Incidence of maize mosaic virus and maize chlorotic mottle virus in corn, in relation to within-field activity of their vector insects in corn as influenced by sunn hemp intercropping

Field experiments were conducted to examine effects of sunn hemp, Crotolaria juncea L. intercropping on within field-activity of (i) corn planthoppers, Peregrinus maidis Ashmead and corn thrips, Frankliniella williamsi Hood, and (ii) incidence of Maize mosaic virus (MMV) and Maize chlorotic mottle virus (MCMV) symptomatic corn plants in corn – sunn hemp intercropping system. Within-field activity of macropterous P. maidis and adults of F. williamsi was quantified using trap catches as an activity measure. Results showed that sunn hemp intercropping significantly increased within-field activity of macropterous P. maidis and adults of F. williamsi compared to corn monoculture treatment. Increase in within-field activity of P. maidis in the intercropped treatment during vegetative stages of corn development coincided with reduced colonization, that might have reduced number of feeding vectors and plant tenure time, resulting lower incidence of MMV as compared to the monoculture, as the events required for persistent transmission of plant virus were disrupted. Increase in within-field activity of F. williamsi in the intercropped treatment suggested greater movement of vectors and contributed to higher incidence of MCMV compared to the monoculture treatment, as is characteristic of semi-persistent transmission of plant virus.