Species and Occurrence of Scarab in Sweet Potato Growing Areas of Xuzhou，Jiangsu

Hui YAN，Cheng XUE，Yungang ZHANG，Daifu MA，Qiang Ll*

1.Sweet Potato Research Center in Xuzhou，Jiangsu/Key Laboratory of Biology and Genetic Breeding of Sweet Potato in Ministry of Agriculture/Institute of Sweet Potato in Chinese Academy of Agricultural Sciences，Xuzhou 221131，China

2.Xuzhou Biological Engineering Professional Technology Institute，Xuzhou 221007，China

Species and Occurrence of Scarab in Sweet Potato Growing Areas of Xuzhou，Jiangsu

Hui YAN1，Cheng XUE2，Yungang ZHANG1，Daifu MA1，Qiang Ll1*

1.Sweet Potato Research Center in Xuzhou，Jiangsu/Key Laboratory of Biology and Genetic Breeding of Sweet Potato in Ministry of Agriculture/Institute of Sweet Potato in Chinese Academy of Agricultural Sciences，Xuzhou 221131，China

2.Xuzhou Biological Engineering Professional Technology Institute，Xuzhou 221007，China

Frequency-vibrancy pest-killing lamp was used to calculate the numbers and types of scarabs during the growing period of sweet potato in Xuzhou area，thus to study the occurrence regularity of scarab and effect of meteorological factor on its occurrence，which provided a reference and guidance for the control of grub in sweet potato field.The monitoring results indicated that scarabs in sweet potato planting area of Xuzhou mainly included Anomala corpulenta，Holotrichia parallela Motschulsky，Maladera verticalis and Holotrichia trichophora Fairm.Holotrichia trichophora Fairm has entered into its late stage at the early cultivation stage of sweet potato with a few occurrence quantities.The elongation stage of sweet potato vine is the full incidence period of imagoes of Maladera verticalis and Anomala corpulenta.Full incidence period of Holotrichia parallela Motschulsky is from late June to middle August，the outbreak cycle of which is long.The unearthed imagoes follow the regular change"many-few-many-few".Effects of meteorological factor on the activities of various scarabs are different.The activities of various scarabs are frequentin warm and windlesssunnydays.In rainy days，Holotrichia parallela Motschulsky，Holotrichia trichophora Fairm and Maladera verticalis are inactive.The numbers of Anomala corpulenta in cloudy days but not rainy days are higher than that in sunny days.

Sweet potato；Scarab；Occurrence regularity；Meteorological factor

T here are many types of scarabs in Xuzhou area，which seriously affects peanut，sweet potato and wheat.Imagoes of scarab gnaw crop leaves and can lead the leaves to death.Larvae，grubs mainly damage crop roots and affect the absorption of nutrients and water，and even lead whole plant to death［1］.Sweet potato is an important economic and energy crop in China.Grub is an important insect pest that affects the quantity and quality of sweet potato.Growing period of northern summer sweet potato is from early June to late Octorber，which is the full incidence period of imagoes of Anomala corpulenta and Holotrichia parallela Motschulsky［2］.Studying the occurrence regularity of scarab in the growing period of sweet potato can not only effectively control imagoes of scarab and decrease the population quantity，but also predict the occurrence tendency of scarab in the nest year，thus to provide a reference for sweet potato production and control of grub.

Materials and Methods

Survey site

The investigation site is the sweet potato field in Sweet Potato Research Center of Xuzhou，Jiangsu.Sweet potatoes have been continuously planted in the field for eight years and scarabs have not been controlled during the planting period that the grub damage is very serious.The south of the potato field is peanut field and the north of the potato field is rice field，and the west and east of which are main roads.

Table 1 Morphological characteristics of four types of scarabs

Survey tools

Frequency-vibrancy pest-killing lamp；type:GY-15A；working voltage: 220 V；wavelength of lamp of frequency vibration:320-680 nm.

Survey method

Taking the advantage of scarab’s preference forwave，frequency-vibrancy pest-killing lamps were used to trap and survey scarabs during the growing period of sweet potato.The trapping area is 1.67 hm2and two frequency-vibrancy pest-killing lamps were used that the average trapping area is 0.83 hm2/lamp.The trapping period is from the transplanting（June 10，2013）to the harvest（October 9，2013）of sweet potato，which count up to 120 d.Weather situation was accorded every day and trapped scarabs were collected and classified at 08:00.

