CHEMICALLY AND PHOTOPERIODICALLY INDUCED DIAPAUSE DEVELOPMENT IN THE EUROPEAN CORN BORER, OSTRINIA NUBILALIS

Abstract

Diapause development of larval European corn borers was shown to be rate-controlled by photoperiod, with 16-hour daylengths causing a developmental rate 5 times that observed under 12-hour daylengths. Continuous darkness had the effect of maintaining the developmental rate established by the photoperiods last experienced by the diapausing larvae. Diapause development was found to be irreversible and cumulative. Neither water nor central nervous system stimulants accelerated diapause development. Large injected doses of certain ammonium compounds greatly accelerated diapause development. Typically, a 100 mg larva injected with 400 ug of ammonium acetate and held under a 16-hour daylength would complete diapause development in approximately one-third the time required by the 16-hour daylength treatment alone.