Ampullaria gigas Spix, also known as apple snail, is a large aquatic snail native to the Amazon River Basin in South America. After being introduced to my country in the 1980s, the snail has become widespread in South my country and Southeast Asian countries due to its strong resistance to stress, miscellaneous feeding habits, amazing fecundity and extremely fast growth rate. Our country is mainly distributed in Guangdong, Guangxi, Fujian, Hainan and other provinces. This snail has the characteristics of direct harm and indirect harm to aquatic crops. The direct harm is that it directly feeds on crop seedlings, causing few or broken seedlings. The indirect harm is that the feeding wounds become a channel for the invasion of various pathogens, inducing the occurrence of various diseases. and popular.

1. Damage characteristics: Hosts include aquatic plants such as rice, wild rice, water spinach, and duckweed, as well as xerophytes such as sweet potatoes near waters. After the eggs hatch, they begin to eat aquatic plants such as rice, especially young parts. The main damage period is from after rice transplanting to before drying. It bites off the main tillers and effective tillers of rice, causing the effective panicles to decrease and resulting in reduced yields

2. Morphological characteristics This snail is a large aquatic snail, and its shell appearance is similar to that of a field snail. It has a spiral shell, which is large, thin, brittle and easy to break. The shell is right-handed, the spiral part is underdeveloped, and the spiral layer is generally 6. The first spiral layer is larger and flatter than the field snail, and looks like an apple, so it is named apple snail. The screw mouth is oval and protected by cuticle. The head and abdominal legs can extend out of the shell and swim for food. The head has a pair of long and short horns, and the eyes are on its short antennae. The color of the snail body varies with the environment and the age of the snail. Young snail bodies are generally gray-white; small snails are golden yellow. There is a large "bubble" in the middle of the back of the first snail layer of the small snails, which rely on floating and breathing; adult snails are mostly dark yellow. Brown, shiny and with several fine vertical stripes. There is a thick lung suction tube on the left side of the snail body. The adult shell is thick, with a shell height of 7cm, and the young shell is thin. The suture line of the shell sinks into a shallow groove, and the umbilicus is deep and wide. Oval, 2mm in diameter, first laid eggs are pink to bright red, with an inconspicuous layer of white powder on the surface. The egg masses are oval in shape and vary in size. The eggs are neatly arranged and the egg layer is not easy to fall off. They are bright red. There are only dozens of small egg masses, and the large ones can reach more than a thousand eggs.

3. Living habits: There are 2-3 generations per year, with overlapping generations. Adult snails and young snails overwinter. The overwintering adult snails begin to mate and lay eggs in mid-April. The overwintering young snails begin to grow and develop in the spring and mature, and they also begin to mate and lay eggs. The female snails do not lay eggs in the water, but crawl 15 meters away from the water surface when laying eggs. Egg masses are laid and adhered to dry places above the pond edge, such as stems, ditch walls, walls, field ridges, weeds and other attachments, as well as stems and leaves of aquatic plants. Egg-laying activities are often carried out at night. Generally, the egg stage lasts about 10 days. The newly hatched snails that have just broken through their membranes can crawl and move around. After falling into the water, they will gather in the shallow water near the pool, or crawl to the moist ground or aquatic plants 2-3 cm above the water surface to swallow the plankton. organisms, etc., to gradually adapt to life in the water. Young snails mature sexually after 3-4 months of development. Except for laying eggs or migrating when encountering adverse environmental conditions, they live in fresh water throughout their lives. When encountering drought, they close their shells tightly and remain motionless for up to 3-4 months. months or longer. Each female snail can lay eggs multiple times. A mature female snail usually lays an egg mass every 5-10 days. The egg mass is pink. Each egg-laying time is 20-90 minutes. After laying, it retracts its abdomen. Foot, fall back into the water. A female snail can reproduce more than 1,000 young snails on average, and can reproduce more than 325,000 young snails in two generations a year, showing extremely strong fecundity. Due to the overlap of generations, after the first peak of spawning at the end of April, there will be a small peak of spawning almost every 10-15 days. After early to mid-November, spawning will stop and gradually begin to enter the overwintering state.

Snails like to live in fresh and clean water. They often live in clusters in shallow water at the edge of the water, or are adsorbed on the roots, stems and leaves of aquatic plants in the water. They can also live out of the water for a short time. Its reliably developed abdominal legs can crawl on the bottom of the pool or attachments, and it can also swim slowly on the water surface, so it is very convenient for feeding.

Apple snails are very sensitive to changes in ambient temperature. When the water temperature is about 28 degrees, they are most active and grow fastest. In summer, they can grow normally even when the water temperature is as high as 34 degrees; but when the water temperature drops below 12 degrees, their activity ability drops significantly, and the water temperature is 8 You can survive the winter safely at -10 degrees Celsius. Apple snails are afraid of strong light and are less active during the day. They feed more on the water surface at night. Their senses are more sensitive and they will sink to the bottom when encountering predators.

The snail has a mixed feeding habit and prefers plant-based feed, so it has a wide range of feed sources. The main feeds include duckweed, green vegetable leaves, melon and fruit leaf peels, bran, wheat sugar, corn flour, etc. They also eat a small amount of dead fish and livestock carcasses. Young snails mainly feed on snails, humus, corn sugar, etc. If the snail population is large in the field, it can harm rice when food is scarce.

The growth and development speed of apple snails is related to environmental conditions, feed feeding, different growth stages and gender. In the high temperature season, the water quality is better, the feed is sufficient, and the growth is fast; on the contrary, the feeding ability decreases and the growth slows down. slow. The growth rate of young snails is faster in the appendix section, and the growth rate slows down relatively when the body weight reaches about 100 grams. In addition, the growth rate of female snails is slightly faster than that of male snails. Under artificial breeding conditions and fed with sufficient feed, the weight of newly hatched young snails can generally reach about 25 grams in one month, about 50 grams in two months, and 100-150 grams in three months. It can reach about 200 grams in six months, and can reach 400-450 grams in one year.