Behavioural Responses of Cowpea Bruchid to Three Volatile Organic Compounds from Cowpea

• B.I. Temisan

  Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

  Author

• E.A. Oyeniyi

  Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

  Author

• J.A. Adeyemi

  Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

  Author

• O.E. Oladipo

  Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

  Author

Investigation was conducted to evaluate the behavioural responses of adult Callosobruchus maculatus (F.) to three volatile organic compounds (VOCs) (oleic acid, β-pinene, and p-xylene) at four mixed ratios (1:1:1, 1:2:1, 2:1:1, 1:1:2) and at different concentration (0.1, 0.2 and 0.3 µg g⁻1). The attraction of both sexes to different concentration of oleic acid and p-xylene, oleic acid and β-pinene, and β-pinene and p-xylene were also investigated. Test odorant (VOC sample) and solvent (blank control) were separately applied to cotton wool and placed in each arm of the Y-tube olfactometer. Individual bruchid was introduced at the base of the olfactometer and given 15 minutes to choose an arm. Various results showed that the three compounds significantly (p < 0.05) attracted unsexed adult bruchids relative to control, and the percentage attraction ranged from 80.00 to 95.00%, irrespective of the VOCs. Similarly, VOC type, experimental concentration and sex significantly influenced the percentage attraction of adult bruchids relative to the control. However, only the two-way interaction of VOCs with concentration (VOC*C) significantly influenced the attraction of adult bruchids to VOCs. Relative to controls, β-pinene and p-xylene significantly attracted the highest (36-38) and lowest (32-35) number of bruchids. Female bruchids were significantly attracted to β-pinene at 0.3 and 0.1 µg g⁻1 relative to p-xylene. All the four mixed ratios exhibited greater attraction compared to the individual compounds irrespective of the concentration. However, the highest (39) (97.5%) attracted bruchid was caused by 1:1:2 mixed ratio of oleic acid, β-pinene and p-xylene compounds at all the three concentrations relative to blank control. This study revealed that β-pinene and the mixed ratio of 1:1:2 caused the highest attraction of adult C. maculatus. Therefore, it could serve as excellent lures for baited traps for effective monitoring and management of cowpea bruchids infesting cowpea in the field and storage.

1. B.I. Temisan, Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

   Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

2. E.A. Oyeniyi, Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

   Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

3. J.A. Adeyemi, Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

   Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

4. O.E. Oladipo, Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

   Department of Biology, School of Life Sciences, Federal University of Technology, P.M.B.704, Akure, Ondo State, Nigeria.

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