枣园桃蛀果蛾寄生蜂种类及其与寄主的关系

Investigation of populations of parasitic wasps parasitizing Carposina sasakii Matsumura(Lepidoptera: Carposinidae) in jujube orchards in China, with respect to the wasp-host relationship

桃蛀果蛾(Carposina sasakii Matsumura)是我国十分重要的果实性害虫,其中枣受害最严重,因其幼虫在果实内蛀食危害、高度隐蔽性的生活而较难防治。寻找有效天敌,开展生物防治成为必然。2009年与2010年研究调查了我国大枣部分产区陕西、山西、河南与宁夏枣园桃蛀果蛾寄生性天敌,共发现了3种寄生蜂,即中华齿腿姬蜂(Pristomerus chinensis Ashmead)、章氏小甲腹茧蜂(Chelonus(Microchelonus)zhangi Zhang)和金小蜂(Pteromalidae),3种寄生蜂均从桃蛀果蛾的茧中羽化而出,其中中华齿腿姬蜂和章氏小甲腹茧蜂为优势天敌,但它们表现出十分明显的地域性分布。同时,对中华齿腿姬蜂和章氏小甲腹茧蜂羽化、寄生率以及与寄主之间的关系进行了初步研究,结果表明,中华齿腿姬蜂越冬代成虫出蛰活动始于6月中旬,越冬代寄生率较低,第1代成虫羽化在8月下旬至9月上旬,这代寄生蜂具有较高的寄生率,可达25%;章氏小甲腹茧蜂第1代成虫羽化集中在8月中下旬和9月上旬,由于在2009年与2010年对样地进行不施用杀虫剂的管理,该天敌在2010年自然寄生率显著提高,最高时可达64.52%。因此,科学管理,合理保护与利用当地天敌成为实现该害虫生物防治的关键。

The peach fruit borer Carposina sasakii Matsumura（Lepidoptera： Carposinidae）（= Carposina niponensis（Walsingham）） is a harmful and widespread pest insect that attacks many types of fruit,including apple,peach and jujube,in northern China.Among these hosts,jujube has been most severely affected,with about 90% of Chinese jujube orchards being damaged.The larvae drill into the fruit and eat the pulp and kernel,producing bore dust and frass that make the fruits inedible by humans,and causing the fruit to fall from the trees.The quality and quantity of fruits affected by the borer are markedly reduced,as are the yields of infested orchards,causing large economic losses.The peach fruit borer is predominantly found in Asian countries（China,Japan,Korea） and the far east of Russia.Because of the risk to fruit orchards,in 1988 the European and Mediterranean Plant Protection Organization placed C.sasakii on the A1 list of pests recommended for control by quarantine.However,the peach fruit borer is difficult to control because it is concealed within the fruit,and general methods of pest treatment fail to achieve sustainable control.It has therefore become necessary to identify and utilize natural enemies of this pest to develop a bio-control strategy.Many researchers have worked on this problem,and have obtained valuable data and results.However,there are many factors that remain to be elucidated;for example,precisely which species are parasitoids of the peach fruit borers that attack the jujube tree,how are they restricted to their host,and what is the host-parasitoid relationship？ In this project,we investigated populations of parasitic wasps attacking C.sasakii in jujube orchards in Shaanxi,Shanxi and Henan provinces and in Ningxia Hui Autonomous Region in 2009—2010.Three species of parasitic wasp were identified（Pristomerus chinensis Ashmead,Chelonus（Microchelonus） zhangi Zhang and a species of Pteromalidae） and all were reared from their host cocoons.P.chinensis Ashmead and C.（M.） zhangi Zhang are both preponderant agents,but their population size varied markedly among the above four regions;P.chinensis was found predominantly in Shaanxi and Shanxi provinces,whereas C.（M.） zhangi was observed principally in Henan.The relationship between emergence,parasitism rate and host were studied for P.chinensis and C.（M.） zhangi.The results indicate that P.chinensis emerged half a month later than its host.Adult hosts emerged from over-winter cocoons in the middle of June,with a parasitism rate of 8.86%;the summer generation emerged from the last week of August to the first week of September,with a 25% parasitism rate.For C.（M.） zhangi,the summer generation emerged from the middle of August to the first week of September.In general,fruit drop occurred in the first（in 2010） to the second（in 2009） week of August in jujube orchards in Puyang city,Henan province;C.（M.） zhangi began to emerge one week later,with the peak emergence at 10—12 days.The graph of parasitism rate for C.（M.） zhangi revealed three time periods： from 16 to 26 August,from 27 to 31 August and from 1 to 8 September.As a whole,the parasitism rate declined from the first period to the third,which could be related to host behavior.No insecticide was used in the experimental areas during the years 2009—2010;as a consequence,the parasitism rate for C.（M.） zhangi increased markedly to 64.52% in 2010.Thus,it can be seen that local natural enemies have been playing an important role in controlling the peach fruit borer naturally,and should be protected and utilized appropriately.