Photoperiodically induced delayed metamorphosis in the sugarcane borer, Diatraea saccharalis (Lepidoptera: Pyralidae)

Delayed metamorphosis in the sugarcane borer, Diatraea saccharalis (F.), was induced within the first two larval stadia by photophases from 10 to 13 h (at 21 degree C) but was not initiated until three to four stadia later. From the time of the first to the penultimate LD 14:10 stadium, the duration of each stadium and the head capsule width were identical for borers kept on photoperiods of LD 12:12 and LD 14:10. The LD 14:10 last stadium was shorter than the corresponding LD 12:12 stadium. Last-stadium LD 14:10 borers pupated, while borers maintained at LD 12:12 continued to feed, grow, and molt, eventually doubling the maximal larval weight of LD 14:10 borers. Transition from spotted to immaculate borers occurred at LD 12:12 within two molts after LD 14:10 pupation.