Efficiency of Aphid and Thrips Vectors in Transmission of Maize Lethal Necrosis Viruses

Maize lethal necrosis disease occur in major growing regions of Kenya, causing losses of up to 100% estimated at 50 million US$ in 2014/15. The study was undertaken to evaluate the efficiency of thrips and aphids in transmission of maize lethal necrosis viruses. Maize seedlings were inoculated with adults and nymphs of Western flower thrip (Franklinella occidentalis), corn leaf aphids (Rhapolosiphum maidis) and Russian wheat aphid (Diuraphis noxia) carrying maize lethal necrosis viruses. Data collected included virus titre, disease incidence and severity and plant height. Area under disease progress curve (AUDPC) was calculated using the MLN severity data. Adults of R. maidis were the most efficient vector of Sugarcane mosaic virus (SCMV) but adults and nymphs of F. occidentalis did not transmit any of the maize lethal necrosis viruses. The highest titre of SCMV at 0.38 was noted in plants where adults of R. maidis were used to transmit viruses. Disease severity and AUDPC was highest at 44.4 % and 928.3 respectively in plants inoculated with viruses using adults of R. maidis. Inoculating maize plants with viruses using R. maidis reduced plant height by 15.1 to 18.2%. The study showed that adults of R. maidis are the most efficient in transmission of Sugarcane mosaic virus. Therefore, for effective management of maize lethal necrosis disease, management of aphid vectors is critical.