Hybridization between eastern and western lineages of the biological control agent, Leucotaraxis argenticollis (Zetterstedt) (Diptera: Chamaemyiidae), was demonstrated in the laboratory. The western lineage is abundant on hemlock woolly adelgid, Adelges tsugae Annand (Hemiptera: Adelgidae) in western North America while a genetically distinct eastern lineage feeds mostly on pine adelgids (Hemiptera: Adelgidae: Pineus spp.). Western flies have been released in eastern North America but establishment has not been observed. When reared on A. tsugae in the laboratory, many eastern L. argenticollis larvae did not survive, and of those that did reach pupariation, 21% survived to the adult stage. To assess hybridization, eastern females were placed with western males for no-choice mating. They produced hybrid offspring with 8% survival to the adult stage when reared on A. tsugae. Further investigation of hybrid fitness, assortative mating, and the prey-seeking strategies of Leucotaraxis would aid in predicting the outcome of potential hybridization in the field.

Keywords: HWA; forest pest; no-choice test; silver fly.

Published by Oxford University Press on behalf of Entomological Society of America 2025.

实验室中证明了生物控制剂 Leucotaraxis argenticollis (Zetterstedt)（双翅目：Chamaemyiidae）东部和西部谱系之间的杂交。西部谱系在北美西部的日本五针松蚜虫 Adelges tsugae Annand （半翅目：Adelgidae）上非常丰富，而一个基因上不同的东部谱系主要以松树蚜虫（半翅目：Adelgidae：Pineus spp.）为食。西部苍蝇已在美国东部地区释放，但尚未观察到建立种群的情况。在实验室中用 A. tsugae 培养时，许多东部 L. argenticollis 幼虫没有存活下来，而在那些成功达到蛹期的个体中，只有 21% 存活到了成虫阶段。为了评估杂交情况，将东部雌性与西部雄性配对进行无选择交配实验。当在 A. tsugae 上培养时，它们产生的杂交后代仅有 8% 的存活率达到了成虫阶段。进一步研究杂交适应度、同种配偶选择以及 Leucotaraxis 的猎物搜寻策略将有助于预测野外潜在杂交情况的结果。

关键词： HWA；森林害虫；无选择测试；银蝇。

由牛津大学出版社代表美国昆虫学会出版 2025 年。