寄生和捕食元宝枫种子瘿蚊的重要天敌——毛链金小蜂属一新种(膜翅目:金小蜂科)

A Parasitic and Predatory Natural Enemy of Acumyia sp.that Eats Seeds of Acer truncatum:A New Species of Systasis(Hymenoptera:Pteromalidae)

【目的】元宝枫是我国珍贵经济林树种,其籽油中含有丰富的神经酸等物质,在预防和治疗人类神经系统疾病上具有重要价值。然而,近年来作者发现元宝枫种子受到一种元宝枫瘿蚊(Acumyia sp.)幼虫的严重侵害。为了无公害防治该害虫,本研究旨在调查并鉴定元宝枫瘿蚊的天敌。【方法】通过在北京和内蒙古的实地调查,发现了寄生和捕食元宝枫瘿蚊幼虫和蛹的一种小蜂。通过分类研究,确定其为小蜂总科金小蜂科毛链金小蜂属Systasis的一个新种——元宝枫瘿蚊毛链金小蜂Systasis aceri Yang,Liu et Cao sp.nov.。本文详细描述了该寄生蜂的形态特征,并附有彩色形态特征图。同时,还记述了该小蜂的生物学,也和毛链金小蜂属我国的二个相近种进行了比较,提供了鉴别特征。【结果】该新种与中国的一种寄生刺槐叶瘿蚊的小蜂——叶瘿蚊毛链金小蜂Systasis obolodiplosis Yao et Yang相似,但可以通过以下特征进行区分:新种体呈金绿色,雌性体长3.4~3.6 mm,雄性1.8~2.4 mm(而后者体呈蓝色,带有紫色金属光泽;雌性体长2.1 mm,雄性1.3 mm);唇基略呈方形,宽为高的1.4倍(后者的唇基更宽,宽度是其高度的2.0倍);腹部较长,长为宽的2.7倍(后者的腹部较短,长为宽的1.8倍)。Xiao&Huang修订了中国毛链金小蜂属的种类,并提供了9个种的分类检索表。使用此检索表,新种最初被归为Systasis procerula Xiao et Huang。然而,本新种雌性在其他特征上存在差异:痣后脉长度是痣脉的1.4倍(后者的痣后脉短于痣脉);触角较短,梗节加鞭节的长度是头宽的1.15倍(后者是头宽的1.4倍);本种腹部更长,长为宽的2.7倍(后者腹部较短,长为宽的1.5倍)。此外,还描述了新种的生物学特性。元宝枫瘿蚊毛链金小蜂对元宝枫瘿蚊幼虫和蛹具有较高的寄生率,达到34%。其1~2龄幼虫为寄生性,而3龄以后则转为捕食性,能将单个种子中的52~125头瘿蚊幼虫(或蛹)捕食殆尽。该小蜂一年发生2~3代,是元宝枫瘿蚊的主要天敌。【结论】本天敌的发现为无公害生物防治元宝枫瘿蚊提供了一种优秀天敌。这一发现对于保护元宝枫这一珍贵树种及其籽油资源具有重要意义,并为未来种实害虫提供了新的生物防治技术。

【Objective】Acer truncatum is a precious economic forest tree species in China,and its seed oil contains rich nervonic acid and other substances,which is vital for preventing and treating human neurological diseases.However,in recent years,we have found that A.truncatum seeds have been severely damaged by the larvae of a Cecidomyiid species,Acumyia sp.(Diptera).The present study aims to investigate and identify the natural enemies of Acumyia sp.for environmentally friendly pest management.【Method】Through field investigations in Beijing and Inner Mongolia,as well as indoor rearing,a chalcid wasp that parasitizes and preys on the larvae and pupae of Acumyia sp.was discovered.A taxonomic study was subsequently conducted,revealing the parasitoid as a new species,Systasis aceri Yang,Liu et Cao sp.nov.,which belongs to the genus Systasis(Hymenoptra,Chalcidoidea,Pteromalidae).In this paper,the new species is described in detail,and color photos are provided.Additionally,the biology of this wasp is reported and compared with other related species.【Result】This new species is similar to a parasitic wasp in China,Systasis obolodiplosis Yao et Yang,also a Cecidomyiid parasitoid,but can be distinguished by the following characters:the new species has a golden-green body color,with female body length of 3.4-3.6 mm and male body length of 1.8-2.4 mm(whereas the latter has a blue body with a purple metallic tint;female body length of 2.1 mm and male body length of 1.3 mm);the clypeus shape is square-like with width 1.4 times its height(the latter’s clypeus is much wider,with a width 2.0 times its height);the gaster is long,with a length 2.7 times of its own width(the latter’s gaster is shorter,with a length only 1.8 times its width).Xiao&Huang revised the species of the genus Systasis in China and provided a key to nine species.Using this key,the new species was initially misidentified as Systasis procerula Xiao et Huang.However,the female of the new species differs in other characteristics:post-marginal vein length is 1.4 times the stigmal vein(the latter’s post-marginal vein is shorter than the stigmal vein);antenna is shorter,with the length of pedicel plus flagellum being 1.15 times the head width(the latter is 1.4 times the head width);gaster is much longer,with a length 2.7 times its own width(the latter’sgaster is shorter,with a length only 1.5 times its width).Additionally,the biology of the new species is discussed.The parasitism rate of the new species on the larvae and pupae of Acumyia sp.was about 36%.Its 1st-2nd instar(when they were young and smaller)larvae were parasitic,while the 3rd instar(when they grew larger)and later larvalstages became predatory,capable of preying on 35-52 Acumyia sp.larvae(or puparium)within a single seed.Usually there were 60-126 individuals of the cecidomyiid larvae fed in a single seed and 4-6 parasitoid larvae parasitized/preyed.However,only 1-3 wasps finally emerged.The wasp occurs 2 generations per year and is a preliminary natural enemy of Acumyia sp.【Conclusion】The discovery of this natural enemy provides an excellent biological control agent for the Acer seed pest Acumyia sp.This finding is important for protecting the precious tree species A.truncatum and its seed oil resources,offering a potential technique for future biological control of the seed pest.