The following points highlight the four major enemies of silkworms. The enemies are: 1. Beetles 2. Ants 3. Straw Mite 4. 4. Vertebrates Predators.
Silkworm: Enemy # 1. Beetles:
Many species of dermestid beetles can cause a great damage to sericulture. Some of them include Dermestes vorax, D. valpinus, D. coar, Antherenus verhasi, A. piceus, etc. Their larvae as well as adults feed on the silk-pupae, thus they pierce the freshly spun, stored or stifled cocoon and make them unreelable.
Control Measures:
(i) Frequent cleaning of rearing house and storerooms,
ADVERTISEMENTS:
(ii) Repeated turning of stored cocoons to check pest infestation,
(iii) Fumigation of cocoon storage room with methyl bromide can destroy the beetles’ larvae and
(iv) Spraying of BHC in the storeroom.
Silkworm: Enemy # 2. Ants:
Many varieties of ants can attack the silkworms in the rearing tray, the spinning larvae as well as cocoons on the mountages.
ADVERTISEMENTS:
Use of ant well below the rearing stand and Raksha Rekha can prevent such ant attack.
Silkworm: Enemy # 3. Straw Mite:
Bamboos used for making rearing house, sometimes are contaminated with straw mites (Pedicolus ventricosus), which may be transported accidentally to rearing trays of silkworms. The female mites attach themselves to the larvae or pupae and draw nourishment from their body, leading to their death. The mites also secrete toxin which can kill the hosts.
The mite infested larvae lose appetite and become inactive. They vomit green fluid and excrete black fluid. Ultimately their dorsal vessel shows slow and irregular pulsation and then they die.
Control Measures:
ADVERTISEMENTS:
(i) Materials taken for making rearing room should be checked carefully,
(ii) Rice or wheat straw should not be stored near the rearing room and
(iii) Acaricide may be applied in rearing room if mites are noticed there.
Silkworm: Enemy # 4. Vertebrates Predators::
Some larger predatory vertebrate animals like, rats, squirrels, birds may enter the rearing room to feed the larvae or pupae. Their entry may be prevented by putting wire mesh on the windows and holes of rearing rooms.