Investigation and analysis of the damage of flower seedling scale insects and the analysis of control strategies
Liu Yanjun et al
Funds: Vocational Education Research Center of State Forestry Administration (LYZJ2018LX002), Shanxi Provincial Education Science "13th Five-Year Plan" Project (GH-18196), Shanxi Forestry Vocational and Technical College "Survey of Scale Insect Fauna in Taiyuan Fenhe Scenic Area" (20160202), Science and Technology Project of General Administration of Customs (2017IK164).
With the rapid development of the logistics industry, the transfer of flower seedlings is becoming more and more frequent, scale insects are easy to live in seedlings and flowers, invasive scale insects are small in form, strong adsorption, and often live in the shade of plants, it is easy to evade the quarantine inspection of plant quarantine officers, and spread into the country with the transfer of flower seedlings, which seriously threatens the safety of the local ecological environment.
In recent years, all localities have vigorously developed the garden industry, and a large number of flower seedlings have been introduced to decorate and beautify the park. With the planting of flower seedlings, the planting coverage rate of flower seedlings on both sides of the Fen River in Taiyuan City has increased, the plant species have increased, the management difficulty has increased, and the incidence of insect pests has increased year by year.
Scaleworms, commonly known as scale insects, belong to the family Coccoidea, small insects, difficult to identify, strong fecundity, large damage, mainly harmful to plant branches, leaves, etc., is one of the common pests in the garden, can cause devastating disasters in serious cases. Therefore, in view of the introduction of some mature flower seedlings in Taiyuan City, taking the Fenhe Scenic Area of Taiyuan City from 2016 to 2023 as the investigation base, a comprehensive investigation of the species and degree of scale insects in the Fenhe Scenic Area was carried out, and feasible comprehensive control measures were proposed.
1 Study design and data sources
1.1 Indicator selection
The Fenhe River Scenic Area was selected in Taiyuan City for investigation, located at 111°30'-113°09'E longitude and 37°27'-38°25'N latitude, including two parts: the wetland park and the pure artificial habitat of the Fenhe River Park, of which the wetland park is from the north side of the Cele Bridge in the north to the north side of the Shengli Bridge in the south, and the Fenhe Park is from the south side of the Shengli Bridge in the north to the north side of the Changfeng Bridge in the south.
1.2 Study Design
WPS office was used for data input and collation, SPSS22.0 was used for quantitative analysis, and SigmaPlot12.5 was used for plotting software.
1.2.1 Survey Methodology
Using the plant-by-plant survey method and the transect sampling survey method, two sample blocks (Shengli Bridge East to Changfeng Bridge East, Shengli Bridge West to Changfeng Bridge West) were selected in Fenhe Park, and two sample blocks (Shengli Bridge East to Celestial Bridge East, Shengli Bridge West to Celestial Bridge West) were selected in Wetland Park, and each sample plot was set up with a main transect to investigate the damage of trees, shrubs, grasses and flowers on each main line. There are also 5 quadrats between every 2 bridges on the east and west banks of the scenic spot, each quadrat is 10 m × 10 m.
The survey period was from 2016 to 2023, from May to September every year, and the survey was conducted continuously for 3 days from the 15th of each month, mainly to investigate the species and damage degree of scale insects in the quadrats. For trees with high branch points, the insect situation was judged by close inspection of the trunk and the color of the leaves from a distance (except for natural yellowing), and for trees with low branch points, the insect conditions were judged by close inspection of the branches, mosaic leaves and fruits. Sampling survey was carried out on trees with large planting density, especially the tree species with yellowing leaves out of season and weak tree vigor were the main survey objects, and the trees with low planting density were investigated one by one according to the transect. The shrub layer such as primrose rose, hibiscus, honeysuckle, lilac, etc., has a large planting density but a small planting area, a plant-by-plant survey with a small planting area, and a large planting area along the edge of the flowering area.
1.2.2 Definition of categories
The collected specimens were carefully removed from the host, stored in 95% ethanol, observed with a stereoscope Zeiss Stemi2000-CS (Germany), and identified and sorted with the help of Image-Pro Plus software. According to statistics, a total of 8 species of scale insects belonging to 8 genera and 5 families were found in the flower seedlings on the east bank of Fenhe Park, 12 genera and 12 species of scale insects in 5 families and genera were found in the flower seedlings on the west bank of Fenhe Park, 6 genera and 6 species of scale insects in 4 families, 6 genera and 6 species of scale insects were found in the flower seedlings on the east bank of the Wetland Park, and 8 species of scale insects in 5 families, 8 genera and 5 families were found in the flower seedlings on the west bank of the Wetland Park.
