THE ABILITY OF APHIS-CRACCIVORA, A-GOSSYPII AND A-CITRICOLA TO TRANSMIT SINGLE AND MIXED VIRUSES TO COWPEAS

The ability of populations of adult apterous Aphis craccivora, A. goss ypii and A. citricola to transmit the cowpea aphid-bome virus (CAMV) a nd cucumber mosaic virus (CMV) to cowpea was investigated. CMV was mor e readily transmitted than CAMV by all three aphid species, but was mo st readily transmitted by A. craccivora and A. citricola, with transmi ssions ranging from 64-71 %. With CAMV, the infection level with A. go ssypii was higher than with A. craccivora and both were more efficient than A. citricola, although the differences were not significant. Wit h mixed infections of CAMV and CMV, there was a higher level of CAMV t ransmission using A. craccivora from sequential feeding when CMV-infec ted plants were fed on first followed by CAMV-infected plants, suggest ing that cowpea plants were more prone to infection by CAMV when alrea dy infected by CMV.