Biocontrol of Bemisia tabaci

Bemisia tabaci (Gennadius), also known as sweet potato mealybug and cotton mealybug, is one of the important pests in tropical and subtropical regions. Since the mid-1980s, due to the emergence and widespread dissemination of new biotypes (Type B) and the rapid development of drug resistance, it has become a major pest of plants in many countries such as cotton, vegetables, and garden flowers. It is caused on average around the world every year. The economic loss exceeds 300 million U.S. dollars, and the losses caused by the U.S. in 10 years exceeded 1 billion U.S. dollars. In recent years, the dynamic occurrence of the whiteflies population in China has changed significantly, and B-type Bemisia tabaci has aggravated the hazard and spread year by year. In the treatment of B. tabaci, biological control is a very important control method. The natural enemies of B. tabaci are abundant in resources. Scholars from various countries have done more work on the research and application of natural enemies and have achieved certain results in production practice. 1 Research and application of predatory natural enemies There have been reported about 114 species of predatory natural enemies of B. tabaci (9 orders and 31 families), including 94 species of ladybugs, 25 species of predators, 14 species of grassland, and 17 species of prey. . Although there are many types of natural enemies, only a few are actually used, and most of them are polyphagous predators. Dean et al. pointed out that polyphagous predators have behavioral plasticity and can increase their predation by feeding on a variety of prey species, allowing the population to multiply. 1.1 The ladybug (Delphastus catalinae) is native to the U.S. and is a predator of the whitefly, and has been successfully used in the control of cotton and Christmas hazelnuts in California and Florida. And has been introduced into Europe and Fujian of China. Indoors, the black ladybugs have the highest fertility to feed on whiteflies eggs, while the fecundity of the mealworms on the field is greater. When the density of whiteflies is low, other prey such as red spiders may be taken, but the breeding population cannot be maintained. The black ladybug is able to prey on the whitefly nymph that has been parasitized, but it can be gradually discriminated and eaten as an unparasitized nymph as its development progresses. Black ladybugs have been produced and sold by a number of companies and the recommended release of greenhouse crops is 1 adult/1.39-9.29 m2. It has been reported that the potential of Nephaspis oculatus to prey on Bemisia tabaci is low, but its search power is obviously stronger than that of B. sinensis, so when the density of whiteflies is low, the population density of this species is higher. . 1.2 Predatory macropods Macrolophus caliginosus is a polyphagous predator who eats eggs, nymphs and adults of B. tabaci, and is more likely to eat eggs of whiteflies. When the density of whiteflies is low, some of them can also feed on certain flower plants. Maintain the continuation of its population. In Europe, blind lice have been widely used to control B. tabaci and Trialeurodes vaporariorum. Since the blind locust can establish a population for more than one month, simultaneous release with Encarsia Formosa is a key measure to keep the population density of the whitefly in the greenhouse low. It has been applied in some countries in the Mediterranean region. Rabou reported that 3 consecutive ticks were released from the eggplant in 2 heads/strain. After 1 month, the whitefly population could be effectively controlled; the release was 0.5-1 head/m2 every 2 weeks. Once released once a week, the citron was also able to effectively control the hazards of tomato mealybugs in the greenhouse. In addition, Typhlodromus swirskii and Euseius scutalis used B. tabaci to feed on whiteflies, and its intrinsic radon increased more vigorously than B. tabaci, and it was able to inhibit the growth of B. tabaci population in monoculture crops grown in greenhouses. There is value for further use. 2 Research and Application of Parasitic Natural Enemies B. tabaci is rich in parasitic natural enemies, including Encarsia, Encarsia, Amitus, and Metaphycus Many species. There are 19 kinds of preliminary investigation records in China (mainly belonging to the genus Nympha and Oleoptera). 2.1 Enphematidae Species of this genus are mostly single-parasitic. A few are heavy or parasitic. Adults produce eggs in the body. As the citron was able to successfully control the greenhouse whitefly, many scholars at home and abroad have done a lot of research and report. There have been comprehensive discussions on the biological characteristics of adult bees and larvae, the population dynamics of interactions between the bee and whiteflies, and the commercial applications in the greenhouse. The study on the potential of control of Bemisia tabaci in different temperatures showed that it is feasible to use parasitic wasps within the range of 16-28°C. Barro et al. reported on the control of five parasitoids such as Lysimaea cinerea on B. tabaci. The effects of host plants on parasitoid behavior were also discussed. Rabou evaluated the control effect of the citrifolia wasp on the whitefly, with a parasitism rate of about 83%. In addition, comparative tests showed that the ability of the Beltsvilla population to parasitize Bemisia tabaci was better than that of the Koppert population. When mixed with whiteflies and whiteflies, the control potential of the Beltsvilla population is better. Encarsia pergandiella is also a reported parasitic wasp. Schuster et al. and Liu et al. studied the nymphal stage of B. tabaci and the effects of host plants on their development and parasitism. The results showed that the bee could parasitize whiteflies of all ages, but the parasitism rates were highest for 3 and 4 instar nymphs. The type of crop has little effect on its development duration. Hunter research found that when the number of unparasited whiteflies is equal to the number of parasites that have been parasitized, the eggs produced by the adult of the bee are mainly male; if the number of non-parasited whiteflies predominates, the offspring are mostly female. . This phenomenon is conducive to the stability of the host-predator system. 2.2 P. ostracodus This species of genus is a single parasitism, and most of them are parthenogenetic females, and a few can also produce parthenogenetic females. Adult bees spawned under the abdomen of the 1st instar nymph of Bemisia tabaci. After the larvae hatched, they penetrated into the host and fed the host solution as a nutrient. Er.mundus and Er. eremicus are two species that are widely used in research. Er.mundus has the highest parasitic rate and survival rate and eclosion rate of the second instar nymph of Bemisia tabaci, and the development time of 1st instar nymphs. longest. Headrick et al. studied the reproductive system and reproductive parameters of Er. eremicus, and used the life table method to evaluate its control potential on two host plants. Er. eremicus can both parasitize the whitefly and parasites in the greenhouse, while Er.mundus cannot parasitize the greenhouse. Hoddle et al.'s study on Er. eremicus controlling greenhouse fume on Christmas red shows. Two release technologies (high-low and low-high release strategies) have various effects on the net fecundity and parasitism rates of whiteflies. It has also been reported that the use of the bee to control tomatoes and peppers in places such as southeastern Spain The area of ​​Upper Whitefly has reached 500hm2 and 1000hm2 respectively. 3 Research and application of entomopathogenic fungi The most reported pathogens of B. tabaci are mostly Myxosporidium species, including Verticillium, Paecilomyces and Aschersomia. Some of the kinds. P. fumosa roseus is widely distributed. Can infect a variety of insects. The infection rate of B. tabaci against B. tabaci was very low. The infection rate was high for nymphs, especially young instar nymphs, and the infection rate for adults was low. However, under the proper conditions, it could spread in adults. The bacteria in the United States, the Indian subcontinent and other countries in the greenhouse and field populations of Bemisia tabaci can cause epidemics. In the United States, it has been used as a microbiological insecticide for the control of fusulin, poinsettia and other whiteflies. It is recommended that the rejection is 3 kg/hm2, applied once every 5-7 days, and used continuously for 2-4 times. Verticillium lecanii is an entomopathogenic fungus of parasitic aphids, aphids, and whiteflies. The infection rate of B. tabaci eggs is extremely low, but the infection rate is high for all ages of nymphs. Repeated use of the bacteria in the greenhouse (4 times per week) can significantly reduce the population of whitefly on the melon. In the area where the whiteflies and whiteflies occur in the southern part of Spain, local residents released a combination of Er. eremicus and Orius laevigatus, which combined with the control of Verticillium lecanii, achieved good control. BEAUVERIA BASSIANA can parasitize a variety of insects, and is a major parasitic nymph, especially young instar nymphs. And has shown greater control potential in greenhouse and field experiments. It has also been reported that Aschersonia aleyrodis and A. placenta have high infection rates against B. tabaci, and they are easily infested with whitefly nymphs and can also cause fly aphids. Adult and egg epidemics occur. 4 Conclusion The biological control of Bemisia tabaci has so far had a history of 30 years, but the investigation, collection and research work on the resources of natural enemies of Bemisia tabaci has just begun. Although the world’s research on the biological control of Bemisia tabaci has been fruitful, industrialized production has been achieved for the citrifolia vespa, black ladybug, grass ridge, and blind pupa, but in terms of the natural resources of the whiteflies and their control needs, There is still much work to be done. For example, the research and development of the natural enemies protection technology of B.tabacii; the interactions between natural enemies, hosts and host plants, the interaction mechanisms between different natural enemies and different natural enemies, and the application of natural enemy population complexes. ; Evaluation of the relationship between B. tabaci biocontrol technology and its transmission of viral diseases.

