D3421: Effects of plant growth characteristics and chemical composition on the relative suitability of edible amaranth varieties as hosts for major insect pests

Leafy vegetable crops, such as edible amaranths (Amaranthus spp.), have the potential to contribute significantly towards global food security. Edible amaranths also possess medicinal properties, and some species may be used in the production of various materials including wool and other fabrics. The production of this vegetable, however, is hampered by the activity of insect pests, chiefly, flea beetles and leafhoppers. The objectives of this study were to (a) identify non-preferred hosts for incorporation into Integrated Pest Management (IPM) programs, (b) describe growth characteristics of amaranth varieties, and (c) identify chemical constituents that may be responsible for differences in the suitability of amaranths as hosts for major insects. Five varieties of edible amaranths were used in a field experiment that was set up as a randomized complete block design. Pest density was estimated using visual sampling and yellow sticky card techniques. Data obtained from the study was analyzed using SAS statistical software. Significant differences in insect pest densities were found amongst the varieties. Strong correlations between starch content and insect pest populations were recorded. Results suggest significant effects of glucosinolate content of amaranths on their suitability as hosts for leafhoppers.