Prevention and Control Test of Semiaphis heraclei in Spring

Lili JIAO, Suhui BAI, Yingxin ZHU, Xuekai SUN, Jun LIU, Xinyi HUO

1. Shijiazhuang Zoo, Shijiazhuang 050020, China; 2. Hebei Dongrun Landscape Technology Co., Ltd., Shijiazhuang 050061, China; 3. Hebei Academy of Forestry and Grassland Sciences, Shijiazhuang 050061, China; 4. Beijing Foreign Studies University, Beijing 100089, China

Abstract [Objectives] The paper was to study the prevention and control effect of botanical pesticides on Semiaphis heraclei at different temperatures. [Methods] When the daily average temperatures in spring were 15 and 20 ℃, the control effects of 0.3% azadirachtin EC 500 times dilution and 0.3% matrine AS 1 000 times dilution on S. heraclei were studied. [Results] When the daily average temperature was 15 ℃, 0.3% azadirachtin EC 500 times dilution had relatively good control effect on S. heraclei, with a long duration. The prevention and control of S. heraclei in spring better controlled the population quantity of S. heraclei fundatrix and reduced the degree of harm. [Conclusions] The study provides a basis for the pollution-free control of S. heraclei in the green space of parks.

Key words Lonicera maackii; Semiaphis heraclei; Botanical pesticide; Prevention and control forward

1 Introduction

Semiaphisheraclei, belonging to Aphididae, Hemiptera, is composed of wingless and wingless aphids. Wingless viviparous aphid 2.3 mm long and 1.3 mm wide, green or black-green, with thin white waxy powder on surface; epidermis rough, with rhomboid reticulate pattern; cornicle long cylinder, contracted at apex. Winged viviparous aphid: head and thorax black, abdomen green, anterior and posterior patches of cornicle healed, with independent marginal spots on the 1stto 6thabdominal segments, narrow transverse bands on the central dorsum of the 1stsegment, small medium lesions on the 5thsegment, transverse bands on the 6thto 8thsegments, and irregular transverse bands on the 6thsegment[1]. During leaf expansion ofLoniceramaackiiin spring,S.heracleicluster on the back of young leaves as nymphs and adults, causing abaxially curled and twisted leaves[2]. After flowering,S.heracleiadults cluster on the back of leaves or on the 1-2 a branches secreting wax powder to wrap the veins or shoots, resulting in sooty blotch of leaves. In severe cases, it causes early leaf declination, and even affects budding and flowering in the next year, which weakens the tree potential and affects the landscape effect ofL.maackii.S.heracleihas a wide range of hosts, and has the habit of alternate hosts. The first hosts includeL.japonica,L.chrysantha,L.maackii,etc.; the secondary hosts include celery, fennel, Chinese parsley, carrot and other Umbelliferaceae plants[3]. The aphids that hatch out of overwintering eggs are called fundatrix, which are wingless. Wingless females (fundatrix) are reproduced by parthenogenesis in summer. It has been reported that the 1stto 4thinstar larvae have developed when the daily average temperature reaches 15 ℃[4-5]. In Shijiazhuang area, when the daily average temperature in spring reaches 13 ℃,S.heracleihas started parthenogenetic reproduction, and caused damage at the early leaf expansion stage ofL.maackii. When the daily average temperature is 20 ℃, the harms caused byS.heracleireach the peak in late April and early May, which gradually decrease in late May, andS.heracleigradually migrates to secondary hosts in early June[6]. In late September and early October,S.heracleiflies back to the first hostL.maackii, and spawns to survive the winter. Live overwinteringS.heracleiadults have not been found in spring.

The prevention and control of plant diseases and insect pests in urban green space should be based on prevention, and supplemented with chemical control. Environment-friendly drugs should be applied as far as possible to reduce the impact of chemical drugs on the ecological environment around green space.S.heracleiin green space of Shijiazhuang City was controlled by botanical pesticide, and the effect of temperature on control effect was studied, in order to provide a scientific basis for the pollution-free control ofS.heracleiin the green space of parks.

2 Materials and methods

2.1 MaterialsL.maackiiin Shijiazhuang Zoo were selected as the research object. The botanical pesticides used in the test were 0.3% Azadirachtin EC (Chengdu Green Gold Biotechnology Co., Ltd.) and 0.3% matrine AS (Hebei Fuji Biotechnology Co., Ltd.). Electric sprayer, face mask, goggles, gloves, labels,etc., were also used in the test.

