新疆同域亚洲玉米螟和欧洲玉米螟发生与分布研究

Sympatric occurrence and distribution of Asian corn borer and European corn borer in Xinjiang

中国新疆伊犁是当前世界范围内唯一一处已知的亚洲玉米螟和欧洲玉米螟同域混生区。本文通过调查这一混生区玉米螟的野外主要寄主种类及其玉米螟群体组成和混生杂交情况,为后续开展同域近缘种种间竞争、群体进化和杂交等研究提供本底数据。在田间寄主系统调查的基础上利用mtCOⅠ基因测序和OR 4基因酶切法对混生区内4个主要县市5种寄主上的986个疑似玉米螟样本进行鉴定分析。结果表明:新疆伊犁混生区内玉米螟的野外寄主主要是玉米、高粱、稗草、狗尾草和苘麻,偶见苍耳、大麻、反枝苋等。942个样本被鉴定为亚洲玉米螟,相似性为99.02%~100%;44个样本被鉴定为欧洲玉米螟,相似性为99.24%~100%。亚洲玉米螟在混生区内所有调查地内均有分布,且比欧洲玉米螟具有更广泛的寄主范围,其主要取食并分布在玉米、高粱、稗草、狗尾草和苘麻上,混生比例依次为73.33%~100%、100%、88.89%~100%、95.00%~100%、100%。欧洲玉米螟分布则极为有限,目前仅主要分布在紧邻中亚哈萨克斯坦的霍尔果斯市和伊犁河谷最东部、西天山腹地新源县的极少数区域,所占比例较低,且主要取食玉米,偶见取食稗草、狗尾草,在3种寄主上的混生比例依次为0~26.67%、0~11.11%、0~5.00%。所有样本未发现杂合个体,均为纯合体。综上,亚洲玉米螟目前已在混生区内所有主要寄主植物上均成功取代欧洲玉米螟,成为混生区绝对优势种。

The Ili area of Xinjiang Uygur Autonomous Region in China represents the only known region where Ostrinia furnacalis has invaded the range of native O.nubilalis.By determining their sympatric hosts,population structure and distribution,this study aimed to provide the basic data for further research of their interspecies competition,population evolution and hybridization.Based on the field host investigation,986 suspected corn borer samples from five hosts in four counties of Ili region were identified by microsatellite cytochrome C oxidase subunitⅠgene(mtCOⅠ)sequencing and odorant receptor 4(OR 4)gene digestion.The results showed that the wild hosts of corn borer in this mixed area were mainly Zea mays,Sorghum bicolor,Echinochloa crus-galli,Setaria viridis,Abutilon theophrasti,and occasionally Xanthium strumarium,Cannabis sativa and Amaranthus retroflexus.A total of 942 samples were identified as Asian corn borer(ACB),with a similarity of 99.02%-100%;forty-four samples were identified as European corn borer(ECB),with a similarity of 99.24%-100%.The ACB populations were widely distributed in all investigated areas and had a wider host range than ECB,mainly feeding Z.mays(73.33%-100%),S.bicolor(100%),E.crus-galli(88.89%-100%),S.viridis(95.00%-100%)and A.theophrasti(100%).By contrast,ECB populations had an extremely limited distribution range,and they were merely distributed in a few areas of Khorgos city(sharing a border with Kazakhstan)and Xinyuan county(in the easternmost part of the Ili River Valley and the hinterland of West Tianshan Mountain).ECB populations were mainly distributed on Z.mays and occasionally on E.crus-galli and S.viridis,with a proportion of occurrence on these three host plants of 0-26.67%,0-11.11%and 0-5.00%,respectively.All of the samples were homozygous.Taken together,ACB populations,with a wide distribution in all investigated areas,have successfully replaced ECB populations on all major host plants,and ACB has become the dominant species in the Ili region of Xinjiang.