Agroecosystem Stability and Breakdown Leaves on Mustard Cropping after Application by the Bacillus thuringiensis

. The purpose of this research are 1) To test the effect of the application of Bacillus thuringiensis reproduced using the artificial medium against mustard leaf damage caused by leaf-eating pests, 2) Comparing the stability of the mustard plant agroecosystem after applicated by various concentrations of B. thuringiensis. Tests using a randomized block design with 5 treatments and 4 replications. The treatments were a) Control (application by water), b) Application B. thuringiensis using a concentration of 2 cc/l of water, c) Application B. thuringiensis using a concentration of 4 cc/l of water, d) Application B. thuringiensis using a concentration of 6 cc/l of water, e) Application B. thuringiensis using a concentration of 8 cc/l of water. Observed variables consist of any number of arthropod species found and the intensity of leaf damage. Data were analyzed by analysis of variance using a randomized block design, while the difference between the effect of treatment is determined by LSD. agro-ecosystem stability is determined by determining the diversity index by Shannon and Weaver, Domination Index, Richness Index of species, and the similarity index. Research results can be summarized as follows 1) Application B. thuringiensis can reduce the intensity of the damage caused by leaf-eating pests in crop mustard mustard, 2) The concentration of B. thuringiensis the most severe damage is low intensity is a concentration of 6 cc/l and 8 cc/l, 3) Planting mustard has the highest stability of mustard plant ecosystem treated B. thuringiensis applications with a concentration of 4 cc/l with a diversity index of 1.867.