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杨毒蛾(Stilphotia candida Staudinger )又称为杨雪毒蛾,属于鳞翅目(Lepidoptera)毒蛾科(Lymantriidae)[1],主要危害杨树(Populus L.)、柳树(Salix L.)、白桦(Betula platyphylla)、榛子(Corylus heterophylla)等植物[2-3]。杨毒蛾幼虫期以杨柳树的叶片为食,暴发性极强,大规模发生时,数天之内即可将树上的叶片食光,严重削弱树势甚至造成树木的死亡,此外杨毒蛾还常常引发杨树溃疡病和腐烂病并发症[4-6],因此对树木危害极大。根据揭路兰等[7]人的研究表明,杨毒蛾在我国及日本等国均有分布。近年来,杨毒蛾在拉萨和林芝频繁发生,连续数年循环发生危害,严重影响杨柳树的生长发育和当地生态安全[8-14]。国外目前仅见Keisuke Ueda等[15-16]人对其生物学特性做过研究,国内华北、华东等受杨毒蛾危害较为严重的地区目前仅对杨毒蛾的形态特征、发生规律、防治方法等方面开展了相应的研究[17-21];然而上述研究一方面距今已有较长时间,另一方面绝大部分研究重点集中在杨毒蛾的防治措施而缺乏对杨毒蛾生物学特性进行详细的阐述,且昆虫在不同生境下其生物学特性不同[22],西藏地区由于其特殊的生境杨毒蛾的生物学特性发生了哪些变化目前还尚不明确,因此本实验从昆虫与寄主挥发物之间的化学通讯角度切入,一方面观察杨毒蛾在西藏地区生物学特性发生的变化,另一方面探究寄主挥发物在其生活史中所发挥的作用,其次由于连年的化学农药使用3R效应愈发明显,因此明确其生物学特性,对后续无公害防治工作的开展提供理论依据。
于2021年4月到2022年7月以西藏自治区林芝市巴宜区结麦村为定点定期观测基地,同时采集杨毒蛾各虫态在实验室进行饲养观察,对该害虫的年生活史、生活习性和各发育阶段形态进行系统性研究,为该地区科学防治杨毒蛾及后续深入研究打下理论基础。
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虫卵为球形,直径0.97±0.02 mm,初产时为灰褐色,产后1—2 d颜色逐渐加深为黑褐色;一雌蛾可连续产卵1—3 d,产下2—3个卵块,解剖未产卵雌虫测得平均卵量为197±28.823 粒;雌虫产卵时分泌白色液体与卵一并产出后覆盖在卵表面,随后凝固将卵粒包裹(见图1a~b)。
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杨毒蛾幼虫为5龄,其各龄幼虫特征值见表1;老熟幼虫头部浅棕褐色,有光泽,有2个大小形状相同的黑斑对称分布于头部两侧,幼虫头部两侧有5对侧单眼排成弧形,身体为黑褐色每节上着生5对黑色肉瘤,气门线上方靠近背部中线处1个肉瘤着生针状刚毛,气门线下方4个肉瘤分为两对,每对的两个肉瘤上下紧挨着,上方肉瘤着生的刚毛较短,下方肉瘤着生的根毛较长;背中线为黑色两侧为黄棕色,冠缝两侧各有黑色纵纹一条,气门线为灰褐色,气门棕色,腹部棕色,足为白色,其中胸足3对,腹足5对,腹足和臀足趾钩单序缺环式(见图1c~i)。
1龄 1st instar larva 2龄 2nd instar larva 3龄 3nd instar larva 4龄 4th instar larva 5龄 5th instar larva 头宽/mm head width (mm) 0.58±0.03 1.34±0.04 2.30±0.04 3.23±0.05 4.31±0.07 体长/mm body length (mm) 2.53±0.07 6.49±0.34 11.09±0.41 20.86±0.45 30.47±0.41 Table 1. Characteristic value of each insect age of Stilphotia candida Staudinger
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蛹长15.84±0.85 mm、宽6.04±0.33 mm、质量0.23±0.04 g,雄虫蛹长13.73±0.61 mm、宽5.14±0.26 mm、质量0.14±0.02 g(见表2);杨毒蛾蛹为被蛹,棕褐色有光泽,每体节保留着幼虫期毛瘤的特征,其上密生黄褐色长毛;蛹尾部有22.6±3.07(n=10,5♀,5♂)根臂棘,成集束状,外面有包鞘(见图1j~n)。
蛹数量
Pupa number蛹体长/mm
Pupa body length (mm)蛹体宽/mm
Pupa body width (mm)蛹质量/g
Pupa quality (g)30(♀) 15.84±0.85 6.04±0.33 0.23±0.04 30(♂) 13.73±0.61 5.14±0.26 0.14±0.02 Table 2. Measured characteristic value of Stilphotia candida Staudinger pupae
