Effects of companion crops on population dynamics of maize lethal necrosis disease vectors in Bomet County, Kenya
Namikoye, E. S.
Kinyua, Z. M.
Githendu, M. W.
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Maize is the most consumed staple food crop in Kenya with a per capita of 110kg. It is equally an important commercial crop particularly in high potential areas. Currently, the presence of Maize lethal necrosis disease (MLND) has constrained its production. The disease is challenging to manage because it is a co-infection of maize by two viruses, the Maize chlorotic mottle virus and Sugarcane mosaic virus, which are vectored mainly by C0111 thrips iFrankliniella Williamsi) and C0111 leaf aphids (Rhopalosiphum maidis), respectively. This study was carried out to assess the potential for companion crops to act as traps or repellents for these vectors, thus contributing to vector management. Trials were carried out in fanners' fields in Bomet County. Treatments included Napier, coriander, millet, sorghum and maize, arranged in a randomized complete block design with four replicates for two seasons, November 2014- April 2015 and April-August 2015. Each crop was planted either as an intercrop or a border crop with maize as the main crop. We present results from the first season. There were significant differences (P<O.OO 1) in the presence of C0111 Thrips among the companion crops although intercrops (21. 53) recorded a slightly higher significant figure than border crops (10.28). Coriander trapped the highest number of C0111 thrips (27.6), followed by sorghum (22.2). Napier and millet trapped the lowest mean number of thrips, 9.1 and 4.7, respectively. However, in comparison with maize (85.96), companion crops had significantly lower C0111 thrips, Coriander hosted the highest number of aphids (132.6) compared with Napier (45.9) and sorghum (30.8) while millet recorded the lowest (5.6). The number of aphids in coriander and maize (60.4) was not significantly different from each other but was significantly higher compared with those registered in other companion crops (P=O.0021). This preliminary study shows that both Napier and millet may act as repellent crops for Com Thrips mainly as border crops while coriander and sorghum could act as trap crops majorly as intercrops.