A reference collection of the insects that matter to muga, eri and oak tasar culture — the sericigenous species themselves, the parasitoids and predators that attack them, and the beneficial insects used against those. Outdoor rearing means the muga crop shares its field with a standing community drawn from seven families, so identifying what is present is the first step in doing anything about it.
Sericigenous species
| Species | Common name | Status |
|---|---|---|
| Antheraea assamensis Helfer | Muga | Semi-domesticated; endemic to the Brahmaputra valley and adjoining Garo hills. Lowest chromosome number in the genus, n = 15, ZZ/ZO sex chromosome system. |
| Samia ricini (Donovan) | Eri | The only fully domesticated member of the Saturniidae; multivoltine, polyphagous, reared indoors. |
| Antheraea proylei J. | Oak tasar | Reared in Manipur; breed C27 established and popularised from RSRS, Imphal. |
| Antheraea frithi Moore | — | Rearing and grainage technology standardised at RSRS, Imphal. |
| Samia canningi | Wild eri | Wild progenitor of S. ricini. |
| Samia kohlli; Samia fulva | — | Wild; Mizoram and Nagaland, and endemic to the Andaman and Nicobar Islands respectively. |
A good number of allied Antheraea species also occur in North East India in their natural habitat.
Parasitoids and predators of muga
| Organism | Family / order | Role |
|---|---|---|
| Exorista sorbillans | Diptera: Tachinidae | Uzi fly — principal larval-pupal endoparasitoid |
| Blepharipa zebina | Diptera: Tachinidae | Second uzi species on muga |
| Apanteles glomeratus | Hymenoptera: Braconidae | Larval parasitoid |
| Xanthopimpla pedator | Hymenoptera: Ichneumonidae | Pupal endoparasitoid; locates the pupa through the cocoon wall |
| Eocanthecona furcellata | Hemiptera: Pentatomidae | Predatory stink bug |
| Sycanus collaris | Hemiptera: Reduviidae | Assassin bug |
| Oecophylla smaragdina; Componotus sp. | Hymenoptera: Formicidae | Red weaver ant; carpenter ant |
| Vespa orientalis | Hymenoptera: Vespidae | Predatory wasp |
| Hierodula westwoodii | Mantodea: Mantidae | Praying mantis |
Losses are consistently heavier in pre-seed and seed crops than in commercial crops, which
compounds the seed shortage rather than merely reducing a harvest. Uzi fly alone accounts
for reported crop losses of 20–40 %, peaking November to April and worst in Chotua.
Beneficial insects held for biological control
| Organism | Family | Use |
|---|---|---|
| Nesolynx thymus | Hymenoptera: Eulophidae | Gregarious pupal endoparasitoid of the uzi fly. Host-specific and harmless to the silkworm; mass-multiplied and released around rearing fields at least three months ahead of the crop. |
| Exoristobia philippinensis | Hymenoptera: Encyrtidae | Occurs locally in the same role. Released with N. thymus; raises cocoon yield by 30 % in the Jarua and Chotua crops, B:C ratio 2.03 : 1. |
| Trichogramma sp. | Hymenoptera: Trichogrammatidae | Egg parasitoid released during stem borer oviposition; part of the integrated stem borer package controlling infestation up to 80 %. |
Biological control is not a preference here, it is a necessity. The muga
silkworm is unusually sensitive to pesticides, so chemical control of its parasitoids is
largely closed off. Physical exclusion by nylon net, field sanitation and released
parasitoids are the whole toolkit — which is why maintaining a living reference
collection of both the pests and their natural enemies is a working requirement rather
than a curatorial one.
Pests of the eri rearing house
| Pest | Nature |
|---|---|
| Uzi fly (Exorista sorbillans) | Endo-larval parasitoid, year-round, peaking in the rains; leaves a black scar on the larval integument |
| Ant (Oecophylla smaragdina) | Attacks early instars |
| Cockroach (Periplaneta americana) | Attacks early instars |
| Rat (Rattus rattus) | Damages eggs, larvae, pupae, cocoons and moths |
| Lizard (Hemidactylus flaviviridis) | Attacks larvae during early rearing |
The same uzi fly attacks both silkworms, so a muga rearing field and an eri rearing house in the same locality share a pest population and should be managed as one problem. Management detail on Insect Pests & Predators.