Division of Agricultural Innovation and Management, Faculty of Natural Resources, Prince of Songkla University, Prince of Songkla University

Mealworm, Tenebrio molitor L. (Coleoptera: Tenebrionidae) is an important economic insect in southern Thailand. Waste of insects in farming process is frass or excrement which can be utilized and increased income for the farmers. The objectives of this research were to analyze plant nutrients of mealworm frass and feasibility study on the utilization of mealworm frass in

the organic marigold production process. Results revealed plant nutrients were macronutrient and micronutrient. The primary macronutrients were nitrogen (N), phosphorus (P) and potassium (K) were 4.24, 4.86 and 2.27%, organic matter (OM) was 57.93 %, carbon to nitrogen (C/N) ratio was 9:1, electrical conductivity (EC) was 7.06 and pH was 5.71, respectively. The possibility of organic marigold production was compared with 4 marigold cultivation treatments; chemical fertilizers (T1), wheat bran weevil manure (T2), chicken manure (T3) and without chemical fertilizers (T4). This study was found that the first harvested marigolds flowers was on the 62nd day in mealworm frass treatment while the other treatments were on 66nd day after planting. The average number of flowers of chemical fertilizers (T1), wheat bran weevil manure (T2), chicken manure (T3) and control/no fertilizer application (T4) was 10.333.57, 10.171.74, 6.731.72, and 2.132.37 flowers per plant. Fresh flower weight was 9.373.64, 8.112.43, 7.481.81, and 4.751.05 g. per flower and flower diameter was 6.560.91, 6.110.54, 5.830.50, and 4.770.42 cm, respectively. Data analysis of average number of flowers, fresh flower weight and flower diameter of marigold on mealworm frass and chemical fertilizer were not significant different (P>0.05).