Catalyst refers to a substance which can change the reaction speed in a chemical reaction and whose composition and mass remain unchanged after the reaction. The catalysts that speed up the reaction are called Positive Cata-lyst and the slower ones are called Negative Cata LYST or moderators. Generally speaking, the catalyst is to correct the catalyst. These catalysts are widely used in industry, especially in organic chemical industry. They are of great significance, for example, catalysts are needed for the preparation of sulfuric acid by contact method, the hydrolysis of synthetic ammonia, esters and polysaccharides, and the hydrogenation of oils and fats. Commonly used catalysts are metals, metal oxides and inorganic acids. If the catalyst is a solid, the reactant is a gas, forming a heterogeneous catalytic reaction, this catalyst, sometimes called a catalyst or contact agent.

Auxiliaries refer to the industrial and agricultural production, especially chemical production, in order to improve the production process, improve product quality and output, or give the product a unique application performance, usually need to add some auxiliary chemicals. It is a kind of important auxiliary raw materials in chemical production, which can give the products special properties and improve the use of finished products, accelerate the chemical reaction speed and improve the yield of products, save raw materials and improve the processing efficiency. It is widely used in chemical industry, especially in organic synthesis, synthetic material processing and petroleum refining, pesticides, pharmaceuticals, dyes, coatings and other industrial sectors. By use, it can be divided into synthetic auxiliaries and processing auxiliaries. Auxiliaries used in the synthesis and polymerization of resins, fibers, rubber and other monomers are called synthetic auxiliaries, including catalysts, initiators, solvents, dispersants, emulsifiers, polymerization inhibitors, regulators, terminators, etc. Auxiliary chemicals used in the manufacture of rubber, plastic products and in the spinning and spinning of chemical fibers are called processing aids, including plasticizers, heat stabilizers, antioxidants, light stabilizers, flame retardants, foaming agents, lubricants, demoulding agents, vulcanizing agents, accelerators, softeners, anti-scorching agents. Agents, surfactants, oils, fillers and so on. Many of these Additives are dangerous chemicals, such as diphenyl peroxide, azodiisobutyronitrile, hydrogen peroxide-ferrous blue, alkyl aluminum, titanium chloride and other initiators, catalysts are inflammable and explosive materials, should be stored and transported in accordance with the relevant provisions of the Regulations on the Safety Management of Chemical Hazardous Goods. Management and use.

Catalysts And Auxiliaries

Dyeing Auxiliaries,Dimethyl Silicone Oil,2-Phenoxyethanol 99%,Sodium Prop-2-Ene-1-Sulfonate

Shandong Chenyi Environmental Protection Technology Co.,Ltd ,

Posted on