Design and evaluation of the toxic activity of spyrable bioinsecticides against Spodoptera exigua

The beet armyworm is the most devastating insect pest of vegtables crops in Mexico, producing high losses in non-insecticide treated fields. Because pests are evolving to resistance levels to convencional insecticides, there is interest for alternative strategies including the use of biopesticides. In this work were design some specific spyrable Bacillus thuringiensis formulations against this pest. The toxic effect of some bioactives were checked and the B.t. strain HD551 and the neem oil were the most toxic, and the mixture of gelatin-corn spike and gelatin- cabbage powder were the best microencapsulate matrix with phagostimulant effect. The formulation formed by gelatin-spike- B.t., gelatin-cabbage- B.t. and gelatin-spike-Neem B.t. generated the best control in laboratory, causing a 48, 47 and 45% mortality at 24 hours, increasing to 100, 100 and 96% mortality at 7 days. At Greenhouse level, the formulations more efective were gelatin-spike-B.t., gelatin-cabbage-B.t. and gelatin-spike- B.t.Neem, producing the minor number of affected plants and foliage, which is reflected in achieving greater development of plants, causing about 94 and 96% protection.