Protection of Mulberry Silkworm Eggs

Technical measures to regulate and control the storage environment of silkworm eggs, make the silkworm eggs enter and release diapause uniformly, keep the egg quality full and strong, and have good hatching. According to the period and season of silkworm eggs protection, it can be divided into early spawning protection, summer and early autumn protection, mid-autumn to early winter protection, winter protection, and artificial over-summer of autumn over-year-old species.

Early spawning protection

After the silkworm eggs are laid, the eggs begin to undergo maturation and division, complete the fertilization process, nuclear division and proliferation to form embryos and a series of developmental processes. At this time, the resistance to high and low temperature is the weakest, and the operation and treatment should avoid violent vibration, friction, accumulation and sudden temperature changes. At the time of laying eggs, the diapause of the eggs has not been completed, and it needs to be protected in a silkworm breeding room with a temperature of 24～25℃ and a humidity of 75～80%. After 7～10 days of embryonic development, the respiration becomes weak, and the diapause is physiologically entered. Expect.

Summer and early autumn protection

Silkworm eggs need to experience a certain period of high temperature after entering the diapause period to consolidate their diapause. 25℃ is the optimum temperature to complete diapause. The protection temperature from mid-June to early September is based on 25℃, and the range is 24～27℃. The longer the silkworm eggs are exposed to 25°C, the slower the subsequent release of diapause. The longer the exposure to low temperature, the stronger the resistance to cold storage. However, exposure to high temperatures such as over 30°C or more than 100 days will be harmful to silkworm eggs, and the resistance to cold storage will be weakened. The number of days exposed to 25°C is within the safe range of 40-60 days. The two-chemical original species of Chinese silkworm varieties are about 40 days; the first generation hybrids can reach 60 days. The humidity should be 75%. The high temperature above 30°C will increase dead eggs, reduce the hatching rate, and damage the body and cocoon quality of silk cocoon breeding. Excessive humidity is prone to mold, which harms the physiology of silkworm eggs; dryness will consume more nutrients in the eggs and damage the egg quality. July to August often encounter high temperature or high temperature and dry weather, the temperature and humidity of the silkworm eggs must be adjusted to protect the environment.

Protection from Mid-Autumn to Early Winter

From mid-September to mid-November, the natural temperature gradually decreases. After silkworm eggs are exposed to high temperatures for a certain number of days, the temperature in the silkworm breeding room needs to be lowered. It is best to have a period of protection at 20-22°C. Because 20 to 22 ℃ neither promotes the elimination of diapause, but also harmless to the physiology of silkworm eggs. When the temperature of the silkworm breeding room drops below 20℃, it can be protected by natural temperature. Since November, the natural temperature in the silkworm area of ​​the Yangtze River Basin has gradually dropped from 20°C to 17-18°C, and then to about 15°C. When the silkworm eggs are exposed to a low temperature below 15°C, some silkworm eggs begin to release diapause, and at the same time, the sensitivity to higher temperatures increases. That is, silkworm eggs that have been exposed to low temperature for quite a few days should avoid exposure to high temperature, so as not to cause the embryos to begin to develop and cause unevenness, leading to poor hatching in the future. Also, when cold air strikes, it is necessary to prevent exposure to low temperatures below 15°C, and do not release diapause prematurely. This is the key to adjusting the protection temperature of silkworm eggs at the turn of autumn and winter. For silkworm species in warm areas, the high temperature lasts too long, and the low temperature necessary to release diapause is too few, which easily makes the release of diapause insufficient; or the eggs that are released early in the release of diapause will begin to develop, resulting in uneven embryonic development. If the natural temperature does not drop below 20°C by mid-October, artificial cooling measures are required to gradually reduce the temperature of the seeding room until it reaches about 5°C in mid-December.

Winter protection

From mid-November, the protection temperature will gradually decrease from 15°C, and the humidity will maintain 75% after 12°C, 10°C, 7.5°C and 5°C. The winter protection is the low temperature protection that makes the silkworm eggs neatly release the diapause. The most effective temperature for relieving diapause is 7.5℃～5℃. In order to make all silkworm species develop neatly and uniformly, a slightly lower temperature of 5℃ protection is beneficial and safe. 5℃ also has the effect of inhibiting the development of premature release of diapause eggs and making all silkworm egg embryos develop uniformly.

In early December, when the temperature drops below the appropriate temperature of the bathing water, the frame-type and flat-attached silkworm seeds are disinfected, the bathing seeds and the loose eggs are washed off. The bath water temperature is in the range of 10℃～15℃. In the process of washing off, silkworm eggs are stimulated by friction, vibration and water temperature, which will promote the elimination of diapause (activation) of silkworm eggs. The degree is equivalent to 5℃ protection for 20 days. Therefore, loose eggs are fully protected at 5℃ after bathing. It must be refrigerated at 2.5°C on the 40th. After the frame-type and flat-attached silkworm seeds are bathed for 60 days in an environment of 5°C, they must be refrigerated at 2.5°C. 5°C cannot inhibit the development of activated eggs for a long time. For the protection of silkworm eggs in winter, 5°C is the temperature for relieving diapause, not the temperature for refrigeration. In order to prevent excessive consumption of egg mass, it is necessary to refrigerate it at 2.5°C or 0°C in an appropriate period to inhibit its development. Therefore, the winter protection has a dual effect, that is, the low-temperature protection of the diapause eggs (active eggs) and the cold protection to prevent the viability of the active eggs from decreasing. The most important thing is to make the silkworm eggs of different seed production periods, locations and protection conditions in summer and autumn into uniform silkworm eggs.