Benefits and harms of spiders

Arthropoda , Arachnida , Araneida , Araceida , is a generic term for all species of the order Araneida or Araneae. It is found worldwide except Antarctica. It spreads from sea level to 5,000 meters above sea level. Both are terrestrial. Body length 1 to 90 mm. Spiders are both beneficial and harmful to humans, but in terms of their contribution, they are mainly beneficial insects. Spider body lengths range from 0.05 mm to 60 mm. The body is divided into head, chest and abdomen. Some species have breastplates on the back of the cephalothorax, and the front of the cephalothorax usually has 8 single eyes (there are also 6, 4, 2, 0), arranged in 2 to 4 rows.

benefit

Spiders are both beneficial and harmful to humans, but in terms of their contribution, they are mainly beneficial insects. For example, in farmland, spiders prey on mostly crop pests. At the same time, in many traditional Chinese medicines, there are records of the use of spiders into medicine, so it is of great significance to protect and use spiders. In particular, the protection of rice field spiders has three major advantages: one is to effectively stabilize the balance of biological populations; the second is to reduce the chemical pesticide residues of rice and ensure the safety of people and animals; third, to reduce production costs, can obtain increased production and income. Therefore, in the prevention and control of crop diseases and insect pests, it is advocated to use high-efficiency and low-toxicity pesticides, carry out biological control, and protect natural enemies.

Spiders are diverse, widely distributed, adaptable, and can live or form webs on the surface of the soil, in the soil, in the trees, between grasses, under rocks, caves, watersides, low-lying lands, bushes, mosses, inside and outside houses, or inhabit freshwater (such as water spiders), coastal lake belts (such as lake spiders). In short, there are traces of spiders in water, land and air.

Harm

Poisonous spiders pose a threat to human safety, and some spiders can also harm crops. Spiders if the abdomen is red is poisonous, how many real poisonous spiders, there is no exact statistics, the world's more toxic, there are bulbous spiders of the Mediterranean black widow spider, the brown flat beetle of the beetle family, the Australian funnel spider of the warty spider family, the black-bellied ctenopod spider of the ctenopod family, and the Australian bird-catching spider of the bird-catching spider family. According to statistics, there were 1726 cases of lactation by Lathroclectustus in the United States between 1959 and 1973, and 55 deaths. In the genus Line Spider, Bird Catcher Spider, the bite wound is large and deep, and the bite wounds of the tarantula genus and the garden spider genus are lighter. Phoneutria spider toxin is very strong, to 20 grams of mice as a test, from the intravenous injection of 0.006 mg of toxin, 2 to 5 hours of death, female spider toxicity is much stronger than male spider toxicity, male spider will not give people a lethal amount of toxin. Because spiders are very venomous, in Brazil, the eastern Mediterranean, Yugoslavia and other countries, spiders are feared.

The most harmful to crops are the red spiders:

Red spiders, also known as fire dragon worms, are red spiders that are harmed on jujube trees, mainly cotton red spiders and alfalfa red spiders. Cotton red spider belongs to the order tick mites, leaf mites, also known as cotton mites or two-point leaf mites, commonly known as "fire beads", "fire dragon". In recent years, red spiders have occurred severely in many jujube areas. It harms the leaves, sucks chlorophyll particles and cell fluid, inhibits photosynthesis, reduces nutrient accumulation, and yellows the leaves in severe cases, causing early leaf fall and fruit fall, affecting yield. The hosts of red spiders are mainly cotton, wheat, beans, corn, millet, sesame, melons, eggplant, dates, mulberries, peaches, sunflowers and weeds in the summer solstice grass and small spiral flowers. The harm of the red spider to the northern jujube area is heavier than its harm to the southern jujube area.

The number of occurrences of red spiders each year varies depending on climatic conditions. In the northern jujube region, more than 10 generations occur in one year. The breeding method is mainly intersex reproduction, and each female adult mite lays an average of 6 to 8 eggs per day. In mid- and late October, female mites migrate to bark crevices, weed rhizospheres and under soil blocks to overwinter. At this time, the mite body is orange-red, and the dark spots on the side of the body disappear. In late April of the following year, the wintering red spider began to become active, and in late May it began to become harmful. In June, the weed hosts mature and wilt in early spring, and after the wheat harvest, the environment changes, the temperature rises, and the red spiders move to the jujube trees in large numbers, and gradually spread to the top and periphery of the trees, with the most serious damage from June to August.

The activity of the red spider is related to environmental conditions. The optimal temperature of its activity is 25 °C ~ 35 ° C; the optimal relative humidity is 35% ~ 55%. High temperature drying is the main condition for the rampant occurrence of this mite, and different farming systems affect its occurrence. For example, if the former stubble crops are beans, millet, corn and cotton, the overwintering base of the insect population is large, and the occurrence of the following year is more serious.