Data analysis

Microsoft excel 2003 was used to process data and make graph for statistical analysis of the survey results.

Results and Analysis

Types and occurrence regularity of scarabs in sweet potato field in Xuzhou area

According to the 120 d investigation during the growing period of sweet potato，four kinds of scarabs were found to be the main species that largely affected the sweet potatoes in Xuzhou area （Table 1）.A total of 10 844 scarabs were trapped.The quantities and occurrence regularities of the scarabs were very different（Fig.1）.

According to the light trapped number，middle June was found to be the full incidence period of Anomala corpulenta. Holotrichia parallela Motschulsky and Maladera verticalis were the most active from middle July to late July，especially Holotrichia parallela Motschulsky，which reached the full incidence period of imago during thatperiod，and the average trapped number reached 154 head/d. Moreover，the damage cycle was the longest and the scarabs disappeared basically in early September. Holotrichia trichophora Fairm came to its late stage in middle June and disappeared basically in late July，which was accorded with the investigation results of Li et al［2］.

Occurrence quantities of scarabs at differentgrowth stage ofsweet potato

Elongation stage of sweet potato vine is within the 60 d after transplanting and growing period of potato tuber is the 60-90 d after transplanting.During the 120 d （from transplanting to harvest）investigation，the occurrence quantities of various scarabs were found to be different.The trapping number of Holotrichia parallela Motschulsky was the largest with a percentage of 47.74%.The number of Anomala corpulenta ranked only second to thatofHolotrichia parallela Motschulsky and the percentage of which was 24.21%.The third largest was the number of Maladera verticalis. The percentage ofHolotrichia trichophora Fairm was only 7.98% ，which was the fewest（Table 2）.The monitoring results showed that 9 556 scarabs were trapped within 50 d after the transplanting of sweet potatoes and the number was the largest with a percentage of 88.1%.In the first 10 d，Anomala corpulenta was the main trapping pest and had 49%of the total trapped number in the ten days，and Holotrichia trichophora Fairm ranked only second to Anomala corpulenta with a percentage of 20%.During the 21-40 d after transplanting，the trapped scarabs were mainly Holotrichia parallela Motschulsky and Maladera verticalis.From the 51 d after transplanting to harvest，the trapping number of scarabs was fewer and Holotrichia parallela Motschulsky was the main types.

Effect of meteorological factor on the occurrence of scarab

Trapping numbers ofdifferent scarabs in the full incidence period were investigated and weather conditions were recorded every day for 20 d.The average occurrence numbers of different scarabs under different meteorological factors were accounted. The monitoring results showed that different meteorological factors had different effects on the occurrence of scarabs.Trapping numbers of scarabs showed obvious differences with the changing of meteorological factors.Inwarm and windless sunny days，activity of each scarab was frequent. Holotrichia parallela Motschulsky had 42.81%of the whole trapping number in sunny days，which was the largest. In rainy days，occurrence quantities of the three kinds of scarabs were fewer than thatin sunny days except Anomala corpulenta.Cloudy and rainy weather slightly affected the activity of Anomala corpulenta and the trapping numbers of Anomala corpulenta in cloudy days and rainy days were 90.22%and 88.99%of the total numbers，respectively.The average occurrence number of Anomala corpulenta in cloudy days reached 125，which was higher than that in sunny days illustrating that Anomala corpulenta prefer to activate in cloudy days（Table 3）.

Table 2 Occurrence quantity and percentage of each scarab at different growth stage of sweet potato

Table 3 Correlations between average daily occurrence number of scarab and meteorological factor

Survey on unearthed regularity of Holotrichia parallela Motschulsky

The statistical results showed that the unearthed number of imago of Holotrichia parallela Motschulsky in clear night followed the regular change of “many-few-many-few” （Fig.2）. From 19 July till 22 July，the weathers were sunny that the trapping numbers of Holotrichia parallela Motschulsky were 121，26，340 and 183，respectively.However，such phenomenon did not occur in other three scarabs.From 27 July to 30 July，the weathers were rainy that Holotrichia parallela Motschulsky was nearly inactive，and unearthed imagoes in the early and late occurrence stage of Holotrichia parallela Motschulsky showed the same tendency.

