de León Jesse H, Jones Walker A
United States Department of Agriculture, Agricultural Research Service, Subtropical Agricultural Research Center, Beneficial Insects Research Unit, 2413 E. Highway 83, Weslaco, Texas 78596, USA.
J Insect Sci. 2005;5:2. doi: 10.1093/jis/5.1.2.
The aim of genetically comparing different populations of the same species of natural enemies is to identify the strain that is most adapted to the environment where it will be released. In the present study, Inter-Simple Sequence Repeat-Polymerase Chain Reaction (ISSR-PCR) was utilized to estimate the population genetic structure of Gonatocerus ashmeadi (Girault) (Hymenoptera: Mymaridae), the predominant egg parasitoid of Homalodisca coagulata (Say) (Homoptera:Cicadellidae), the glassy-winged sharpshooter. Six populations from throughout the U.S. and a population from Argentina identified as near G. ashmeadi were analyzed. Four populations (California; San Antonio, Texas; Weslaco, Texas [WTX-2]; and Florida) were field collected and two (Louisiana and Weslaco, Texas [WTX-1]) were reared. Three ISSR-PCR reactions were pooled to generate 41 polymorphic markers among the six U.S. populations. Nei's expected heterozygosity values (h), including the reared population from Louisiana, were high (9.01-14.3%) for all populations, except for a reared population from WTX-1 (2.9%). The total genetic diversity value (Ht) for the field populations was high (23%). Interestingly, the Florida population that was collected from one egg mass (siblings) generated the greatest number of polymorphic markers (20) and was observed with the highest gene diversity value (14.3%). All populations, except WTX-2 generated population-specific markers. Comparison of genetic differentiation estimates, which evaluate the degree of genetic subdivision, demonstrated good agreement between G(ST) and theta values, 0.38 and 0.50, respectively for field populations, and 0.44 and 0.50, respectively for all populations. Genetic divergence (D) indicated that the WTX-1 population was the most differentiated. Average D results from the Argentina population support the taxonomic data that it is a different species. The present results estimate the population genetic structure of G. ashmeadi, demonstrating genetic divergence and restricted gene flow (Nm = 0.83) among populations. These results are of interest to the Pierce's disease/glassy-winged sharpshooter biological control program because the key to successful biological control may not be in another species, but instead in different geographic races or biotypes.
对同一物种的不同天敌种群进行基因比较的目的是确定最适应其释放环境的品系。在本研究中，利用简单序列重复区间-聚合酶链反应（ISSR-PCR）来评估阿氏食虱跳小蜂（Gonatocerus ashmeadi）（膜翅目：跳小蜂科）的种群遗传结构，阿氏食虱跳小蜂是葡萄根瘤蚜（Homalodisca coagulata）（同翅目：叶蝉科）的主要卵寄生蜂，葡萄根瘤蚜又称玻璃翅叶蝉。分析了来自美国各地的6个种群以及来自阿根廷的一个被鉴定为接近阿氏食虱跳小蜂的种群。4个种群（加利福尼亚州；得克萨斯州圣安东尼奥市；得克萨斯州韦斯拉科市[WTX - 2]；以及佛罗里达州）是野外采集的，2个种群（路易斯安那州和得克萨斯州韦斯拉科市[WTX - 1]）是饲养的。3次ISSR-PCR反应合并后，在6个美国种群中产生了41个多态性标记。除WTX - 1的饲养种群（2.9%）外，所有种群（包括来自路易斯安那州的饲养种群）的内氏预期杂合度值（h）都很高（9.01 - 14.3%）。野外种群的总遗传多样性值（Ht）很高（23%）。有趣的是，从一个卵块（同胞个体）采集的佛罗里达州种群产生的多态性标记数量最多（20个），且观察到的基因多样性值最高（14.3%）。除WTX - 2外，所有种群都产生了种群特异性标记。评估遗传细分程度的遗传分化估计值的比较表明，G(ST)值和theta值之间具有良好的一致性，野外种群的G(ST)值和theta值分别为0.38和0.50，所有种群的分别为0.44和0.50。遗传距离（D）表明WTX - 1种群的分化程度最高。来自阿根廷种群的平均D结果支持了其为不同物种的分类学数据。目前的结果估计了阿氏食虱跳小蜂的种群遗传结构，表明种群间存在遗传分化和有限的基因流（Nm = 0.83）。这些结果对于葡萄根瘤蚜/玻璃翅叶蝉生物防治项目具有重要意义，因为成功进行生物防治的关键可能不在于引入另一个物种，而在于引入不同的地理种群或生物型。
