Rl. Gillespie et al., PALATABILITY OF FLOUR GRANULAR FORMULATIONS TO EUROPEAN CORN-BORER LARVAE (LEPIDOPTERA, PYRALIDAE), Journal of economic entomology, 87(2), 1994, pp. 452-457
Newly developed techniques for producing starch and flour granule form
ulations encapsulating Bacillus thuringiensis Berliner have led to a l
arge number of potentially effective baits for Ostrinia nubilalis (Hub
ner). One aspect of these formulations that must be considered is thei
r palatability to com borer larvae. Experiments were conducted to dete
rmine palatability of several formulations in two-choice preference te
sts. Com borer larvae preferred flour granules containing cotton leave
s or a commercially available feeding stimulant, Coax, or both. Larvae
rejected granules formulated with CaCl2. Granules made with molasses
were intermediate in palatability. When the granules were formulated w
ith 1,600 International Units (IU) B. thuringiensis per mg granules an
d 20 mg of granules were sprinkled on cotton leaves, several formulati
ons killed >70% of the corn borer larvae that fed on treated leaves; o
ther formulations killed <40% of the test insects. Mortality was reduc
ed when larvae were exposed to cotton leaves sprinkled with granules f
ormulated with CaCl2 when compared with those formulated with cotton l
eaves or Coax, or both. The dose of B. thuringiensis could be reduced
by 3/4 (i.e., to 400 IU/mg) without affecting the level of larval mort
ality if the pathogen was entrapped in granules containing cotton leaf
tissue + Coax or only cotton leaf tissue.