Competition between biological control fungi and fungal symbionts of ambrosia beetles Xylosandrus crassiusculus and X. germanus (Coleoptera: Curculionidae): Mycelial interactions and impact on beetle brood production
Competition between biological control fungi and fungal symbionts of ambrosia beetles Xylosandrus crassiusculus and X. germanus (Coleoptera: Curculionidae): Mycelial interactions and impact on beetle brood production
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DOI：
10.1016/j.biocontrol.2016.09.005
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发表时间：
2016-12-01
影响因子：
4.2
通讯作者：
Vandenberg, John D.
中科院分区：
文献类型：
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作者：
Castrillo, Louela A.;Griggs, Michael H.;Vandenberg, John D.
木沙甲虫和德国X. germanus是美国果园和苗圃中最重要的外来害虫，由于它们的隐蔽习性，使用常规杀虫剂很难控制。生物防治剂的使用可能被证明是有效的，可以同时针对树洞内的甲虫和真菌共生体：昆虫病原真菌可以用来针对甲虫的孵化者和它们的后代，或者分枝真菌，例如哈茨木霉，可以用来针对它们相关的真菌共生体。采用体外实验和甲虫生物实验相结合的方法，研究了共生体与生物防治真菌之间的竞争以及生物防治真菌对甲虫产卵的影响。体外资源捕获试验结果表明，哈茨芽孢杆菌在一次或二次资源捕获试验中分别优于与粗制棘球绦虫和德国棘球绦虫相关的罗氏Ambrosiella roeperi和gromanniae菌株。相比之下，昆虫病原真菌球孢白僵菌和绿僵菌仅在初级竞争分析中阻止共生体的传播。互补的甲虫生物测定表明，在T. harzianum处理过的山毛榉茎中，甲虫廊有稀疏的共生生长，许多没有或只有少量的卵存在。在哈兹兰处理过的茎中，雌蜂产生的卵数与用较高剂量的昆虫病原体处理过的茎中的卵数相当，在这种情况下，产卵减少可能是由于雌蜂在产卵前或只产卵少量后死亡。这些结果表明，利用生物防治真菌直接杀死雌虫并减少产卵量或间接抑制其通道内共生体的生长，都有可能针对神仙甲虫种群。(C) 2016 Elsevier Inc.版权所有。
Ambrosia beetles Xylosandrus crassiusculus and X. germanus are among the most important exotic pests of orchards and nurseries in the US and are difficult to control using conventional insecticides because of their cryptic habits. The use of biological control agents may prove effective by targeting both beetles and fungal symbionts inside tree galleries: entomopathogenic fungi could be used to target beetle foundresses and their brood, or mycoparasitic fungi, e.g., Trichoderma harzianum, could be used to target their associated fungal symbionts. We used a combination of in vitro assays and beetle bioassays to examine competition between symbionts and biological control fungi and the impact of biological control fungi on beetle brood production. The in vitro assays showed T. harzianum outcompeted different strains of Ambrosiella roeperi and A. grosmanniae associated with X. crassiusculus and X. germanus, respectively, whether in primary or secondary resource capture assays. In contrast, entomopathogenic fungi Beauveria bassiana and Metarhizium brunneum blocked the spread of symbionts only in primary competition assays. Complementary beetle bioassays showed that beetle galleries in T. harzianum-treated beech stems had sparse symbiont growth, many with no or only a small number of eggs present. Brood numbers produced by foundresses in T. harzianum-treated stems were comparable to those in stems treated with either entomopathogen at the higher dosages, in which brood reduction was likely due to foundress mortality prior to laying eggs or after laying only a small number of eggs. These results show the potential of using biological control fungi in targeting ambrosia beetle populations either directly by killing foundresses and reducing brood production or indirectly by suppressing symbiont growth in their galleries. (C) 2016 Elsevier Inc. All rights reserved.