Rodent Damage and Control Methods in Hami Grassland of Xinjiang

Nurlan HASEM

Hami City Locust and Rodent Prediction and Prevention Station, Hami 839000, China

Abstract Since 2002, Hami City, Xinjiang Province, has implemented "construction project of rodent-free demonstration area". Artificial eagle frames are installed on the grassland to control rodent damage, receiving remarkable control effect. The rodent density in the treatment area is below the threshold of hazard. Moreover, the implementation of the project increases the grassland biomass and improves the vegetation coverage, receiving good economic, ecological and social benefits.

Key words Hami grassland; Rodent damage; Prevention and control technology; Attracting eagles to control rodents

1 Introduction

Rodent damage is one of the most severe biological disasters in grassland, which is an important factor leading to grassland degradation, desertification and soil erosion, seriously threatening the sustainable development of grassland animal husbandry, grassland biodiversity and healthy development of grassland ecological construction. In the past, chemical pesticides were used to control grassland rodent damage in Hami City, and acute rodenticides were first used. Chemical pesticides not only killed grasshoppers and produced secondary poisoning, but also killed the natural enemies of rodents and polluted the ecological environment of grassland. These highly toxic acute drugs were banned in the late 1970s. So far, anticoagulants and biological pesticides such as creotoxin C and D have been gradually used. Comprehensive prevention and control is carried out by setting up artificial eagle frame and ecological control. The prevention and control of rodent damage has gradually developed from single chemical control to comprehensive control and ecological management, and entered a new stage of laying equal stress on deratization and ecological and environmental protection.

2 Basic situation of Hami grassland

The natural grassland area in Hami reaches 4.193 5 million hm2, accounting for 29.4% of the total land area. The available natural grassland area is 3.900 7 million hm2, accounting for 93% of the total natural grassland area. According to the damage to forage grass caused by grassland rodents, the economic value of prevention and control, the types of grassland in different regions, the population composition of main rodent pests, and the characteristics of natural environment, the whole city could be divided into 5 distribution areas of grassland rodent pests and 14 hazard areas of rodent damage. Grassland rodent damage mainly occurs in China-Mongolia border area, low mountainous and hilly area of Barkol, mountain and desert steppe of east Tianshan section and oasis residential area of Hami basin.

The animal husbandry production accounts for a large proportion in Hami City. Both Barkol and Yiwu counties are animal husbandry counties. The animal husbandry in Hami City is dominated by grassland animal husbandry. The meadows in Hami City are also divided into spring and autumn meadow, winter meadow and summer meadow, and rodent damage is usually severe in spring, autumn and winter meadow. According to the investigation ofRegionalDivisionofDominantGrasslandRodentSpeciesinHamiRegionofXinjiang, Hami City is one of the areas with severe rodent damage in Xinjiang. The area of rodent damage in the grassland of Hami City is 526 700 hm2, accounting for 14% of the available meadow area.

2.1 Main rodents and rodent damage areaThere are 25 species of rodents belonging to 17 genera and 5 families in Hami City. The main species of rodents harmful to agriculture and animal husbandry includeEolagurusluteus,Rhombomysopimus,Laguruslagurus,Merionestamariscinus,Merionesmeridianus,Ellobiustalpinus,Rattusnorvegicus,Cricetulusmigratorius,Dipussagitta,Musmusculus,etc.According to the damage to forage grass caused by grassland rodents, the economic value of prevention and control, the types of grassland in different regions, the population composition of main rodent pests, and the characteristics of natural environment, the whole city could be divided into 5 distribution areas of grassland rodent pests and 14 hazard areas of rodent damage. Among them, there are 8 harmful regions with an area of 445 000 hm2in Barkol County, 2 harmful regions with an area of 34 000 hm2in Yiwu County, and 4 harmful regions with an area of 175 300 hm2in Hami oasis. Grassland rodent damage mainly occurs in China-Mongolia border area, low mountainous and hilly area of Barkol, mountain and desert steppe of east Tianshan section and oasis residential area of Hami basin.