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杨毒蛾成虫前后翅均为白色,翅面上有白色鳞片且有光泽,翅上有白色鳞片时是不透明的,将白色鳞片抹去则翅是透明的。雄虫翅展37.92±1.73 mm,体长15.28±1.10 mm,触角长8.02±0.38 mm,触角为黑色,羽状;雌虫翅展48.13±1.57 mm,体长19.82±1.46 mm,触角长9.31±0.45 mm(见表3),基部粗,端部细,为黑色,丝状;成虫下唇须黑色,足为黑色,胫节和跗节有白环。腹部为暗棕色,表面长有白色绒毛。雄虫复眼一般大于雌虫。杨毒蛾成虫翅的连锁方式为翅缰连锁;前翅由1条亚前缘脉、5条径脉、3条中脉、2条肘脉和1条臀脉组成,其中Rs与M1共柄,R3脉端部开叉,M1与M2间有一条横脉,M2与M3接近;后翅由2条径脉、3条中脉、2条肘脉和2条臀脉组成,其中Sc和R1合并,M1与M2间有横脉。(见图1o~q)
数量
Number特征值 Characteristic value 名称
Organ name最长/mm
Longest (mm)最短/mm
Shortest (mm)平均值/mm
Average value (mm)标准差/mm
Standard deviation (mm)30 (雄) 体长 body length 16.70 13.82 15.28 1.095 翅展 wing expanse 41.72 35.66 37.92 1.732 触角 antenna 9.13 7.11 8.02 0.376 30 (雌) 体长 body length 22.67 18.70 19.82 1.463 翅展 wing expanse 51.72 44.54 48.13 1.571 触角 antenna 10.16 8.02 9.31 0.451 Table 3. Characteristic value of adult Stilphotia candida Staudinger
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杨毒蛾雌虫常将卵产于杨柳树叶背面。卵初产时为灰褐色,产后1—2 d颜色逐渐加深为黑褐色,近孵化时卵壳透明,幼虫形态特征清晰可见。杨毒蛾虫卵发育受温湿度的影响,自然环境中观察到的卵期较人工气候箱中显著更长(见表4),说明较为稳定的温湿度条件可以加快杨毒蛾卵的发育速度,两种条件下卵的孵化率均在95%以上。
发育阶段
Development stage发育历期
Development duration条件一
Condition 1条件二
Condition 2卵 egg 19.63±1.54a 20.17±2.34b 幼虫 larva 39.53±2.65a 44.03±4.00b 蛹期 pupa 9.63±1.61a 9.67±1.81a 注:1、同行中相同小写字母表示差异不显著(P>0.05,t测验),反之差异显著(P≤0.05)。条件一:自然环境中(温度:17℃~25℃,RH为45%~55%)条件二: 人工气候箱中(温度:10 h—20℃、14h—25℃;RH:60%~70%;光照周期:L:D=14 h:10 h)
Note: The same lowercase letters in the same row indicate no significant difference (P>0.05, T test), but the difference is significant (P≤0.05). Condition 1: In natural environment (temperature: 17℃~25℃, RH is 45%~55%) Condition 2: In artificial climate box (temperature: 10 h-20℃, 14 h-25℃; RH:60%~70%; Illumination period: L:D=14 h:10 h)Table 4. Development duration of Stilphotia candida Staudinger at different stages
在饲养过程中发现,杨毒蛾卵孵化需要寄主挥发物刺激;通过控制变量法,控制两组虫卵的发育条件一致;进行试验后发现,寄主挥发物对虫卵的发育并无显著影响,即使没有寄主挥发物的刺激,卵也可正常发育,且透过卵壳清晰可见发育完成的幼虫虫体,但幼虫不能正常孵出,若此时加入杨树小枝幼虫及可孵出,否则虫卵将不断干瘪直至死亡。
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杨毒蛾卵多在凌晨集中孵化,幼虫孵化时用上颚将卵壳顶部咬破,随后蚕食一部分卵壳后爬出,此过程持续5—10分钟,杨毒蛾初孵幼虫就具有较强活动能力,孵化后便可开始取食,当食物极度匮乏时幼虫会以卵壳为食,通过蚕食卵壳幼虫可发育至2龄并存活相当长的时间,未发现幼虫以未孵化卵为食;杨毒蛾1—3龄幼虫喜群居生活,4龄后常3—5头聚集。温湿度通过影响幼虫的取食量进而影响幼虫的发育历期,在人工气候箱较为稳定的温湿度条件下杨毒蛾幼虫的发育历期显著短于自然条件下(见表4),当温度低于15℃时幼虫取食量与活动量开始减少;杨毒蛾幼虫具有避光性,且避光性随虫龄递增,1—3龄幼虫白天多聚集在叶柄处,4龄后幼虫开始下树,白天在树皮缝内侧隐藏自己夜间上树取食,而在人工饲养条件下因没有树皮缝躲避幼虫常常吐丝拉网隐蔽自己;蜕皮前幼虫也会吐丝将自己包裹,待蜕皮后从顶部将丝咬开爬出。1—3龄幼虫好食新展叶片的叶肉,4龄幼虫取食量大幅增加开始沿叶缘吞食整个叶片,5龄幼虫至化蛹前期食量开始逐渐减少;杨毒蛾幼虫共5龄,各虫龄发育历期均为5—7 d。
