ABSTRACT

In 2013, cereal leaf beetle was reported for the first time in California. Most likely it moved south from Oregon into the state’s northern region. In response, the gregarious larval endoparasitoid Tetrastichus julis (Hymenoptera: Eulophidae) was collected and transferred to a field insectary at the University of California Intermountain Research and Extension Center in Tulelake. From 2014 to 2018 the insectary was maintained to propagate T. julis for redistribution to commercial grain fields in northern California experiencing infestations by this pest. Sequential plantings of oats, preceded by winter wheat at this insectary provided a constant source of pre-head, lush oats throughout the summer. In turn, a reliable source of cereal leaf beetle hosts was produced for T. julis, which also increased in numbers. These parasitoids were released into infested commercial fields of wheat in the Klamath Basin region of northern California. Over four years beginning in 2016, annual surveys of the region showed that cereal leaf beetle populations declined while T. julis rapidly increased. Our releases, in addition to the natural spread of this parasitoid south from Oregon played a key role in the beetle population declining by nearly 90% over this period.

摘要

2013 年，加利福尼亚州首次报道了谷叶甲虫。它很可能从俄勒冈州向南移动到该州的北部地区。作为回应，收集了群居幼虫内寄生物Tetrastichus julis（膜翅目：Eulophidae）并将其转移到位于图莱莱克的加利福尼亚大学山间研究和推广中心的田间昆虫中。从 2014 年到 2018 年，该昆虫被维持以繁殖T. julis，然后再分配到北加州遭受这种害虫侵扰的商业粮田。在这个昆虫园连续种植燕麦，然后是冬小麦，在整个夏季提供了一个稳定的前头、茂盛的燕麦来源。反过来，谷类叶甲虫宿主的可靠来源是为T. julis，其数量也有所增加。这些寄生蜂被释放到加利福尼亚北部克拉马斯盆地地区受侵染的商业小麦田中。从 2016 年开始的四年多，对该地区的年度调查显示，谷叶甲虫种群数量下降，而T. julis迅速增加。我们的释放，除了这种从俄勒冈州南部自然传播的寄生蜂之外，在此期间甲虫种群减少了近 90% 方面发挥了关键作用。