The exogenous application of phytoecdysone was found to increase the cocoon yield and enhance the productivity of silkworm rearing with out variations in the quality of cocoons. One such phytoecdysone has been developed by KSSRDI, Bangalore and commercialised as “Chetana”. This can be used in various ways to improve productivity in sericulture as mentioned below.
i. To promote uniformity in spinning: Approximately 10% of the total labour required for silkworm rearing is needed at the time of picking mature larvae for mounting. During inclement weather conditions or by poor rearing management, the duration of mounting between beginning to closure prolongs for 48 to 72 hrs. This leads to difficulties in mounting, management of labour, harvesting of cocoons and their marketing. By administering ‘Chetana’(Mounting hormone), when the silkworms are about to spin, spinning will be more or less simultaneous, enabling improved efficiency in mounting and uniformity of pupation. In shoot rearing method the uniformity in spinning can save labour as ‘free mounting’ by plastic mountages, as all the larvae begin to spin simultaneously.
ii. Further, it can also be used to reduce the crop loss due to diseases or shortage of mulberry leaf through shortening the fifth instar larval duration
It is established that the quality of feed determines the success of cocoon crops in the sericulture. The nutrition of silkworm Bombyx mori is of primary importance not only for maintenance of its life but also for silk production. Hence, the growth, survival and cocoon production of the silkworm are greatly influenced by nutritional conditions. Feeding mulberry leaves with poor nutritional quality retards silkworm growth. In such cases nutrients are supplemented with mulberry leaves. Hence, the supplementation of essential nutrients is imperative to achieve the targeted foal. In back drop of the above, the study was conducted at KSSRDI to identify the effective sources of carbohydrates, proteins, phagostimulants minerals/salts, growth promoters (from botanicals) as source of fortificants through bioassay and thereby the increment in cocoon yield is ensured. Field evaluation of this fortificant formulation was conducted at rainfed areas of Chamarajanagar district of Karnataka and product is named as “Poshaka”.
Usage: “Poshaka” is a source of nutrients for feed supplementation to silkworm during fifth instar stage. It is sprayed on mulberry leaves (at 1 ml/10 gm of mulberry leaf) and such leaf is offered ad-libitum to silkworms during fifth instar 2nd , 4th, and 5th days (if there is no labour constraint, then the spray may be given 1st day to 6th day). The other feeds during fifth instar should be given with normal mulberry leaf. By usage of “Poshaka” an increment of 15.58% in cocoon yield has been obtained during field trials.
The embryo of the silkworm egg is very sensitive to the changes in the environmental conditions and any such changes will direct effect on the embryonic development thereby affecting the cocoon yield and successive crop. Keeping above points in view Karnataka State Sericulture Research and Development Institute has developed a simple and useful silkworm egg transportation box.
The egg transportation box measures 40cm in width, 30cm in length and 12cm in depth. It is made up of either cardboard or plastic board and internally it is lined with a thermocol leaving an air gap. At the bottom provision has been made to keep wet foam pad or wet cloth to maintain required RH. 500 to 600 layings on 25 – 30 egg sheets can be placed by hanging them to a bar within the box and transported. In case of loose eggs, 2000 layings in 40 loose egg boxes (50 layings in each box)can be loosely arranged in two rows on the loose egg carrying stand and placed into the transportation box and transported.
The egg transportation box ensures safe transportation of silkworm eggs and helps in preventing the damage that may be caused due to sudden changes in the environmental conditions and maintain the health and vigor of the embryo.
Production of quality silkworm seed is an important prerequisite for the success of cocoon crop. Quality of the seed refers to number of eggs per laying (fecundity), uniformity in the laying and disease freeness. Disease freeness in the egg mainly refers to pebrine disease than any other diseases and mother moth examination is the only method which is commercially recommended for the egg produces at present. One of the oldest recommended methods for early detection of pebrine spores is forced moth eclosion followed by microscopic examination. Forced eclsion is achieved by subjecting a sample seed cocoon at higher temperature. However, from the survey conducted by the staff of SW Seed Technology laboratory in the seed areas and with private RSPs it was observed that forced eclosion method is seldom practiced mainly because of lack of appropriate technology. Therefore, that was a need to develop equipment which helps the egg producer to prepare quality seed.
The temperature inside the box should be maintained at 30 32°C by adjusting the thermostat. The top ventilator is opened appropriately so as to facilitate adequate aeration without much fluctuation in temperature. The cocoons are to be kept inside the box till they emerge. Moth emergence takes place 2 -3- days prior to those kept in ambient room temperatures. In general moth examination procedure are to be followed on those early emerged moths and checked for occurrence of disease. As these moths are kept in high temperatures, the rate of multiplication of pebrine spores will also be higher; thereby detection of spores will be easier. This also helps to divert the pebrinised lot for reeling, thereby saving money and labour, besides preventing spread the disease.
Moth eclosion through new found “early eclosion box” will not only help in early detection of pebrine spores in moths, but also in diversion of infected seed cocoons to reeling and thereby, contaminant of spread of the disease.
Two days before hatching, the colour of the eggs changes into a lighter shade with a blue point i.e. pin head stage.
Next day the egg colour change into blue and is called body pigmentation stage.
At pin head stage the eggs are transferred to dark room, this process is called black boxing of eggs.
Providing ideal environmental conditions to the eggs for healthy growth and development of the embryo is referred as “Incubation”. Embryo grows robust using most of its reserve food under 250 C temperature and 80% RH conditions. For this purpose the ordinary mud pot of around 16-18 litres capacity has to be put in the wet sand bed (covered with bricks) up to it’s rim. The conditioning of the environment is to be done previous day. In this pot we can incubate the egg sheets of about 300 DFLs. While incubation period the mouth of the pot should not be closed or it may be covered with wet kora cloth. In temperate regions this can also be used to preserve the chawki leaf. This technology is easy to adopt, cheap and more effective.
This is one of the vital technologies developed by KSSRDI which provides regulative temperature and relative humidity for chawki silkworms. This has both heater and thermostat. Based on this concept the present CRC buildings have been designed and utilised for commercial purpose.
Seri-calender is one of the recent innovations from KSSRDI. This is helpful in planning the whole schedules of sericulture activities. The details are available in the App. in android phones/internet.