Discussion

The main host plant of scarab is soybean［3］and the effect of scarab on sweet potato yield is not obvious.However，its larva，grub is the main injurious insect that affects the yield and quality of sweet potato.Many methods for the control of grub have been reported，such as natural enemy control and microbial control［4-7］.Currently，chemical control with hole application is still the main method.For chemical control，chemical agents are easily combined with organic matters in soil and kept in potato tubers and environmentthatresulted in food safety problems.Moreover，chemical control can lead to high resistance of injurious insect.Therefore，in order to protect environment and food safety，it is necessary to make the best use of the growth characteristics of injurious insects to find safer and more efficient comprehensive treatment methods for the control of insects.The trapping number of injurious insects by frequency-vibrancy pest-killing lamp was 2-5 times of that by general black light lamp.The control area of each frequency-vibrancy pest-killing lamp was 2-3 hm2and spectrum of trapped insects was wide that 1 000 kinds of injurious insects including scarab，cotton bollworm and european corn borer could be trapped［8］.It is an important tool for the physical control of injurious insects.

Scarabs have chemotaxis，vergence and preference for wave［9，10］. Using moth-killing lamp，leavening substance and sex attractant to trap scarabs，thus to decrease the imago number，limit the population quantity in a certain level and decrease grub number is economical，practical，easy to be operate and safe.It is the transplanting date to elongation stage of sweet potato vine within 60 d after transplanting，which is a key period for the growth of sweet potato.During the period，imagos of Anomala corpulenta，Holotrichia parallela Motschulsky and Maladera verticalis largely occur and frequently activate that imago control should be emphasized in this stage. The activities of most scarabs were largely affected by meteorological factors.In warm and windless sunny days，scarabs activated frequently. However，in cloudy and rainy days，unearthed numbers of the three kinds of scarabs were fewer except Anomala corpulenta.Therefore，weather condition should be monitored during the control of scarabs and it is better to choose sunny and windless night for trapping.

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Responsible editor：Yingchun YANG

Responsible proofreader：Xiaoyan WU

江苏徐州甘薯种植区金龟子种类调查及发生趋势初探

闫 会1，薛 程2，张允刚1，马代夫1，李 强1*
（1．中国农业科学院甘薯研究所/农业部甘薯生物学与遗传育种重点实验室/江苏徐州甘薯研究中心，江苏徐州 221131；2．徐州生物工程职业技术学院，江苏徐州 221007）

利用频振式杀虫灯对徐州地区甘薯生长期金龟子发生种类和数量进行统计分析，研究金龟子发生规律及气象因子对其发生活动的影响，为甘薯田蛴螬的防治提供借鉴及指导。监测结果表明，徐州甘薯种植区金龟子主要有铜绿丽金龟、暗黑鳃金龟、阔胫红绒金龟、毛黄褐金龟4种。毛黄褐金龟在甘薯栽插初期已进入发生末期，发生量少；薯蔓并长期正值阔胫红绒金龟、铜绿丽金龟成虫盛发，诱捕数量多；暗黑鳃金龟盛发期为6月下旬至8月中旬，发生周期长，且成虫出土表现出“多—少—多—少”的规律性变化。气象因子对各种金龟子的活动影响差异较大，温暖无风的晴天各种金龟子均活动频繁；阴雨天暗黑鳃金龟、毛黄褐金龟、阔胫红绒金龟3种金龟子基本不活动；铜绿丽金龟阴天成虫诱捕数量甚至高于晴天，雨天则活动较少。

甘薯；金龟子；发生规律；气象因子

国家“863”计划（编号：2012AA101-204）；现代农业产业技术体系建设专项（编号：CARS-11）；江苏省科技支撑计划 （编号：BE2012336、BE2013437）。

闫 会（1988-），女，山东聊城人，硕士，从事甘薯育种研究，E-mail：yan．hui19881218@163．com。*通讯作者，博士，研究员，主要从事甘薯育种研究，E-mail：instrong@163．com。

2015-09-03

Supported by National 863 Program （2012AA101204））；Project for the Construction of Modern Agricultural Industry Technology System （CARS-11）；Science and Technology Support Program in Jiangsu（BE2012336 and BE2013437）.

*Corresponding author.E-mail:instrong@163.com

Received:September 3，2015 Accepted:November 10，2015

修回日期 2015-11-10