Outdoor rearing exposes the muga crop to a standing community of parasitoids and predators drawn from seven families. Losses are consistently heavier in pre-seed and seed crops than in commercial crops — compounding the seed shortage that already constrains the system.
The pest community
| 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 |
| Birds and other vertebrates | — | Background loss through the crop |
Muga: uzi fly management
The uzi fly peaks from November to April and is worst in Chotua (March–April), striking fourth and fifth instar larvae and then damaging cocoons at harvest — destroying the seed cocoons on which Jethua depends. Reported crop losses run 20–40 %.
- How it works: the gravid female lays on the dorsal and dorso-lateral integument; maggots bore in and feed on internal tissue; a heavy fourth-instar infestation means the worm never spins. Mature maggots exit and pupate in the field or, if infested cocoons are carried in, inside the grainage hall.
- Physical exclusion first: a properly erected and maintained nylon net remains the primary defence.
- Sanitation: collect and destroy infested larvae and cocoons; never carry suspect cocoons into the grainage.
- Biological control: Nesolynx thymus (Eulophidae), a gregarious pupal endoparasitoid, is host-specific, harmless to the silkworm and can be mass-multiplied and released around rearing fields. Exoristobia philippinensis occurs locally in the same role.
- Chemical control is largely closed off: the muga silkworm is unusually sensitive to pesticides.
Because chemical control is effectively unavailable, uzi management in muga is a net,
sanitation and biocontrol problem — there is no rescue treatment once a crop is
infested. The institute’s 2009 biological control package raises cocoon yield by 30 %
in the Jarua and Chotua crops at a benefit–cost ratio of 2.03 : 1.
Pests of the eri silkworm
| Pest | Nature | Management |
|---|---|---|
| Uzi fly (Exorista sorbillans) | Endo-larval parasitoid, year-round, peaking in the rains; leaves a black scar on the larval integument | Wire mesh or nylon net on all doors and windows; self-closing doors; an ante-chamber at the rearing house entrance; release of Nesolynx thymus; never dispose of silkworm litter in the open |
| Ant (Oecophylla smaragdina) | Attacks early instars | Ant wells at the base of every rearing stand; repellent barriers |
| Cockroach (Periplaneta americana) | Attacks early instars | Ant wells and repellent barriers; strict rearing-house hygiene |
| Rat (Rattus rattus) | Damages eggs, larvae, pupae, cocoons and moths | Traps or baits |
| Lizard (Hemidactylus flaviviridis) | Attacks larvae during early rearing | Traps; fly-proofing of the rearing house |
Indoor rearing makes eri pest management a question of building integrity — mesh,
doors, ante-chambers and ant wells — rather than field intervention. 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.