Although some people can't help but be a little scared when they hear the term spider, in fact, they are still relatively cute in some ways. For example, when the agricultural harvest is harvested, everyone should not think that in fact, there is a spider here. Anyone who has planted crops will know that spiders are relatively common in the field, and in the summer rice leaves will be hung with large and small spider webs, farmers will mostly weed and sprinkle fertilizer, and the cobwebs will be destroyed, but if you look at it after a while, the spider webs hang up again. So the question is, are the spiders in these fields good or bad? Will their existence affect the crops? Some people will wonder if it belongs to the agroforestry bad insects.
Relationship between spiders and agroforestry pests
Spiders feed on a variety of insects, including many agroforestry pests. Therefore, spiders are actually beneficial insects in the field of agriculture and forestry. And spiders are the natural enemies of agricultural and forestry pests, which help a lot in pest control.
So how many spiders are there in a field or woodland? The Spider Naturalist states, "According to a survey of a woodland soil in the United States, there are 60 to 180 spiders per square meter (an average of 126 spiders), which are 25 to 65 mg in terms of dry weight, an average of 43 mg."
The total dry weight of the animals living in this soil is 842 milligrams, of which spiders account for only 5%, but account for 70% of predatory arthropods. "It can be seen that spiders are important predators among the animals that live in the soil. In nature, spiders have always lived in the form of predators, and their predation on some insects does affect the reproduction of these insects. Therefore, it is also a good hand in the control of agricultural and forestry pests.
The spider's contribution and encounter to agriculture
A famous rice pest, the black-tailed leafhopper, is also known as the black-tailed floating dust. It not only sucks rice sap, but also directly affects the development of rice, and also spreads some rice diseases. This terrible pest to rice is not common in rice paddies and its outbreaks are not common.
There are many reasons, one of which should be spiders that prey on black-tailed leafhoppers. There is a set of data in the Spider Naturalism that in the rice fields of Taiwan, at least sixty kinds of spiders are known, of which the more common two are the ring-like leopard spider and the red-breasted spider, which mainly prey the black-tailed leafhopper. In some surveys, it has been learned that 8% to 25% of adults and 5% to 63% of nymphs in black-tailed leafhoppers are eaten by these spiders, which shows that spiders have a fairly strong control over this pest.
The twill moth is a major pest that harms a variety of crops, especially to legumes and vegetables. After mating, the female twill moth lays a large egg mass of hundreds or even thousands of eggs on the leaf, and the newly hatched larvae will temporarily gather near the egg block to feed on the vegetable leaf, and these larvae happen to be good prey for the dish spider.
The length of the vessel spider is only two or three millimeters, is a small spider, they eat at most three or two larvae at a time, but because of the attack of the vessel spider and frightened by the larvae will scatter everywhere, will also fall to the ground, and because most of the newly hatched larvae can not survive independently, so in the vegetable garden with more vessel spiders, there is rarely a twill nocturnal moth outbreak.
Although spiders play a considerable role in the outbreak of agricultural pests, it can actually be difficult to actively use spiders in pest control. Because many pesticides have a great deal of lethality against spiders. When spraying insecticides for pest control, the mortality rate of spiders often far exceeds that of pests, and if you use pesticides once or twice in a row, it is not easy to see the activity of spiders. This behavior causes the spider's predation pressure to be lifted, and it is more likely to cause subsequent outbreaks of pests.
It follows that the use of spiders and the spraying of insecticides cannot be parallel at the same time, because there will be losses on both sides. On the other hand, the amount of spider predation is actually limited, if other reasons lead to a significant increase in the number of pests, it is impossible to rely only on spiders to control pests, after all, quantitative changes will cause qualitative changes, so only spray pesticides. Spiders are a territorial animal, and when the population density is too high, it is easy to kill each other. Therefore, how to effectively use spiders to control agricultural and forestry pests still needs to be constantly explored.
If you are interested in this aspect, you may wish to take advantage of the summer vacation to take the time to see if the cobwebs in the field are as mentioned above, and may wish to think about how to balance the above problems. Ecological balance is the entire human society and nature to pursue, the food chain in the weak and the strong is also inevitable, each circle has its own rules, so how to maintain balance is an eternal compulsory course. To digress, in this era of survival of the fittest, are you ready to take on the challenges? Regardless of the answer, we should maintain our original intention, constantly cultivate ourselves, and not be eliminated by the natural world and human society.