Desert locust once again "grouped" to attack the insecticide industry "star" bio-pesticide amplification
According to media reports, while countries around the world are busy responding to the threat of the new coronary pneumonia epidemic, East African countries are facing a new problem-large-scale locusts are attacking again. The scale of this locust plague is 20 times that of the first disaster at the beginning of the year.
"Since the beginning of the year, the desert locust has swept Africa, West Asia, and South Asia. The Food and Agriculture Organization of the United Nations has again released information that the second wave of locust disasters has caused about 20 million in six countries in East Africa (Ethiopia, Kenya, Somalia, South Sudan, Uganda, and Tanzania). People are in a serious food crisis. In addition, Yemen has also been hit by locusts, and 15 million people in the country are facing the same situation. "Zhang Zehua, a researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences and a scientist in the national forage industry technology system, said in an interview with the Science and Technology Daily reporter .
Large-scale locust disasters have occurred again in many countries, and Spodoptera frugiperda also threatens our country's food security. In this fight against pests, in addition to traditional chemical pesticides and other pest control measures, biological pesticides are gradually becoming a rising star in the insecticide industry.
Feeding fungi to make locusts suffer from "flu"
So, what technologies are used in the design of biological pesticides, and how do these pesticides eliminate locusts?
"Biological pesticides refer to living organisms and their metabolites, including microbial pesticides, plant-derived pesticides, natural enemy organisms, etc. At present, among the biological pesticides for controlling locusts, more environmentally friendly microbial pesticides, including fungi, Bacteria, viruses, protozoa, etc. "Tu Xiongbing, an associate researcher at the Institute of Plant Protection of the Chinese Academy of Agricultural Sciences and Secretary-General of the National Innovation Alliance for Grassland Biological Disaster Prevention, told Sci-Tech Daily reporters.
These microorganisms originate from nature. "For example, Metarhizium anisopliae, which we commonly use now, is an important entomogenous fungus, which is extracted from the body of locusts suffering from 'influenza'. Compared with chemical pesticides, many biological pesticides have a slower effect. It usually takes 1 to 2 weeks to start working on pests. "Tu Xiongbing said.
In order to increase the speed and effectiveness of the prevention and control of these agents, researchers have used aerospace mutagenesis, genetic engineering, molecular breeding and other technologies to increase their virulence against locusts.
Tu Xiongbing said that locusts suffer from "influenza" after eating or contacting these fungi, and this "flu" will continue to reduce the reproduction rate, attack power and lifespan of locusts. Judging from the current statistics, the control effect of this control method can reach 8 to 10 years at the longest. There are also methods for natural enemies to control locusts. For example, in Inner Mongolia, the use of chickens and ducks to control locusts; in western Xinjiang, artificial nesting to attract pink starlings to control locusts has been successful, and has become a model for the prevention of locusts by natural enemies in local areas.
Has been used to control cotton and vegetable pests
"No single technology can solve the problem of locust disasters, so we must combine biological control, chemical control, and ecological control measures to achieve long-term control of pest populations." Zhang Zehua analysis, especially in medium and high density areas, can use biological pesticides Mainly through continuous control measures, these microbes form a disease epidemic in the dense locust population, through migration and carrying each other, to achieve continuous control of locusts, so that the disaster does not spread.
In addition to biological pesticides against locusts, what biological pesticides are scientists still developing?
"In addition to fungi, bacteria and other microbial anti-locust insecticides, there are many types of biological insecticides currently on the market, including Bacillus thuringiensis, viruses, and plant-derived pesticides." Tu Xiongbing introduced, among them, Bacillus thuringiensis Insecticides, also known as Bt insecticides, are currently the most successful insecticides in the research, development and application of biological pesticides, accounting for more than 90% of the total biological insecticides, and can control more than 150 lepidopteran pests.
