MEASUREMENT OF THE LIPOPHORIN TITER IN THE LARVAL HEMOLYMPH OF THE SOUTHWESTERN CORN-BORER, DIATRAEA-GRANDIOSELLA, BY ELISA

An enzyme-linked immunosorbent assay (ELISA) was developed to measure the lipophorin titer in the hemolymph of the southwestern corn borer, Diatraea grandiosella. Results obtained using indirect and direct ELISA methods were compared. The indirect ELISA was then used to compare the lipophorin titers in the hemolymph of non-diapause, pre-diapause, and diapause larvae. The mean lipophorin titer in the hemolymph of non-diapause larvae was 2.5 mg/ml in fourth instar larvae and increased to 3.9 mg/ml during the fifth and sixth instars. The mean lipophorin titer in the hemolymph of pre-diapause larvae was 2.3 mg/ml in 13 day old larvae and increased to 4.0 mg/ml in 22 day old larvae. The mean titer then decreased significantly until day 40, but increased to 5.1 mg/ml in 49 day old larvae after they had entered diapause and held at c. 3 mg/ml until larvae were about 70 days old, when it increased to c. 5 mg/ml and remained constant for at least the next 20 days. The amount of lipid in the hemolymph was also measured and correlated to the amount of lipophorin present.