2.2 Main harms of grassland rodentsFirst, the rodent’s digging and burrowing activities reduce the coverage area of forage grass growth and reduce grassland productivity. The digging activities of rodents pile a large amount of subsoil onto the ground to form mounds that will cover the meadows. There are so many continuous mounds that not even a blade of grass grows, and the forage grass fail to harvest. Rodent pests feed on forage grass and forage grass seeds, some of which store large amounts of forage grass in autumn and winter, which also reduces the carrying capacity and productivity of grassland. The frequent activities of rodents in grassland increase the exposed area of grassland, accelerate the evaporation of soil moisture, and reduce soil moisture content and soil fertility, thereby seriously affecting the sustainable development of grassland productivity. Second, rodents gnaw on grassland vegetation and grass roots, resulting in further degradation of grassland. Rodents gnaw and cut off the root system of plants, resulting in the death of a large number of above-ground plants, the reduction of many fine forage grasses, further degradation of grassland, and even desertification of grassland. Third, rodents spread plague, epidemic hemorrhagic fever, leptospirosis and other diseases, which will affect human health.

3 Prevention and control technology of grassland rodent damage

Chemical, physical, biological, ecological and comprehensive deratization methods are commonly used in grassland, among which chemical deratization and biological control are the most common methods.

3.1 Chemical control methodChemical control is the use of natural or synthetic chemicals to control rodent pests. Chemical control methods commonly used include poison bait control and fumigation control. Poison bait control method is the most commonly used control method, which is featured by low cost and high efficiency, and can control rodent damage in a short time, thus achieving the purpose of rodent control. Fumigation is generally applied to control underground rodents. It is the prevention and control method of applying fumigant to the hole and using poison gas to kill rodents. Commonly used rodenticides are divided into acute and chronic rodenticides. Acute rodenticides used in the past are highly toxic, and rodents will immediately die, but there is secondary poisoning dangerous to both human and animals, which will also pollute the grassland ecological environment.

3.2 Biological control methodBiological control method is a method to prevent and control rodent damage through the relationship between animals, plants or microorganisms and rodent pests. Biological control method includes microbial deratization and natural enemy deratization. Natural enemy control is to consciously use natural enemies such as foxes and eagles to capture and threaten rodents. At present, artificial eagle frames are installed on the grassland in Hami to control rodent damage, which has received remarkable effects, and the control area is constantly expanding.

3.2.1The effective way of grassland rodent control-attracting eagles to control rodents. In the past, chemical pesticide prevention and control method was mainly adopted, which not only killed rodents by using chemical pesticides extensively, but also killed the natural enemies of rodents, so that the natural ecological environment of grassland was damaged and polluted to varying degrees, and the ecological system was deteriorating. Since the release ofSeveralOpinionsonStrengtheningGrasslandProtectionandConstructionby The State Council, Hami City has gradually promoted the biological control technology of grassland rodents, and organized the rodent control work by biological pesticides such asClostridiumbotulinumC and D, which has achieved certain achievements. The control technology of attracting eagles to control rodents, which was applied in 2002, accounts for an increasing proportion year by year in grassland biological control against rodent pests, and the control area has been increasing. The control technology of attracting eagles to control rodents can effectively control the rodent damage in grassland.

There are many species and quantities of natural enemies against rodents, among which bird of prey (Falconiformes, Strigiformes) is a major group of natural enemies against rodents. An adult eagle can prey on 20-30 field rodents in a day, with a capture range of 300-500 m, and all rodents within this range can be captured in a few months. At present, the main birds of prey in Hami includeAquilaNipalensis,Aegypiusmonachus,Otusbrucei,Falkocherrug,etc.

