INFLUENCE OF PHOTOPERIOD ON THE LIFE-CYCLE OF ECTOMYELOIS-CERATONIAE (ZELLER) (LEPIDOPTERA, PYRALIDAE)

Diapause in fully grown larvae of Ectomyelois ceratoniae was induced by low temperature and short photoperiods. When larvae were reared at 30°C, 70% r.h. there was no diapause in a light regime of 12 hr light followed by 12 hr darkness ( 12L 12D), and only 20% entered a weak diapause in continuous darkness. However, at 20°C, 70% r.h. there was no diapause in 16L 8D but almost all larvae entered diapause in 12L 12D. At 20°C diapause delayed adult emergence by an average of 111 days, compared with about 50 days at 30°C. Survival to adult at 30°C was 75% or more at most photoperiods, but at 12L 12D and 13L 11D it was less than 50%. At 20°C survival was about 70% at the two photoperiods tested. A slight effect of photoperiod on non-diapause growth rates was observed. Above 16 hr light longer photoperiods reduced the mean developmental period from egg hatch to adult emergence, by 4 days at 20L 4D and 6 days at 24L 0D. The significance of diapause in this species in relation to its potential as a pest is discussed. © 1979.