Impacts of balanced nutrient management systems technologies in the northern Guinea savanna of Nigeria

Mulching is common practice in the field production of vegetables. The aim of this study was to investigate the effect of polyethylene mulches (black, brown, clear, green, white) on single aphid species in a watermelon field. Aphids were sampled weekly using yellow water traps. During two spring seasons we detected a total of 70 species in 48 genera, of which 33 species which represented more than 5% of the total per catch were analysed for mulch colour attractiveness in each season. Among them 13 aphid species in 2004 and 16 in 2005 showed a response to the colour of the plastic mulch at least once in six samplings. Different response to mulch colour considering overall seasonal number was found for 15 species in both years. The four most economically important aphid species which transfer cucurbit viruses, Acyrtosiphon pisum (Harris), Aphis craccivora Koch, Aphis gossypii Glover and Myzus persicae (Sulzer), expressed different responses to mulch colour. Generally, A. pisum was of low abundance on brown mulch, M. persicae was less attracted to black, brown and clear mulches. The cowpea aphid A. craccivora was less attracted to black mulch. The abundance of A. gossypii was low in traps over clear mulch at two sampling dates and as overall seasonal number in 2004, the same was true on two of four samplings and as overall seasonal aphid number in 2005. Our results demonstrated that mulch colour not only affects the total number of aphids which populate crops, but also the presence of individual species may depend on mulch colour depending on sampling date and season. The presented species are mostly polyphagous and their preference for certain mulches can be used in crop protection management.