3.2.2The popularization of artificial eagle frame in Hami City to attract eagles and control rodents. As early as 2002, Hami began to implement the "construction project of rodent-free demonstration area". Based on the prediction and forecast of rodent damage, the construction of rodent-free demonstration in grassland is a comprehensive control measure following the ecological concept of rodent control in grassland. The main technical route is centralized control of rodents by "biological pesticide+natural enemy control". The construction project of "rodent-free demonstration area" was set up in Dahe rodent damage area of Barkol County and Yanchi Township of Yiwu County, and "biotoxin (creotoxin C) control and biological control (set up eagle pier and eagle frame) were mainly adopted to prevent and control rodents. At that time, a total of 1 800 eagle frames were set up to control rodents by using eagle, a natural enemy of rodents. After the implementation of the "rodent-free demonstration area" project, the number of main rodent pests in grassland remained in the stage of "harmless rodents" for a long time. From 2019 to 2021, Hami City Locust and Rodent Pest Prediction and Control Station led the implementation of the project of attracting eagles to control rodents. A total of 2 000 eagle frames were installed on autumn and winter meadows in Barkol County, Yiwu County and Yizhou District. At present, 6 500 eagle frames have been established in Hami City, covering a rodent control area of 173 300 hm2, and the control effect is more than 90%.

3.2.3Distribution area of artificial eagle frames in grassland of Hami City. At present, eagle frames are mainly distributed in winter meadow in Haiziyan Township, Barkol County, winter meadow in Dahongliuxia Township, autumn meadow in Dahe Town, Barkol County, winter and autumn meadow in Yanchi Town, Yiwu County, winter and autumn meadow in Tuhulu Township, winter and autumn meadow in Xiamaya Township, white stone area in stud-farm of Yizhou District, Xiaobao winter meadow in Qincheng Township,etc.

3.2.4Standardize the technology of attracting eagles to control rodents and implement unified standards. Every district and county-level locust control station and grassland station in Hami City carry out the work of attracting eagles to control rodents every year according to the annual business work plan and combined with project work. Based on the accumulated experience and existing problems in the years of attracting eagles and controlling rodents, Hami City Locust and Rodent Pest Prediction and Control Station has implemented a unified standard for artificial eagle frames in the grassland of Hami City to further standardize the rodent control work by attracting eagles, which effectively plays the deratization effect of eagle frame. The distance between eagle frames is set according to the field of vision and movement law of eagle, the population of rodents and the terrain. The pier distance is generally 300-500 m, and an eagle frame could control 400 individuals of rodents. The unified standard of grassland eagle frame in Hami City is as follows. The eagle frame is C40 precast reinforced concrete column. The top cross arm is DN50 steel tube, perforated with Φ12 steel bar and linked with column; or Φ50 round wood, bound with Φ rebar. The frame is deeply buried at a depth of 0.6 m, and the foundation is done anticorrosion: asphaltic base oil once and emulsified asphalt twice. The bolts and L50×3 angle iron with the length of 0.3 m were embedded at the base. The font and size on the column shall be determined when preparing. For example, the font "Hami Zhaoyingmieshu 2020" shall be 0.6 m above the ground and painted; the weight of the frame is about 200 kg.

3.2.5Control effect on rodents. (i) Economic benefits. From 2002 to 2021, a total of 6 500 prefabricated eagle frames were installed in Hami City. Since the prevention and control area of each frame was roughly 26.67 hm2, the total prevention and control area was 173 300 hm2. According to the control cost of 45 yuan/hm2, deratization of eagle frame can save 7.8 million yuan for prevention and control. (ii) Ecological benefits. The implementation and promotion of biological control technology not only prevents rodent damage, but also protects the natural enemies of rodents, thus maintaining the grassland biodiversity and the virtuous cycle of the ecosystem. (iii) Social benefits. The intensity and frequency of rodent damage are lowered and the occurrence and spread of infectious rodent-borne diseases are reduced through the biological control technology of attracting eagles to control rodents. The chemical pesticide residues are decreased, which lays a foundation for the development of pollution-free grass and animal products.

4 Conclusions

Artificially attracting eagles to control rodents has good control effect, which is characterized by one-time investment, long-term use, low cost, no environmental pollution and long duration. It is an effective way to control rodent damage without destroying grassland ecosystem, which not only protect natural grassland and improve the vegetation covering ratio of grassland, but also receives remarkable social and economic benefits. In the future, the technology of attracting eagles to control rodents should be popularized.

In the future grassland rodent control work, the basic principle of prevention first, supplemented with comprehensive management should be insisted, so as to reduce the pollution of ecological environment. The biological control technology measures are adopted to control rodent damage, which can ensure the control effect while effectively restoring the grassland ecological environment.