"Bacillus thuringiensis can be used not only for pest control, but also for transgenic breeding techniques. For example, the successful breeding of Bt transgenic cotton has effectively controlled the harm of cotton bollworm, and it has been widely applied in cotton growing areas in China." Tu The male soldier said that nuclear polyhedrosis virus played an important role in controlling vegetable pests such as beet armyworm, Spodoptera litura. There are also plant-based insecticides such as azadirachtin, matrine, rotenone, which have good control effects on different target pests such as aphids and diamondback moth.
Low toxicity or non-toxic, long duration of action
What are the main advantages of biological pesticides compared to chemical pesticides?
Zhang Zehua said that in comparison, biological pesticides have three major advantages, one is long validity. Compared with chemical pesticides, biological pesticides are less toxic or non-toxic, and have a long duration of action. For example, from 2003 to 2005, Taipusi Banner in Xilinguole League, Inner Mongolia, used Metarhizium anisopliae to control locusts for three consecutive years. Until 2016, surviving Metarhizium spores could still be detected in the soil. No locusts occurred in the area for 10 consecutive years.
Zhang Zehua pointed out that biological pesticides also have a major advantage, that is, the target is good and the selectivity is strong. They are only effective for one or one type of pests, and have no effect on non-target pests. They also have effects on humans, birds, fish, silkworms, etc. harmless. In addition, residue-free and environmentally friendly is also one of the advantages of biological pesticides. The dosage of bio-pesticides is relatively small, and pests are not easy to develop drug resistance. At present, there is no report on the resistance of pests after the use of bio-pesticides. And they are derived from soil, plants or insects in nature, so they can avoid the environmental pollution problems caused by chemical pesticides.
Zhang Zehua told reporters that taking microbial control of locusts as an example, before 2000, the average annual area of grassland locusts in China exceeded 300 million mu. After adopting biological control measures such as Metarhizium anisopliae, the average annual area of grassland locusts in China is now controlled at 120 million. Within acres. And the proportion of biological control has increased from 15.4% in 2003 to 60% now, making a positive contribution to protecting the grassland ecological environment.
"After practical tests, this biological control measure is harmless to the environment, widely accepted internationally, and has been widely promoted and applied in China. It has also begun to go abroad to serve Kazakhstan, Mongolia, and Laos. Wait for countries along the Belt and Road. "Zhang Zehua said.
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What caused the Desert Locust outbreak year after year
"The rains brought by the two cyclones in 2019 provided favorable conditions for the propagation of locusts. The large-scale rainfall in March this year prompted the rapid incubation of locust eggs, which was an important cause of the desert locust outbreak. However, the natural resources were disorderly developed and felled. Trees are used as fuel, burning wasteland, reclamation, abandoned farming and leaving idle, leading to the destruction of the ecological environment, which is the main reason for the desert locust outbreak. "Zhang Zehua analysis.
The wind field characteristics of the African continent provide unique conditions for the desert locusts to move. Every year, between the main breeding areas, from the Red Sea, the Horn of Africa to the Sahel region, the center of the Sahara Desert, and the Nile River Basin, Tigris River, The two river basins of the Euphrates and the Indus river basins have circulated and moved, making desert locusts spread all over the African continent.
"Insufficient monitoring and timely prevention and control have led to successive outbreaks of desert locusts. Due to the ongoing wars in Africa, insufficient monitoring technical strength, and poor communication of information, timely warnings cannot be provided." Zhang Zehua said that there are more desert locust residues in 2019. This year, the outbreak planted “mines”, and the first wave of locust disasters failed to be effectively prevented. The second wave of disasters mainly came from the first wave of desert locusts laying large numbers of eggs. The locust populations overlapped from generation to generation. There are both adults and nymphs in the family. As the locust worm is unearthing, the eggs are still hatching, the threat is getting bigger and bigger, and the control is becoming more and more difficult. The desert locusts were allowed to reproduce for two generations without restraint, which led to the locust plague that would not be encountered in 2020.
Because disasters have already formed, there are not many options for prevention and control, excessive use of chemical pesticides, mass killing of natural enemies, and desert locusts that have lost their natural control have become outbreaks.