mijinyawa, Department of Botany, Ahmadu Bello University, Zaria, Nigeria.

   Department of Botany, Ahmadu Bello University, Zaria, Nigeria.

4. S. Nura, Department of Biology, Ahmadu Bello University, Zaria, Nigeria.

   Department of Biology, Ahmadu Bello University, Zaria, Nigeria.

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