2.2 MethodsEighteen 5 m×5 m plots were selected from the green space planted withL.maackiiin Shijiazhuang Zoo and randomly divided into 2 groups, with 9 plots in each group. The plots sprayed with 0.3% Azadirachtin EC 500 times dilution and 0.3% matrine AS 1 000 times dilution were designed as treatments A and B, and those sprayed with clean water were regarded as treatment C (control). Each treatment had 3 replicates, and each replicate had 2 clumps ofL.maackiiplants. All treatments were in random block arrangement. Three branches of each plant were randomly selected fromL.maackiiplants in 5 directions: east, south, west, north and middle. The total number of live nymphs and adults ofS.heracleiwere investigated before administration and at 7 d post administration, and the corresponding survey results were recorded. The dropping rate of insects was calculated: Dropping rate of insects (%)=(Number of live insects before administration-Number of live insects after administration)/Number of live insects before administration ×100%. Control effect (%)=(Dropping rate of insects in treatment area-Dropping rate of insects in control area) (100-Dropping rate of insects in control area)×100%.

From 2017 to 2019, when the daily average temperature in spring reached 15 ℃ for consecutive 5 d, a pre-drug survey was conducted in the first group of plots. It was clear and windy on the day of the test. 0.3% Azadirachtin EC 500 times dilution and 0.3% matrine AS 1 000 times dilution were sprayed evenly on the back of tender buds and leaves in the evening until there were uniform drops staying on leaves. Personal protection should be well done when spraying. In order to avoid interaction between chemicals, 2 electric sprayers were prepared. The experimental plants were sprayed once every 10 d for 3 times. When the daily average temperature reached 20 ℃ for consecutive 5 d,L.maackiiplants in the second group were sprayed following the same operation in the first group.

3 Results and analysis

The control effects of different daily average temperatures and botanical pesticides onS.heracleiare shown in Tables 1-2. As the initial population quantities were similar before administration of botanical pesticides, 0.3% Azadirachtin EC 500 times dilution led to a large dropping rate of insects, and received good control effects, with long duration. When the daily average temperature was 20 ℃, the population quantity was up to 1 000 individual/plant, which was nearly 3 times of that at 15 ℃. When the daily average temperature exceeded 15 ℃, the development duration ofS.heracleigenerations was shortened, and the reproduction rate was accelerated, resulting in frequent damage. Therefore, when the population quantity was small, administration of botanical pesticides had little impact on flowering landscape ofL.maackii.

The daily average temperature of 15 ℃ in spring is the temperature at whichS.heracleistarts to develop[5]. When the fundatrix ofS.heracleiare reproduced in large quantities, the spread should be controlled in time. In this study, botanical pesticides were used to controlS.heracleiat developmental threshold temperature in spring, which reduced the population quantity of fundatrix while reducing the impact of chemical agents on the surrounding environment. In addition, botanical pesticides suitable for parks were selected in accordance with phenological temperature for the prevention and control ofS.heraclei, and relatively good results were achieved (Tables 1-2).

Table 1 Control effects of botanical pesticides on Semiaphis heraclei at the daily average temperature of 15 ℃

Table 2 Control effects of botanical pesticides on Semiaphis heraclei at the daily average temperature of 20 ℃

In the 3-year control test, it was found that when the temperature began to rise to 15 ℃ in spring, the prevention and control ofS.heracleiat this moment had better effect than that conducted when a large number of aphids occurred. After continuous 3-year control,L.maackiiplots were slightly damaged byS.heraclei, and they were less attacked by other diseases and insect pests than that without prevention and control forward. Two botanical pesticides can be used together for year-round pollution-free control ofS.heraclei.

In urban green spaces, it is suggested that the control ofS.heracleiin spring should be advanced to the initial development stage of the 1stto 4thinstar nymphs, that is, when the daily average temperature reaches 15 ℃ for consecutive 5 d, which will not only reduce the population quantity of fundatrix but also lower the incidence of diseases and insects throughout the year. Meantime, the use of botanical pesticides for pollution-free prevention and control can not only reduce the damage to the green landscape caused by large-scale occurrence ofS.heraclei, but also reduce the impact of chemical agents on the urban green environment.