ARS | Publication request: UTILIZATION OF SEVERAL BIOPOLYMERS FOR GRANULAR FORMULATIONS OF BACILLUS THURINGIENSIS

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 1998
Publication Date: N/A

Interpretive Summary: Control of pest insects is usually accomplished with synthetic chemical pesticides. While these can be very effective, there is a perception that environmental damage may occur and that beneficial insects are also killed. In response to these perceptions biopesticides are under commercial development as replacements for chemicals. Biopesticides, however, lose activity quickly in the field after application and acceptance of these products has been limited. Here, we report on the use of naturally-occurring polymers derived from gelatin, pectin, chitin, and starch to help extend the activity of a biopesticide, Bacillus thuringiensis. We found that each of these polymers have different attributes and that pectin and gelatin were superior materials. Pectin and gelatin protected B. thuringiensis from sunlight and from rainfall, thus extending the activity under field conditions. Primary users of this information are other scientists in academia and industry developing biopesticides and ultimate users, should the technology be commercialized, would include people involved in crop protection.

Technical Abstract: Bacillus thuringiensis var. aizawai was encapsulated within several biopolymers (gelatin, pectin, chitin, alginate and cornstarch) and assayed for biological activity against neonate Trichoplusia ni. Nearly 100% mortality occurred with all formulations except chitin. B. thuringiensis encapsulated with gelatin, pectin and cornstarch stored in the laboratory for 12 months exhibited no detectable decrease in spore viability or 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 two-choice preference tests. T. ni larvae preferred granules containing gelatin or pectin.