The compatibility of Bacillus thuringiensis Cry protein-solubilizing buffers with the droplet feeding method in fall armyworm larvae.

• Determined volume of Cry protein-solubilizing buffers imbibed by FAW larvae. • Buffer composition affected the volume of buffer imbibed by larvae. • Some buffers were phagostimulatory whereas others had antifeeding effects. • Cry protein-solubilizing buffers are compatible with droplet feeding assays in FAW. • Volume imbibed data will facilitate LD 50 assays of alkali-solubilized Cry proteins. The volumes of alkaline (pH > 10), Bacillus thuringiensis Cry protein-solubilizing buffers imbibed by fall armyworm larvae in droplet feeding assays were determined. The buffers differed in the presence or concentration of key ingredients, including buffering agents, chelating agents, reducing agents, and protease inhibitors. For both first and second instar larvae, the buffer used had a significant effect on the volume imbibed. The study showed that the droplet feeding method is compatible with Cry protein-solubilizing buffers, but that it is important to determine the volume imbibed for every buffer used in dose-dependent bioassays in order to reduce dose errors. [ABSTRACT FROM AUTHOR]