Technical Specifications for Integrated Prevention and Control of Yellow Aphids

Jie HAO, Jinxin WANG, Jingmiao HUANG, Xueying LI, Xinmin YAN, Jianzhong FENG, Xiangmin SUO

Shijiazhuang Pomology Institute, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050061, China

Abstract [Objectives] The purpose was to standardize the scientific prevention and control of yellow aphids and effectively control their occurrence and spread. [Methods] On the basis of consulting domestic and foreign data and standards extensively, a series of related trials were carried out. [Results] Technical specifications for integrated prevention and control of yellow aphids were formulated. [Conclusions] It is of great significance to the healthy and sustainable development of the fruit trees’ industry, the implementation of standardized management, the reduction of pesticide uses, and the reduction of damage caused by yellow aphids to fruit trees, and also provides urgent-needed technical support and guarantee for the prevention and control of yellow aphids.

Key words Yellow aphids, Integrated prevention and control, Technical specification

1 Introduction

Apple is an important fruit in China, with large planting area and high output, ranking among the best in the world. It has become one of the pillar industries of China’s rural economy, and plays an important role in advancing the adjustment of agricultural structure, increasing farmers’ income and promoting foreign exchange earnings through exports.

Yellow aphids (

Aphis

citricola

van der Goot) (Hemiptera: Aphididae) are a serious leaf pest to fruit trees. They mainly damage apple, hawthorn, orange, pear, plum, apricot, crab apple, birch-leaf pear, papaya, loquat, mandshurica, and so on. In the main apple production areas of China, they are one of the leaf pests with the largest population, the widest range and the longest occurrence. Yellow aphid occurs more than 10 generations a year in northern China. The eggs overwinter in the slits of the thick bark and buds of apple branches, and will hatch with the germination of apple trees. From May to June, the occurrence of wingless aphids is generally serious; after late June, a large number of winged aphids spread in apple orchards; from July to August, yellow aphids may appear in some apple saplings and apple nurseries; there may be also a few in early September; and from October to November, sexual aphids appear, followed by mating, egg laying and overwintering. Yellow aphids tend to damage the young shoots of fruit trees and live by sucking juice from fruit trees. The feeding amount of aphids of different species and ages varies greatly. The minimum food intake per hour was 1% of body weight, and the maximum was 133%. The sucking of juice is very harmful to plants, and it can make the leaves bend downward or roll horizontally, affecting the photosynthesis of leaves and the normal growth of branches. When yellow aphids occur seriously and damage apple trees continuously, a lot of water and nutrients lose every day. The damage of yellow aphids will lead to the lack of nutrients and the deterioration of nutritional status in plants, leading to delayed or stagnated growth of roots, stems, leaves and flowers, making plant tissues age in advance. When the occurrence is serious, the tree vigor will be weakened and the fruit yield will be affected eventually. In addition, yellow aphids will affect the quality of fruits. Their excreta is transparent viscous liquid and tastes sweet, so it is called honeydew. When the density of yellow aphids is high and their food intake is large, the honeydew will be increased, covering the plant surface like oil, affecting the respiration and photosynthesis of plants. If the climate is suitable, a mold layer will form on the honeydew, becoming "sooty mold", causing plant malnutrition, leading to plant growth obstacles.

In recent years, yellow aphids have been common in apple tree cultivation areas of China. In particular, sapling nurseries and mature apple trees in full fruiting stage are seriously damaged, causing great losses to apple production. When the population density of yellow aphids is high, they will damage the fruits. Because of their rapid propagation speed, if it is not paid more attention to, the difficulty of prevention and control will be increased, causing immeasurable economic losses. Yellow aphids are a typical pest of R strategy, with short generational cycle and fast reproductive rate. They can be parthenogenetic or hermaphroditic. In summer, it is parthenogenesis, which makes the quantity of yellow aphids increase geometrically. Yellow aphids are classified into winged aphids and wingless aphids, which often occur in a mixture. After the end of June, a large number of winged aphids are produced and transferred to other hosts, which brings great difficulties to integrated prevention and control. Yellow aphids tend to threaten young shoots, and they will occur with the growth of fruit branches. Due to the obvious increase of apple cultivation area in China in recent years, the number of overwintering eggs of yellow aphids is increasing. At present, in production practice, the control of yellow aphids is dominated by chemical control and artificial control. However, the widespread use of highly toxic and residual pesticides makes the control effect not ideal. They not only pollute the environment and harm the health of pesticide applicators, and moreover, they are prone to causing potential impact on fruit quality and destroying the stability of orchard ecological community. In short, it is difficult to control yellow aphids in production. Usually, even repeated pesticide applications every year is far from achieving effective control. The majority of fruit farmers often feel helpless. Therefore, in the prevention and control of yellow aphids, the corresponding technical specifications and standardized management are urgently needed to reduce the damage.

