Construction and Analysis of Two-sex Life Table on Experimental Population of Diaphania angustalis

  Objective  Larval development, fecundity and feeding of Diaphania angustalis (Snellen), a major pest that infests blackboard trees by larva feeding on leaves and leaf-rolls causing serious damage on the ornamental and medicinal plants, were studied to determine the effective controlling period.

  Method  The development, fecundity, feeding habit and survival rate of D. angustalis larvae were deciphered with the constructed two-sex life table of the pest from an experimental population.

  Results  At the temperature of (28±1)℃, relative humidity of (70±5)% and photoperiod of L:D=12:12, the mean generation time of the moth was found to be (45.42±0.55)d; the intrinsic rate of increase, (0.099±0.006)d; the finite rate of increase, (1.104±0.007)d; and, the net reproduction rate, (92.28±22.50) offspring. The fecundity of a female adult was(369.20±65.44)eggs, 1 267 at the highest. The number and reproduction of the population increased with time. At larva stage, the development time and feed consumption increased with age. It took significantly longer for the older larvae than the younger larvae to develop, and a larva consumed significantly more in the 4^th to 6^th than 1^st to 3^rd instar stage.

  Conclusion  The most effective period for controlling D. angustalis appeared to fall on the 1^st to 3^rd instar larvae.