How to cultivate Chironomus larvae?

The main results are as follows: (1) artificial egg collection is completed with a special artificial egg collection box. The size of artificial egg collection box, the ratio of biological density to sex of Chironomus, suitable temperature, humidity, lighting and adult bait are all conditions that must be considered in artificial egg collection.

The size of the ① egg collection box is 1m × 1m × 2m. The box is made of 4cm square Cunninghamia lanceolata. There is an insect net for mosquito prevention on the outside, which is covered with transparent plastic sheeting to maintain the humidity inside the box and to observe from the outside.

The individual density and sex ratio of ② Chironomus collected the adults or larvae of Chironomus and placed them in the human egg collection box. Its individual density is one of the main factors affecting the fertilization rate. At a density of 2 000 pieces per meter. Above, more than 80% of the fertilization rate can be obtained. With the increase of density, the fertilization rate also increased. When the density is 4000 pieces per meter. The fertilization rate reached 90%. Sex ratio is one of the important conditions in biology, and the most suitable condition is the number of male and female Chironomus, or slightly more males than females. Therefore, in the process of egg collection, attention should be paid to the supplement of male individuals.

The optimum temperature range of ③ is 23 ℃ ~ 25 ℃. When the temperature is lower than 20 ℃ or higher than 28 ℃, the fertilization rate is sudden. When the temperature is low, it can be solved by artificial heating. Generally, two 40-watt light bulbs are placed in the egg collection box to dissipate heat and controlled by a constant temperature relay.

The air relative humidity with suitable ④ humidity is a necessary condition for mating between male and female Chironomus. A fertilization rate of 80% to 85% can be obtained when the relative humidity is above 90%; when the relative humidity is less than 80%, the fertilization rate decreases to less than zo%. The humidity adjustment can be controlled by the sprinkler in the egg collection box and the evaporation can be prevented by the plastic sheet outside the box.

The results of ⑤ lighting research show that the best condition of intermittent lighting is intermittent lighting for 4 times in 24 hours. When the lights are turned off for 30 minutes and the light is illuminated intermittently for 5.5 hours each time, the fertilization rate is more than 80%. Start laying eggs during lighting, and the number of eggs laid within 2 hours of lighting is 60% of the total number of eggs laid.

The ⑥ bait is placed in the basin in the egg collection box, or sprayed on the cloth screen suspended in the egg collection box. A higher fertilization rate can be obtained when the adult diet is 2% sucrose, 2% honey or a mixture of both.

Using the conditions of the above egg collection box, the duration of fertilized egg blocks is 12 to 15 days, and the highest number of eggs can be obtained in one day is 400 eggs and 750 eggs (an average of 100 eggs and 120 eggs). Assuming that the average number of eggs in an egg block is 500, 100000 individuals can be collected every day, and 1.4 million individuals, or about 7 kg larvae, can be obtained after 2 weeks.

(2) medium

① Agar medium dissolved Agar in hot water, prepared 0.8% Agar solution, cooled to 50 ℃ before adding milk. According to the addition amount of milk, increase or decrease the addition amount of distilled water, so that the Agar concentration is finally adjusted to 0.75%. Then pour 25 ml of the medium solution into a glass dish with a diameter of 90 mm to cool the Agar and add 10 ml of distilled water to it.

⑦ clay-milk medium take a certain amount of clay for tile burning, add 10 times heavy distilled water, grind it into a dispersed colloid in a large mortar, remove the sand, sterilize it with a 117.68 KPA autoclave for 30 minutes, cool, add a certain amount of milk, and quickly begin to agglutinate, clay particles and milk together to form a massive precipitation, which can be used as a culture medium for larvae.

⑧ Clay A plant leaf culture medium takes weeds or mulberry leaves or marine large-leaf algae, add appropriate amount of sea sand and water, grind the plant leaves in a mortar, filter out the plant juice with a 50-mesh silk mesh, and remove the fine sand from the plant juice after standing. Then add appropriate amount of calcium chloride to the clay solution, and then add plant juice to agglutinate like milk, until the supernatant is not colored or turbid, wait 10-20 minutes and then pour out the supernatant. Add distilled water to shake, then rest for 10-20 minutes, remove the supernatant, repeat for 2-3 times, dilute the precipitated part properly and use it as a culture medium.

④ sewer mud medium collects fresh soil from sewer or fish pond, removes large pieces of rubbish, adds the same amount of tap water to stir, and then pours out the supernatant after standing for 30 minutes. This is repeated for 1 or 2 times, remove the suspended matter from the gully mud, sterilize with pressure cooker for 30 minutes, pour the supernatant after cooling, and add appropriate amount of distilled water as the medium.

(3) training method

The chironomid larvae reared with artificial egg collection and artificial medium were inoculated with ①. The larvae with a length of 3 mm and 4 mm were selected by a 60-mesh sieve net and added with distilled water in 1-2 days. After moving the sieve net and rinsing with distilled water, the water was drained and the larvae were inoculated on the medium.

⑦ hydrostatic culture method the common characteristics of the above four media are two-phase medium, that is, the culture substrate is solid clay, milk, plant broken leaves or sediment of sewer mud, and the upper part of the medium is water-based distilled water. When the culture medium is filled with a petri dish with a diameter of 90 mm, the chironomid larvae larger than 3 mm are inoculated in the dish, which is called static water culture. This kind of still water culture can be cultivated until pupation and can be harvested. It has the advantage of easy operation. However, due to the lack of sufficient oxygen, the culture medium is easy to deteriorate, and the yield is far lower than that of running water culture.

In the ⑧ flow culture method, a 33 cm × 37 cm × 7 cm plastic container or a round basin with a diameter of 45 cm was used to put a sand layer with a thickness of 10 mm at the bottom, and then spread clay-milk medium on the dagger surface. Once every 3 days, micro-running water was injected from one end and discharged from the other end, and then the larvae were cultured with running water 24 hours after hatching. Running water can discharge sewage and increase oxygen, and the culture result is better than that of static water culture.

④ larvae whose body length is less than 3mm have not yet completed their mouthparts development, and their resistance to various external environments is weak, let alone the flow speed of 0.1m / s, so another culture method is needed. This method is as follows: in a 500 ml triangular flask, fill half a bottle of water, add 50 ml medium, add the hatched egg into the flask, aerate with bubble stone, 800 cm to 1000 cm per minute. The suitable temperature is 23 ℃ ~ 25 ℃. Under these conditions, the egg block will hatch smoothly, and after 4 days, the body length can reach 3 mm, and then transferred to the running water culture to continue to culture.