Preliminary Study of Semi-synthetic Artificial Diet for the Idea leuconoe clara (Butler) (Lepidoptera: Nymphalidae)

Abstract

In this paper, We emphasized on the research and development of the semi-synthetic artificial diet for the giant danaine butterfly, Idea leuconoe clara (Butler). Our experiment involved feeding the larvae leaves of host plant, Helicoid-stamenal Parsonia, Parsonia laevigata (Moon) Alston, as control group, and fed the artificial diet as experimental group, In order to study the feasibility of rearing this species with the artificial diet, we reared giant danaine butterfly individually and kept them in the growth chamber with a temperature of 25±1℃, a humidity of 80±5 % RH, and a photoperiod of 14L: 10D as the controlled conditions. Hatching larvae were individually reared with either the semi-synthetic artificial diet or the leaves of Helicoid-stamenal Parsonia until adult emergence. The survival rate of the experimental group, from the first instar larvae of new hatching to became adults, was 58.3%, which was less than the control group 78.3%. The average developmental period of the experimental group, from the first instar larvae of new hatching to became adults, was 10.7 days longer than those of the control group-that is, 47.15 ± 0.29 and 36.40 ± 0.28 days, respectively. This butterfly species, reared with the artificial diet, had a lower survival rate during every life stage and had a longer developmental period. The width of the head capsule in the experimental group from those of the first instar to the fourth instar larvae was smaller than those of the control group, and the differences between the various instars from the two groups were all significant. However, the head capsule's width of the two groups, in the fifth instar larvae, was the same. Therefore, the threshold value of head capsule's width for the larva's development to pupa was above 4.11 mm. The increment of the head capsule's width of the larva was in accordance with the increase in the larval instar stage; it maintained a ratio of 1.5 times. The experiment with this species accorded with Dyar's law. Though up to 60% of the adult wings from the experimental group were creased and unable to fly normally, the appearance and wing color of both groups had no difference. Those adults, from the experimental group, that had normal wings could fly normally. They had mating and reproductive capability. Though some of the biological characteristics of the giant danaine butterfly were lower than those of the control group, the experiment reared adults, from the experimental group, that had a survival rate of over 58.3%. As a result, rearing the giant danaine butterfly with the artificial diet is feasible, but the diet still has some shortcomings that need to be studied and improved in the future.