The relevant international standards have not yet been retrieved. The results of standard search show that there are no relevant national standards, industry standards and current provincial and local standards for the integrated control technology of yellow aphids.

Referring to relevant national and industrial standards, according to the occurrence regularities of yellow aphids in Hebei Province, on the basis of investigation, analysis and experimental research, specific requirements were put forward for the investigation of the pest incidence, the division of the damage degree, the prevention and control indices, the prevention and control methods, and the investigation of the prevention and control effect of yellow aphids, and integrated prevention and control technical specifications for yellow aphids were formulated, helpful to standardize the scientific prevention and control of yellow aphids, improve the control effect and effectively control the propagation and spread of the pest. This plays an important guiding role for scientific control of yellow aphids, healthy growth of trees, improvement of apple yield and quality, and vigorous development of apple industry, and can significantly reduce the economic losses of fruit farmers and promote the healthy development of ecological benefits.

The integrated prevention and control technology of yellow aphids is an important technical requirement for the development of apple industry. Formulating technical specifications for integrated prevention and control of yellow aphids in apple is of great significance for the healthy and sustainable development of apple industry, the implementation of standardized management, the reduction of pesticide use and the reduction of the damage caused by yellow aphids.

2 Materials and methods

Technical

Specifications

for

Integrated

Prevention

and

Control

of

Apple

Yellow

Aphids

is the task of "formulating local standards" issued by Hebei Provincial Bureau of Quality and Technical Supervision in 2018. Shijiazhuang Pomology Institute, Hebei Academy of Agriculture and Forestry Sciences was responsible for drafting the standard. On August 19, 2020, the specifications passed the provincial achievement appraisal and reached the leading level in China. The provincial registration number is 20201179, and the standard release number is DB 13/T 5168-2020.

2.1 Materials

The materials used mainly included yellow aphids collected from apple trees, trap band, yellow sticky plate (Beijing Zhongjie Sifang Biotechnology Co., Ltd.), lime sulfur, thiamethoxam, imidacloprid, beta cypermethrin, flonicamid, spirotetramat, matrine, and toosendanin (Hebei Weiyuan Biochemical Co., Ltd.).

2.2 Trial time and site

The trial was conducted in the Shijiazhuang Comprehensive Test Station of National Apple Industry Technology System,

i

.

e

., the Shijiazhuang Pomology Institute of Hebei Academy of Agriculture and Forestry Sciences (38°27′ N, 114°30′ E) from February, 2017 to September, 2019.

2.3 Methods

2.3.1

Information consultation. National, industrial and local standards, including

Guidelines

for

Safety

Application

of

Pesticides

(GB 8321.1-GB 8321.6),

General

Guidelines

for

Pesticide

Safe

Use

(NY/T 1276-2007),

Technical

Specifications

for

Integrated

Prevention

and

Control

of

Apple

Woolly

Aphid

(DB13/T 1734-2013),

Technical

Specifications

for

Integrated

Prevention

and

Control

of

Apple

Mite

(DB13/T 1277-2010) and

Technical

Specifications

for

Forecast

of

Yellow

Aphid

(DB37/T 1295-2009), were consulted. At the same time, more than 40 relevant data and standard literatures were extensively collected and deeply studied to understand the research status and progress.

2.3.2

Trial conduction. In view of the main problems existing in the integrated prevention and control of yellow aphids, focusing on investigation of incidence, division of damage degree, prevention and control indices, prevention and control methods and investigation of prevention and control effect, based on in-depth investigation and many years of experiments, the problems in the prevention and control of yellow aphids were understood, the incidence of yellow aphids in multiple cities and counties of Hebei Province was investigated, and advanced experience in prevention and control of yellow aphids was summarized.

2.3.3

Procedure development. The technical indices for each link of integrated prevention and control of yellow aphids, including incidence investigation, economic threshold, prevention and control method, and prevention and control effect investigation, were defined and standardized.

3 Results and analysis

3.1 Incidence investigation

3.1.1

Investigation time. During April-September, the incidence of yellow aphids in apple trees was investigated once every 7-10 d.

Yellow aphids in Hebei Province have 15-18 generations a year and overwinter in the form of fertilized egg in twig axils, branches and crevices. In late March of the next year, the overwintering eggs begin to hatch when the apple trees are budding. In late April, viviparous winged or wingless aphids appear sporadically. With the increase of air temperature, the spring shoots of apple trees grow vigorously, and the population of yellow aphids increases slowly, reaching about 5% on May 4, and then begins to increase sharply, reaching the peak of 37.2% on June 10. During this period, the occurrence peak of yellow aphids is positively correlated with the growth of new shoots, and this period is the time when yellow aphids occur most seriously, and is also the key period of prevention and control in a year. During this period, the number of yellow aphids increases sharply, often accompanied by a large number of winged aphids that appear and migrate. In the middle and last ten days of June, with the coming of rainy season, the number of rainfall days and precipitation increase significantly, and the quantity of yellow aphids begins to decrease obviously. After August 9, the incidence of yellow aphids is kept below 10% (Fig.1). Affected by weather, temperature or climate, the peak incidence of yellow aphids is different in different years. The high incidence period of apple yellow aphids is from the middle of May to the middle of June, the season with high temperature and less rainfall.