2 Results and Analysis
2.1 Species and degree of infestation
A total of 14 species in 14 genera and 5 families of scale insects were investigated, among which Mulberry shield scale, Korean hairball scale and sagittal scale were the dominant species.
2.2 Data analysis
According to the survey statistics, SPSS 22.0 was used for metrological analysis.
Statistical analysis of the number of scale insects at the survey site showed that through the statistical analysis of the number of scale insects parasitic on different trees in five lots, the number of scale insects in Shengli Bridge East to Changfeng Bridge East varied the widest range, reaching 204.66%, the minimum number of scale insects was 1, the maximum value was 1 880, and the average value was 364.50, and the average value of scale insects on different host trees in Yifenqiao West was the smallest, which was 25.89, the minimum value was 1, and the maximum value was 126. As can be seen from Table 2, there were no significant differences between or within groups. It can be seen from Figure 1 that the distribution of scaleworms from Shengli Bridge East to Changfeng Bridge East is the largest, the distribution of scale insects in Yifenqiao West is the least, and the distribution number of scale insects in the three sections from Shengli Bridge East to Cele Bridge East, Shengli Bridge West to Changfeng Bridge West and Shengli Bridge West to Cele Bridge West is in the middle state, and there is little difference between the three.
Table 1 Descriptive statistical analysis
Table 2 Analysis of variance
Figure 1 Map of the distribution of scaleworms in different locations
2.3 The cause of the occurrence of scale insects
2.3.1 The ecological environment is suitable
The ecological environment of high temperature and high humidity is one of the main reasons for the high survival rate of scales, due to the high humidity of Fenhe Wetland Park all year round, coupled with artificial irregular watering, it provides a good living environment for scales, and the east section of Shengli Bridge to Changfeng Bridge is the most obvious, mainly to shield scales and ball scale pests. According to the analysis, the beginning of the year is the budding growth period of the young shoots of the trees, and the shell of the bulblococcus insect pests can withstand the low temperature period at the beginning of the year, so at the time of the survey, the lunar scale pests in April and November were the main scale pest species of landscape trees. With the increase of temperature and humidity, the young shoots and young leaves of trees began to grow and mature, and shield scale and mealybug pests became the main pests of landscape trees on both sides of the Fen River, and the high temperature weather in Taiyuan City was generally from June to August, and the population density of scale insects also reached a peak, and the trees planted along the west coast of Shengli Bridge to the east of Changfeng Bridge were mostly landscape trees such as Acacia japonica, boxwood, and peach, and most of them were the main host plants of shield scales and coccidious pests, and 6-8 at the same time The month is also the main outbreak period of scale insect pests, so the species and number of scale insects in this section increased sharply, and the damage was the most serious.
2.3.2 Extensive garden management
After investigation, the daily management of each area of Fenhe Wetland Park is relatively extensive, the garden is not completely cleared in winter, the whitening is not in place, many planting areas rarely carry out deep land ploughing, and most of the watering adopts the method of flood irrigation or large-scale spraying, which will inevitably cause the breeding of scale insects and aggravate the degree of damage.
2.3.3 Weakening of phytosanitary conditions
In the process of quarantine inspection of exotic flower seedlings by the quarantine department, the scale insects are not easy to be found because of their small form. The scale damage is easy to be introduced into the garden with the flower seedlings, and the damage is aggravated. Most of the parks around Taiyuan City are planted with landscape trees such as acacia, boxwood, and peach, and in the breeding season of scale insects, shield scales and ball scales are aggravated by pests, which seriously affects the landscape effect.
2.3.4 Improper prevention and control measures
According to the survey and research, most of the direct managers of gardens in Taiyuan City have a low level of education, lack of knowledge about plant control, and blindly purchase drugs for prevention and control when pests and diseases occur, which often misses the best opportunity to kill insects. Scales are one of the most difficult insect pests to control, the surface of the insect body will form a wax, and eventually form a shell, the spray is not right, or it is difficult to touch the insecticidal body with ordinary agents, therefore, the best way to control scale insects is in the nymph stage.
3 Integrated prevention and control technology
3.1 Physical control
3.1.1 Whitening of the trunk
Choosing to whiten the trunk in the garden in winter can not only beautify the garden, avoid frost damage in early spring, but also effectively kill and prevent insects. The whitening agent is quicklime, salt, binder, stone sulfur mixture, and water in the ratio of 10:1:1:1:30.
