Neya B. James, Zida P. Elisabeth and Traore Oumar
Plants from seeds infected by Cowpea aphid borne mosaic virus (CABMV) are the only source of primary infections while aphid vectors are responsible for secondary infections. The effect of insecticide treatments against aphids and the quality of seeds on CABMV epidemics was investigated. Eight cowpea varieties were grown from virus-free seeds and also from seeds contaminated by the virus at three different rates. Disease incidence was recorded weekly during seven weeks and populations of aphids were also evaluated. Likewise, aphid’s population was evaluated 30 days after sowing and a “decis-systhoate” treatment was applied. The experiment was repeated for three consecutive years (2009-2011). For each year, the results showed no significant difference between the average numbers of insects per plot. The insecticide treatment showed negative and positive impact as the number of diseased plants in average increased in some plots and decreased in others. In 2011, year of severe epidemic, the reduction rates of sick plants in treated plots varied from 1 to 16% for varieties with weak transmission power of the virus by seed and from 6 to 52% for varieties with strong transmission power of the virus by seed. In conclusion, the insecticide treatment leads to a diminution of CABMV epidemics with the two groups of varieties in the treated plots.
