Studies on the influence of host plants and effect of chemical stimulants on the feeding behavior in the muga silkworm, Antheraea assamensis

Abstract

The feeding habits of Antheraea assamensis, Helfer (Lepidoptera: Saturniidae) larvae towards the leaves of its four different host plants, Persea bombycina King ex. Hook (Laurales: Lauraceae), Litsea polhantha Jussieu, L. salicifolia Roxburgh ex. Nees and L. citrata Blume, and the chemical basis of feeding preference were investigated. Nutritional superiority of young and medium leaves with respect to soluble protein, total phenol and phenylalanine ammonia lyase activity was observed in the leaves of P. bombycina compared to other host plants. Attraction and feeding tests with detached leaves and artificial diet with different chemical stimulants revealed that a mixture of the flavonoids, myrcetin, and 7, 2', 4' trimethoxy dihydroxy flavone with sterol compound β-sitosterol elicited the most biting behavior by A. assamensis larvae. While linalyl acetate alone attracted larvae towards the leaves of the host plants, a mixture of caryophyllene, decyl aldehyde and dodecyl aldehyde was found to both attract them to the host leaves and cause biting behavior. Azaindole was found to deter them from the host plants.

Figure 1.

Settling percent of silkworm larvae with respect to tender (T), medium (Me) and mature (Ma) leaves of different host plants, (1) P. bombycina, (2) L. polyantha, (3) L. salicifolia and (4) L. citrata. High quality figures are available online.

Figure 2.

Diagram showing the survival percent of muga silkworms at 1^st, 1^st-2^nd, 2^nd, 3^rd-4^th, 4^th, and 5^th larval instars fed with different leaf types of (a) P. bombycina, (b) L. polyantha, (c) L. salicifolia and (d) L. citrata. High quality figures are available online.

Figure 3.

Diagram showing (a) Days required (b) weight in grams and (c) survival percent of first and second instar larvae of muga silkworm; 21=control outdoor rearing. High quality figures are available online.