Evaluation of potential microencapsulated agents for oral entomopathogens with phagostimulant activity against Spodoptera exigua (Hber)

The efficacy of bioinsecticides that act by ingestion can be improved using phagostimulants that increase the consumption of the pathogen. Three biopolymers, gelatin, pectin, and corn starch, with five additive phagostimulants, maize spike, fresh maize cobs, alfalfa, sorghum leaves, and cabbage, were used to form 18 microencapsulant matrices. The matrices were evaluated for feeding preferences by beet armyworm, Spodoptera exigua (Hbner) (Lepidoptera: Noctuidae). Ten neonate larvae were given a choice between two different matrices or between one matrix and a small piece of fresh cabbage used as a check. Results showed that beet armyworm larvae preferred matrices of gelatin and pectin biopolymers and additives of cabbage powder or maize spike over fresh cabbage. The best microencapsulant agents were gelatin-cabbage and gelatin-maize spike, attracting 5.47 and 5.42 larvae, respectively. The larvae preferred fresh cabbage when given a choice between fresh cabbage and a biopolymer without any phagostimulant. Phagostimulants can be added to biopesticides to increase the consumption rate and kill more pests. Gelatin was the best biopolymer and the phagostimulants maize spike and cabbage were very palatable to beet armyworm larvae.