在林芝地区发现杨毒蛾主要对杨柳树造成危害,对杨毒蛾幼虫进行不同食物区分饲养后发现,在同时饲喂北京杨和白柳树叶片的条件下杨毒蛾幼虫更为倾向于取食北京杨,在北京杨叶片取食殆尽后才会开始取食白柳;结果发现取食两种不同食物的杨毒蛾幼虫在发育历期和存活率方面存在显著差异,北京杨饲喂下的幼虫在发育历期更短,且幼虫成活率显著高于白柳叶片饲喂(见表5)。
不同食物
Different kinds of food数量(只\每盒)
Number per box幼虫发育历期(天)
Larval development period(d)幼虫每盒平均存活数
Larvae survive several北京杨 Populus × beijingensis W. Y. Hsu 30 44.03±4.00a 14.9±4.13a 白柳 Salix alba L. 30 45.57±4.62b 12.1±5.64b 注:1、同行中相同小写字母表示差异不显著(P>0.05,t测验),反之差异显著(P≤0.05)。
Note: The same lowercase letters in the same row indicate no significant difference (P>0.05, T test), but the difference is significant (P≤0.05).Table 5. Effects of different kinds of food on the development duration and survival rate of Stilphotia candida Staudinger
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杨毒蛾蛹为被蛹,老熟幼虫吐丝将自己固定在树皮缝内侧化蛹。蛹初期为淡褐色随后颜色逐渐加深,即将羽化的蛹为深褐色。羽化时,腹部摆动,成虫从顶部将蛹壳顶裂后钻出,成虫破蛹钻出后一般0.5—1 h展翅完全,在展翅完成后成虫才会开始活动。通过对比,两种条件下蛹期均为9 d左右(见表4)差异性不显著;野外,5月下旬末杨毒蛾开始在树皮缝里化蛹,统计6月上旬野外采集的239头蛹,测出杨毒蛾蛹的羽化率为96%。
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杨毒蛾成虫多在夜间活动,白天多静匿于叶片背面或地表灌木中。蛹羽化多集中在每日20:00 到次日凌晨1:00,尤以夜间23:00 为羽化高峰期,成虫羽化后3—5 h便可开始交尾,交尾时雌雄虫腹部末端先试探性接触,随后雌虫用翅将雄虫盖住。交尾多集中在凌晨4:00—7:00,交尾持续11—17 h,据观察最长一次交尾时间长达25 h(在实验室无干扰的环境下);除非受到外界刺激否则雌雄成虫交尾期间少有活动,雄蛾有二次交尾现象,雌蛾只交尾1 次,若雌蛾羽化72小时后仍无雄虫前来交尾,多数雌虫也会将卵产下,其卵为青色且不能正常孵化。雌蛾平均寿命4.9±0.94 d,雄蛾平均寿命5.7±0.84 d表6。
性别
Gender虫数
Worm number最长存活历期
Maximum survival duration最短存活历期
Minimum survival duration平均存活周期
Average survival duration雌虫 female 30 6.5 4 4.9±0.94 雄虫 male 30 7 5 5.7±0.84 Table 6. Survival duration of male and female adults of Stilphotia candida Staudinger
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通过野外定期观察记录,杨毒蛾在西藏林芝地区一年发生一代(见表7)。以2—3龄幼虫在杨柳树皮缝内侧或地表枯枝落叶层中越冬;翌年4月中下旬待杨柳树展新叶时开始活动,进入5月随着日积温逐渐增加幼虫的活多时间也随着延长,多数幼虫发育至4—5龄采食量大幅增加开始为化蛹做准备,6月上旬幼虫陆续进入树皮缝内侧化蛹,至7月下旬老熟幼虫全部化蛹;蛹经过9.67±1.81 d羽化为成虫,成虫于6月中旬开始羽化,6月下旬达到羽化高峰期;杨毒蛾成虫白天多静匿于叶片背面或地表灌木中夜间活动交尾,在6月中旬至8月上旬均可见成虫活动交尾;待交尾结束后即可开始产卵,雌虫产卵喜选择树势强健的杨柳树,多将虫卵产于叶背面;7月中旬幼虫开始出现,8月下旬因温度和日照时间的减少幼虫取食量活动量随之减少,随着气温越来越低幼虫开始下树,于9月上旬陆续开始越冬。
1-4月
January-April5月
May6月
June7月
July8月
August9-12月
September-DecemberE M L E M L E M L E M L E M L E M L ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◇ ◇ ◇ ◇ ◇ ◇ ○ ○ ○ ○ ○ ○ ◫ ◫ ◫ ◫ ◫ ◫ ◫ ◫ 注:E、M、L分别代表每个月的上旬、中旬、下旬;○代表卵、◒代表幼虫、◇代表成虫、◫代表蛹。
