Transmission pattern of Maize chlorotic mottle virus (Machlomovirus) on maize by Frankliniella williamsi and F. occidentalis (Thripidae) in Kenya

Maize chlorotic mottle virus (MCMV) infects maize (Zea mays L) which is a major staple food crop in sub-Saharan Africa, causing yield losses of between 10-15%. When the virus co-infects with maize infecting potyviruses, they cause Maize lethal necrosis (MLN) disease which reduces yields by 30-100%. Persistence and efficiency transmission of MCMV by Frankliniella williamsi (Hood) and F. occidentalis (Pergande) was investigated. Transmission efficiency was evaluated at 1, 3, 24 and 48 hour inoculation access periods (IAPs). Virus post acquisition retention period was tested after 1, 2, 3, and 4 days on maize seedlings. Persistence transmission and rates of new re-infections (4, daily cycle) was determined. Plants were covered by nylon-mesh cages inside a greenhouse for symptom observation. Severity was measured and MCMV detected in leaf samples by ELISA and PCR. Means of infected plants at IAPs were log transformed (base 10) and a t-test done. Means of re-infected plants at retention periods were subjected to ANOVA. MCMV transmission rate of F. occidentalis rose while that of F. williamsi declined after 24 hour IAP. Means of infected plants by both thrips were significantly different (t = 2.77, D.F. = 362.97, P = 0.006). F. occidentalis infected plants had higher symptom severity than those by F. williamsi (0.2702, 0.1997), with 1.176 mean difference (was higher by 17.6 %). Plants re-infected by both thrips were significantly different (F = 10.27, D.F. = 2, 17, P = 0.001). F. occidentalis re-infected more plants than F. williamsi (0.32 ± 0.04, 0.27 ± 0.04) at 0.125 LSD. Inoculated plants by F. williamsi after day 1 post acquisition period were significantly different from those by F. occidentalis (F = 5.66, D.F. = 2, 17, P = 0.013). Both thrips transmitted MCMV in a non-persistent pattern and thus should be targeted in IPM strategies for MCMV control.