Utilization of several biopolymers for granular formulations of Bacillus thuringiensis

Bacillus thuringiensis variety aizawai was encapsulated within several biopolymers (gelatin, pectin, chitin, alginate, and cornstarch) and assayed for biological activity against neonate Trichoplusia ni (Hubner). Granules were made with various solvents, and a total of 8 formulations were tested. Nearly 100% mortality occurred with all formulations except those made with chitin. B. thuringiensis formulations made with gelatin, pectin, or cornstarch and stored in the laboratory for 12 mo exhibited no detectable decrease in toxic activity against T. ni larvae. Assays that measured resistance to wash-off demonstrated that granules made with gelatin and pectin were retained on cotton leaves. Experiments were conducted to determine palatability of several formulations in 2-choice preference tests. T. ni larvae preferred granules containing gelatin or pectin.