Farmers knowledge and control of two major pests: Helicoverpa armigera (Hübner) (Lepidoptera, Noctuidae) and Aphis gossypii (Glover) (Homoptera: Aphididae) in five agroecological zones in Benin (West Africa)

A survey study was performed in five agro-ecological zones in Benin to assess farmers’ knowledge and perceptionon the identification, damage recognition, applied control methods of two cotton insect pests Helicoverpaarmigera Hübner and Aphis gossypii Glover. A total of 200 farmers were interviewed in the five agroecologicalzones in Benin, using semi-structured questionnaire interviews. Results revealed sound knowledge of farmers onthe identity of H. armigera and A. gossypii. Farmers easily recognized H. armigera through its damage ondifferent plant organs while A. gossypii was known only at high infestation stage. Moreover, many crops arelisted as host plants for H. armigera and A. gossypii with different economic injuries. Control of these insectpests was done mainly by the use of chemicals with various application numbers and frequencies. The mostapplied chemicals for the control of H. armigera on cotton were Nurelle D 236 EC in zone 4 and 6, Thunder145O-Teq in zone 5 and Tihan 175 O-Teq in zone 2, while protection against A. gossypii was done using mostly Thian175 O-Teq except in the zone 6 where Fanga was used. The time interval between two treatments was 3-14 daysdepending on the product in use, the target insect and the agro-ecological zone. The effectiveness of the differentproducts was diversely appreciated. Farmers claimed to be aware of the so many side effects of chemicalsapplication. In organic cotton area, alternative method consisting of the use of botanical extracts was beingexperimented

Influence of cotton plant on development of Aphis gossypii Glover (Homoptera: Aphididae)

Aphis gossypii Glover (Homoptera: Aphididae) is one of the most important cotton pest in Benin. Experiments were carried out to determine population growth parameters of this pest and to compare its performance when feeding on detached leaves as opposed to the whole plant at constant temperature of 27 ± 1°C and 70 ± 5% of relative humidity. Results indicate that A. gossypii developed through four development stages with a mean development cycle of 4.38 ± 0.067 days. The doubling time of the aphid population was higher on whole plants (2.25 ± 0.02 days) than on detached leaves (1.91 ± 0.02 days). Similarly, the reproduction rate (Ro) of A. gossypii was lower on whole plants (16.023 ± 1.32) than on detached leaves (33.35 ± 1.68). Development, survivorship and reproduction of the aphid were negatively impacted by whole cotton plants, suggesting the possible induction of defence mechanisms