3.1.2 Trunk barrier
In early spring, when most of the scales are in the incubation stage, a paper film is wrapped in a ring between the base of the trunk and 50 cm of the tree, which has a smooth surface to prevent the scales from crawling to the trunk.
3.2 Pharmaceutical prevention and control
Scale insects, also called scale insects, can secrete a kind of wax on the surface of the body to form a scale shell, which can effectively protect itself from external aggression, and it is difficult to make the agent enter the insect body when using drugs for prevention and control. Through investigation and research, it was found that the best control effect was in the incubation stage or young nymph stage of scaleworms, and insecticides such as 95% mineral oil 1 000~1 500 times, 22.4% spiroethyl ester suspension 4 000~5 000 times, 25% thiamethoxam suspension 4 000~5 000 times, 20% metformamidine emulsifiable concentrate 1 000~2 000 times or sodium pineate and other insecticides could be alternately controlled, and the best effect was best.
3.3 Biological control
Through investigation and research, it is found that the main scale insects on the trees in Fenhe Park of Taiyuan City are mulberry shield scale, Korean hairball scale, sagittal scale, etc., which can selectively release ladybugs, parasitic wasps, lacewings and other natural enemies, which should not only achieve the control effect of insect control, but also take effective measures to protect the beneficial insects. In the use of chemical pesticides for prevention and control, it is necessary to appropriately select agents that have little impact on natural enemies, so that natural enemies can maintain appropriate density in the garden, which can effectively control scale insects.
3.4 Seedling quarantine
Scales have the characteristics of small size, small range of activities, etc., parasitic on the plant is difficult to be found, therefore, when transporting foreign plants or grafting new plants, agriculture, forestry, customs quarantine departments should train professional identification personnel of scale insects, and must require professional quarantine personnel to carefully inspect in accordance with the plant quarantine inspection management measures to block the spread of scale insects from the source.
3.5 Landscaping management
3.5.1 Scientific Rational Cultivation
In the garden, we should choose more plants with strong resistance to stress and ornamental cultivation, and scientific and reasonable planning should be made when cultivating, such as classified cultivation, reasonable density, ventilation and light transmission, etc., which can not only improve the ornamentation of the garden, but also effectively reduce the incidence of plant diseases and pests.
3.5.2 Do a good job of maintenance on a regular basis
It is necessary to do a good job in the maintenance of garden plants on a regular basis, mainly including the following aspects.
1) Scientific fertilization. In spring and autumn every year, it is necessary to supplement the nutrients of plants in time, and use the method of hole application for arbor plants as much as possible, and the shrub plants should be fertilized by flooding or sprinkling with water, and when choosing fertilizers, organic fertilizers containing N, P and K elements or foliar fertilizers containing fulvic acids should be selected. 2) Scientific pruning. Choose to prune in winter or early spring, especially to cut off all the branches and leaves where the scale insects occur seriously, and the cut branches should be treated intensively to prevent the spread of pests, which can not only make the forest area ventilated and transparent, enhance the stress resistance of plants, but also effectively reduce the degree of scale insect damage.
4 Conclusion
The invasion and spread of scale insects has brought a serious threat to the ecology of the flower seedling industry, seriously restricted the ornamental nature of the garden park, and caused serious damage to the local ecological environment. Therefore, healthy flower seedlings should be transplanted, which is very important for the construction of ornamental garden parks and even the protection of the local ecological environment. After investigation and research, the prevention and control of scale pests should focus on the following aspects. 1) We must do a good job of quarantine. Intensify the quarantine of flower seedlings and transportation, and issue a transportation certificate only after the quarantine and disposal of infected plants is qualified. 2) Do a good job in the quarantine of the place of origin of flower seedlings, expand the area of plant sampling, increase the frequency of quarantine at the place of origin, strive to control the infected plants in the place of origin, ensure that the plants transported are healthy plants, and reduce the scope of the spread of scale insects. 3) After the flower seedlings are transported and planted, the monitoring of scale insects should be strengthened, and once serious scale damage occurs, chemical control should be carried out in time when the scale insects have not formed a scale shell to reduce the density of insect population. 4) Do a good job in garden management, clean up the dead branches and fallen leaves in time and burn them in a centralized manner, so as to reduce the overwintering base of scale insects.