The regularity of ants entering and leaving the nest every day

In recent years, imported Solenopsis invicta has occurred from time to time in Guangdong, Fujian, Hunan and other provinces in China, which has brought serious impact on social life and economic development. The Ministry of Agriculture attached great importance to the prevention and control of Solenopsis invicta, and issued an announcement on June 5438+1October 65438+July 2006, which designated Solenopsis invicta as a national and national plant quarantine pest, and formulated and launched the Emergency Plan for the Prevention and Control of Solenopsis invicta. Because red imported fire ants have been colonized in the United States for more than 70 years, they have basically mastered the occurrence law and control technology, and their economic and social impact has been controlled. This paper introduces the occurrence and control of red imported fire ants in the United States, hoping to provide some reference for the control of red imported fire ants in China.

The occurrence history of 1 [1, 2]

At present, four species of fire ants have been found in the southeastern border of the United States. Among them, the tropical fire ant (Solenopsis geminataFabricius) and the southern fire ant (S. xyloni McCook) are considered as local ants. The other two species are invasive black fire ants and red fire ants. The black fire ant (Solenopsis richteriForel) invaded the United States around 19 18, while the red fire ant (Solenopsis invicta Buren) invaded the United States in the late 1930s. These two fire ants may have been invaded by cargo ships with ballast soil. A few years before the invasion of red fire ants, the invading black fire ants slowly spread to neighboring counties and towns in Alabama and Florida. Solenopsis invicta is a more invasive species, which is much more invasive than Solenopsis invicta and spreads very fast. By the time of official investigation by USDA 1 in 1953, the invading fire ants had occupied 102 counties in10 states. Today, the invasive red alien fire ants spread all over the southeastern United States 13 states, replacing two native species and invading black alien fire ants. At present, the invasive black fire ants are only distributed in northeast Mississippi, northwest Alabama and some nanbu county in Tennessee.

Invasive fire ants naturally spread to new places through marriage, group movement or drifting during periodic floods. However, the rapid spread of invasive fire ants is achieved through human behavior. The spread of these ants is due to the transplanting of turf and the transportation of ornamental plants. 1953 The spread of invasive fire ants attracted the attention of the United States Department of Agriculture, because the direct relationship between commercial plant nurseries and invasive fire ants had been established at that time. In response to the growing public pressure, the US Congress allocated $2.4 million in 1957 for control and eradication. 1On May 6th, 958, the federal quarantine regulations formulated regulations on the transportation of seedlings, turf and other articles. However, at that time, the invading fire ants had already entered eight southern states. Although the speed of communication has been greatly slowed down by strengthening control, communication has continued to this day. In recent years, red imported fire ant communities have been found in California in the west and Kansas and Maryland in the north.

2 Biological characteristics and harmfulness [1, 2,4]

2. 1 The biological characteristics of fire ants belong to Hymenoptera, Formicidae and stinkbug. Like other ants in Formicidae, it is a social insect, consisting of 1 egg, young ant, worker ant and queen ant. Among them, the red imported fire ant 1 community may have 1 ~ 60 queens, which is the most serious occurrence and harm at present. The queen ant can live for 6-7 years, and she lays about 2,000 eggs every day in her life. It takes 20-45 days for fire ants to mature from eggs. Larger worker ants appear within 30 days after hatching, and thousands of worker ants occupy the whole community within 6 months, forming a clearly visible ant pile. At the mature stage, the fire ant community ruled by 1 single ant queen can accommodate more than 250,000 fire ants.

Solenopsis invicta can only survive in areas where the annual minimum temperature is above-12℃ and the annual rainfall is above: 250mm, and it will not happen in areas that are too cold and dry.

The obvious feature of 1 of fire ant community is the formation of soil nests or mounds. This mound consists of 1 piece of excavated soil.

1 hard waterproof shell conical vault.

The mound has an average diameter of 0.40m and a height of 0.25m.. 1 The mound may exceed 1 m and its diameter exceeds 1.5 m on the land that is difficult to cultivate. Usually, there is no opening on the surface of the mound, and the passage about 25 ~ 50 mm below the surface of the mound can allow predatory worker ants to enter and exit freely. Mounds have three functions: 1) to provide a flight platform for wedding flights; 2) Raise the community above the groundwater level on the water-saturated surface; 3) As a 1 passive solar collector, it provides warmth for the residential area in cold winter. Although mounds are important to 1 community, they are not essential to the survival of the community. As long as there is a dark place with 1 sufficient humidity and food supply, fire ants can nest in various places, such as rotten wood, walls of buildings, sidewalks or under roads, cars, dried cow dung and so on.

2.2 Harmfulness

2.2. 1 The most notorious fire ants are their stinging behavior. They respond very quickly and positively to any behavior that interferes with their communities and food sources. 1 Fire ants can continue to sting people even if the venom is used up. At first, stings can cause local intense burning pain (hence the name "fire ants"). In the following 24 ~ 48h, 1 white pustules were formed at the bite. This pustule is only a reaction after being bitten by two invading fire ants, but not after being bitten by local fire ants. If not kept dry, these pustules may lead to secondary infection and leave permanent scars. The venom of a few people bitten by fire ants is very sensitive and reacts strongly: chest pain, nausea, dizziness, shock, and in a few cases, coma. Death after being bitten by fire ants is also very rare.