Fig.1 Dynamics of incidence of yellow aphids in apple trees during 2017-2019

3.1.2

Investigation method. Aphids infection rate of shoots was investigated according to the local situation with ocular estimation method.

Five fixed apple trees were selected from the orchard, and five young shoots were randomly selected from the eastern, southern, western and northern parts of each tree. Thus, 20 young shoots were selected from each tree, and total 100 shoots were investigated.

3.2 Determination of economic threshold

Aphids infection rate of shoots was investigated with ocular estimation method. When the economic threshold of aphids infection rate exceeds 30% in young trees, or exceeds 45% in adult trees, comprehensive chemical control measures should be taken immediately. The results are shown in Table 1 and Table 2.

As shown in Table 1, when the aphids infection rate was more than 31%, the damage of yellow aphids to young apple trees was serious, causing an irreversible effect on the growth potential. Therefore, the economic threshold of young trees is that aphids infection rate reaches 30%. If it is above the economic threshold, it is necessary to take chemical measures immediately to perform prevention and control for young trees.

It can be seen from Table 2 that when the aphids infection rate was more than 46%, the damage of yellow aphids to adult apple trees was severe, causing an irreversible effect on the growth potential. Therefore, the economic threshold of adult trees is that the aphids infection rate reaches 45%. If the economic threshold is exceeded, it is necessary to take chemical methods immediately to control yellow aphids in adult trees.

3.3 Prevention and control

3.3.1

Agricultural prevention and control. In early spring, the trunk and main branches are barked carefully before the eggs hatch to remove the overwintering eggs in the thick bark, branches, buds and crevices in time. During pruning, the number of main branches and their direction and position on the trunk are adjusted according to the tree shape. The over dense branches and spindling branches should be removed in time to ensure the ventilation and light transmission among rows, inter-plants and inner-plants. Combined with summer pruning, the aphid infected branches are cut off and taken out of orchard for centralized destruction or deep burying, which is time-saving, labor-saving and environmental friendly, with remarkable effect. The application of organic fertilizer is increased properly to enhance the pest resistance.

(i) Trap band. In the first ten days of October, the trunk of each apple tree is tied with a trap band. In February of the next year, the trap bands will be taken off and burned centralizedly to kill the eggs of overwintering aphids and various pests and reduce the base population of pests in the coming year. Tying up trap bands has a good trapping and killing effect on overwintering eggs, reducing the number of hibernating in the next year. It can reduce the frequency of drug use in the next year and reduce pesticide residue pollution.

From 2017 to 2019, trap bands were tied to the trunk of each apple tree in the orchard, 80-100 cm above the ground. In the spring of the next year, the trap bands were removed and burned, and the base quantity of yellow aphids in the thick bark, branches, buds and crevices was investigated. As shown in Table 3, tying trap bands could significantly reduce the number of overwintering eggs and the number of hibernating in the next year.

Table 3 Effect of trap band treatment on base quantity of yellow aphids in apple trees

(ii) Yellow sticky plate. In the process of migration, winged aphid has obvious yellow tendency. By utilizing this kind of yellow tendency of yellow aphids, yellow sticky plates are developed to kill winged aphids effectively. In middle May, the plates, 25 cm×20 cm, are hanged outside the main branches of the middle and upper parts of apple trees, 150-300 plates per hectare. In the first ten days of June when a large number of yellow aphids migrate, yellow sticky plates have a good trapping and killing effect. In the first 20 d, the average number of aphids trapped per plate per day was 400. After the 20th d, the stickiness of the yellow plates is affected by wind, sun and dust. If the number of winged aphids is still large, the yellow plate should be replaced or glued in time. Yellow sticky plates can obviously inhibit the increase of quantity of yellow aphids.

Plastic yellow sticky plates (25 cm×20 cm, Beijing Zhongjie Sifang Biotechnology Co., Ltd.) were used in the trial. They were applied with sticky glue on both the sides. In the peak incidence of yellow aphids in apple (from the middle of May to the middle of June, the trial time was June 10, 2017-2019) trees, the yellow sticky plates were hanged on the outside of the main branches of the middle and upper part of apple trees, 20 plates per 0.067 ha.

