Southwestern corn borer (Diatraea grandiosella Dyar) is a serious pest
of corn (Zea mays L.) in the southern USA, Lack of reliable technique
s for evaluating resistance after anthesis is a major problem. The obj
ective was to develop a laboratory bioassay for evaluating southwester
n corn borer larval growth on diets comprised primarily of lyophilized
husks of corn inbred lines, Diets were prepared by adding 15 g of lyo
philized husk tissue collected within 3 d after silk emergence to a mi
xture of 250 mL distilled water, 2400 mg agar, 12.5 mg gentamicin sulf
ate, 132 mg sorbic acid, and 528 mg ascorbic acid. Larvae were weighed
after feeding on the test diet for 21 d. Larvae fed diets containing
husks of different inbred lines varied significantly. Because southwes
tern corn borer larvae that infest corn plants at or after anthesis fe
ed initially on husks, this bioassay is a potentially useful technique
for identifying resistant germplasm.