2.2.2 Fire ants that destroy the ecology are omnivores and can feed on almost any plant or animal, although insects seem to be their favorite food. In rural habitats, fire ants have a serious impact on terrestrial animals, from insects to reptiles, birds and mammals. The invasion of fire ants has greatly damaged the local ecological structure. If fire ants are allowed to establish communities in specific places, the number of vertebrates such as voles, egg-laying snakes and turtles will be reduced by at least 2 times. In some cases, the invasion of fire ants made some species completely extinct from the ecosystem.

The invading fire ants not only reduced the number of animals, but also fed on plants. Fire ants will eat young saplings and seedlings. They destroy flower buds and growing fruits and feed on the seeds of 139 local wild flowers and weeds. Secondly, fire ants will take care of homopteran pests of several plants, such as aphids and scale insects. In addition, there are signs that their own activities on plants will reduce the ability of pollinators to pollinate successfully.

In agriculture, fire ants have been proved to harm 57 kinds of crops. Fire ants will devour the seeds sown by some crops (such as corn, sorghum and soybeans) and the buds and fruits of other crops (such as citrus and okra pods). Fire ants can also penetrate the tubers of potatoes, seriously damaging underground peanuts. When fire ants surround the trunk and trunk, young citrus trees and walnut trees will be destroyed. In the dry season, fire ants will do more harm to plants because they need alternative water sources. In drip-irrigated fields, fire ants build anthills on sprinklers to reduce or stop the flow of water to crops. In addition, the emergence of fire ants will also affect agricultural management and increase labor costs.

2.2.3 Fire ants that affect economic and social life build nests on the walls of urban homes or offices, and build communities under sidewalks and driveways. Once the habitat is abandoned, collapse will cause cracks, and in some cases even lead to the complete collapse of some building structures; The appearance of fire ants will delay outdoor activities in courtyards, parks and school playgrounds; Invasion of houses will threaten the safety of children and adults; Burglary is especially common during heavy rain or flood; Fire ants sting car drivers, causing traffic accidents; Fire ants will also be attracted by current, which will damage heat pumps, air conditioners, telephone booths, converters, traffic lights, oil pumps and so on.

In addition, the occurrence of fire ants affects the normal trade and tourism exchanges between regions and countries, so it also

Have a certain influence on politics.

3 control method [1, 2, 3, 4]

3. 1 Quarantine Although the occurrence of fire ants is quite common in the United States, the quarantine of flowers, plants and seedlings is still an important and effective means to control the spread in areas (states) that have not yet occurred. In the United States, many states with climate conditions for fire ants have implemented strict quarantine measures, so far no fire ants have occurred.

3.2 Chemical control

3.2. 1 Available pesticides The pesticides currently used to control fire ants in the United States include fipronil, indoxacarb, mirex hydrazone, boric acid, abamectin, diazinon, chlorpyrifos, pyrethroid, dioxygen, etc.

3.2.2 Usage

3.2.2. 1 single pier control method

3.2.2. 1.65438+ Be careful not to disturb the mound before soaking, because any trouble will warn the community to take the queen ant deeper into the mound and not to touch chemicals.

3.2.2. 1.2 bait method If bait is used, bait should be cast at a distance of 0.3 ~ 1.0m from the mound rather than on the mound itself. Bait method is slow to take effect, but it is usually safe, cheap and lasts for a long time.

3.2.2.2 bait propagation method

Baits made of corn flour, soybean oil and slow-release pesticides or insect growth regulators were scattered in the ground. Workers found the bait and transported it back to the community. The drugs spread throughout the mound, affecting all members of the community. Bait propagation has several advantages: different from the single hill control method, the community does not need to be located first and then treated, and the predatory workers quickly find scattered particles and bring them back to the rest of the fire ants in the nest; Bait propagation method is much more labor-saving than single hill control method, and the cost per mu is also less. However, the bait propagation method also has its disadvantages: it is not specific to fire ants; The bait will deliquesce in water and will not be found by fire ants; The feeding of bait is also affected by temperature.

3.3 Biological Control Law

3.3. 1 Parasitic fleas are parasitic on several ants, some of which are considered to be subject-specific of fire ants. Adult fleas and flies lay eggs on worker ants who go out hunting, and maggots move to the ant's head and feed there, which eventually leads to the ant being beheaded. As interesting as this phenomenon, the main function of these fleas and flies is to prevent ants from preying. When fleas exist, worker ants will retreat to the community to prevent fleas from laying eggs on their heads. This destructive reaction to fleas and flies limits the ability of the community to feed itself, which may make the "arena" flatter and make other ants more competitive than fire ants.

3.3.2 Parasitic ants (Labauchena)

Dagerrei is an ant that parasitizes the queen of fire ants. It causes the workers of fire ants to feed the eggs of parasites, thus damaging the larvae of the community itself. Interestingly, S. dagerrei has no working class and only breeds queens and males. The existence of this parasitic ant weakens the sex ratio of community growth and reproduction. The queen of S. dagerrei enters the fire ant community and parasitizes on the fire ant queen. Previous studies have shown that this parasitic ant inhibited the fire ant queen and its spawning, which led to the collapse and eventual extinction of the fire ant community.

3.3.3 Some arthropods, fungi, bacteria, nematodes, viruses, microsporidia, etc. It may also have a certain control effect on fire ants.

So far, none of these natural enemies of fire ants has been fully considered to have a real inhibitory effect on the number of fire ants. In all possible cases, parasites, predators and viruses will unite to reduce the adaptability of fire ant communities. Reducing the vitality of fire ant community may lead to high mortality under harsh conditions, thus improving local ant varieties and their competitiveness.