Yellow sticky plates showed a significant effect on trapping and killing winged aphids. Table 4 shows that on the 5, 10and 20d, 1 545.6, 3 650.3 and 7 515.5 winged aphids were trapped in each yellow plate on average. The results also show that within the 20 d, the natural enemies that yellow plates attracted were lacewing and hoverfly larvae. The average number of natural enemies trapped by each yellow plate was 1.8, and the killing effect was obvious. The ratio of yellow aphid to natural enemies was 4 175∶1. This not only protects the ecological environment, ensures the existence of natural enemies, but also promotes the safe production of fruit trees.

Table 4 Average quantity of winged aphids stuck on per yellow sticky plate

3.3.2

Biological prevention and control. The predatory natural enemies of yellow aphids include lacewings, hoverflies,

Coccinella

septempunctata

,

Propylaea

japonica

Thunbery,

Harmonia

axyridis

, and the parasitic natural enemies are

Aphytis

spp.,

Asaphes

vulgaris

Walker and Orius spp. These natural enemies play an important role in controlling the occurrence of apple yellow aphids. As long as they do not cause economic harm, the use of chemical agents should be reduced, and instead, the natural enemies should be fully utilized. Warm winter, temperature rise in early spring, rainy weather, vigorous growth of apple branches and shoots and large leaf evaporation are all conducive to the occurrence of natural enemies. In chemical control, chemicals with little or no effect on natural enemies should be selected. What’s more, they should be spayed when the activity of natural enemies is small.

3.3.3

Chemical prevention and control. We should strengthen the forecast of yellow aphids, make timely use of pesticides, select safe and efficient pesticides when necessary, strictly implement GB 8321 (all parts), use pesticides with different action mechanisms alternatively, and combine the use of pesticides reasonably, to delay the resistance of yellow aphids and improve the control effect.

During the growth period, based on the investigation results of aphids infection rate in the whole orchard, when the chemical control index is reached, chemical prevention and control should be conducted timely.

During the dormancy period, lime sulfur, diesel oil emulsion and engine oil emulsion are sprayed to fruit trees to effectively eradicate overwintering eggs of apple yellow aphids. At the very beginning of budding and full hatching of eggs, thiamethoxam should be sprayed as soon as possible to eliminate the young aphids. After the hatching of overwintering eggs, imidacloprid, beta cypermethrin and other wettable powder or

EC

are sprayed in time, in order to reduce the base population of aphids in spring and control the early damage. Pesticides should be applied in strict accordance with the use concentration, evenly and comprehensively. The spraying force should be larger, so that the liquid medicine can directly touch the pest body. At the same time, attention should be paid to alternate use of different types and dosages of insecticides, to delay the emergence of resistance.

The control efficacy of flonicamid (3 000-fold diluted), spirotetramat (4 000-fold diluted), imidacloprid (2 000-fold diluted) all reached 100% after sprayed for 3 d, with high efficiency and quick acting (Table 5). Among them, the control effect of flonicamid was the best. Its mechanism is novel, and it has fast antifeedant activity and good neurotoxicity to pests with piercing-sucking mouthparts, such as yellow aphids. The control efficacy of matrine (1 000-fold diluted) and toosendanin (1 000-fold diluted) was more than 65% after sprayed for 7 d, relatively poor. However, as extracted from plants, non-toxic and no residue, they are the most promising pesticides for high-quality organic apple production in the future, and can replace the conventional imidacloprid and other pesticides.

Table 5 Control efficacy of several pesticides on yellow aphids in apple trees

3.4 Investigation of prevention and control effect

3.4.1

Calculation of prevention and control effect. From the 2d of the spraying of pesticides, the aphids infection rate was investigated once every 2 d to analyze the control efficacy.

3.4.2

Evaluation of prevention and control effect. If the aphids infection rate was below the economic threshold 3-7 d after the pesticide application, it was considered qualified. Otherwise, supplementary prevention and control was conducted.

4 Discussion

There have been no relevant national standards, industry standards and provincial and local standards for the integrated prevention and control technology of apple yellow aphids, except for

Technical

Specifications

for

Integrated

Prevention

and

Control

of

Apple

Woolly

Aphid

(DB13/T 1734-2013),

Technical

Specifications

for

Integrated

Prevention

and

Control

of

Apple

Mite

(DB13/T 1277-2010),

Technical

Specifications

for

Forecast

of

Apple

Yellow

Aphid

(DB37/T 1295-2009). The relevant technical parameters for the integrated prevention and control of yellow aphids are not clear. There is no mature experience for reference in the formulation of this standard. Therefore, extensive investigation and a large number of in-depth research was conducted in this study, relevant technical indices were demonstrated, modified and verified repeatedly, and eventually, advanced, systematic and practical technical specifications were formed in 2020. The formulation of this standard can provide technical support and guarantee for the prevention and control of yellow aphids in apple.