Note: E, M and L represent the early, middle and late days of each month respectively; ○ represent the egg, ◒ represent the larva, ◇ represent the adult, ◫ represent the pupaTable 7. Annual life history of Stilphotia candida Staudinger
Study on Biological Characteristics of Stilphotia candida, in Nyingchi, Tibet
doi: 10.12172/202211070002
- Received Date: 2022-11-07
- Available Online: 2023-04-06
- Publish Date: 2023-10-25
Abstract: Stilphotia candida Staudinger, as an invasive species introduced into Tibet in recent years, harms the growth of local willow trees. The biological characteristics of the insect pests were systematically studied, which laid a theoretical foundation for the prevention and control of Stilphotia candida Staudinger in this area and the further research. Through the methods of field investigation, regular observation and indoor breeding, from April 2021 to July 2022, a fixed field observation base was set up in Jiemai village, Nyingchi city, and samples were collected for indoor rearing. The morphological characteristics, living habits and annual life history of Stilphotia candida Staudinger in Nyingchi, Tibet were systematically studied. The results showed that Stilphotia candida Staudinger occurred once a year in nyingchi Tibet, and began to overwinter with 2-3 instar larvae in mid-September. The overwintering sites were mainly inside the bark seams of willow branches or in the ground litter layer, and the overwintering larvae began to harm the newly developed leaves of poplar and willow in the middle and late April of the following year. During the feeding process, it was found that host volatiles were one of the necessary conditions for the normal hatching of Stilphotia candida Staudinger eggs, and the eggs could develop normally without the stimulation of host volatiles, but the larvae could not be hatched. Through the separate feeding of willow leaves, it was found that the larval stage of Beijing poplar leaves was significantly shorter than that of white willow leaves, and the survival rate of larvae was higher. Most of the Stilphotia candida Staudinger adults emerged at night and mate in the early morning of the next day, and the mating time was as long as 11-17 hours. At natural temperature conditions, the measured egg stage, larval stage and pupal stage, male/female adult period were 20.17±2.34 d, 44.03±4.00 d, 9.67±1.81 d and 5.7 ±0.84 /4.9±0.94 d, respectively.