Date of Award

1981

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Entomology

Abstract

Male sugarcane borer, Diatraea saccharalis (F.), larvae at egg hatch were equal in weight to females, but on artificial diet, pupated in less time and achieved a smaller larval maximum and 1 day old pupal weight. The peak period for egg hatch and ecdysis was within a few hours after lights-on, and pupation occurred at random. Males completed larval development in 5 and 6 stadia and females in 6 stadia. Net larval growth was greater for males and females completing development in 6 stadia than in 5 stadia. Ecdysis to the last stadium occurred during the 12th to 14th day after egg hatch. By choosing last stadium 0 day old borers (GREATERTHEQ) 70 mg and 1 day old borers (GREATERTHEQ) 140 mg, a synchronous population of female sugarcane borers was obtained which completed the last stadium in 5 days. The prepupal stage occurred during the 5th day. Synchronous female borers were used in a physiological study of growth during the last stadium. The results were consistent with the literature and were reproducible even when tested as much as 1 year apart. A peak in the plasma juvenile hormone esterase (JHE) activity occurred near the time when female last stadium borers reached their maximum weight, and a second peak of plasma JHE activity and a peak in the plasma (alpha)-naphthyl acetate esterase ((alpha)-NAE) activity occurred at the prepupal stage. The peak JHE activity was 1.73 nmoles/min/ml and the peak (alpha)-NAE activity was 123.6 nmoles/min/ml. The last stadium JHE and (alpha)-NAE activity pattern, the inhibition profile, enzyme stability, isoelectric focusing, gel filtration, and HPLC analysis indicated that JH I and JH III was metabolized by the same JH specific esterase(s) distinct from the (alpha)-NAE's. Juvenile hormone I was metabolized at twice the rate of JH III. Two JHE forms were resolved by isoelectric focusing and by HPLC analysis. The surgarcane borer JHE activity was not inhibited by paraoxon as it was in other Lepidoptera studied. The apparent K(,m) for the JHE metabolism of JH I was 2.80 uM.

Pages

99

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