Avery Pasco B, Bojorque Verónica, Gámez Cecilia, Duncan Rita E, Carrillo Daniel, Cave Ronald D
Indian River Research and Education Center, IFAS, University of Florida, 2199 South Rock Road, Ft. Pierce, FL 34945, USA.
Escuela Agrícola Panamericana, P.O. Box 93 Tegucigalpa, Honduras.
Insects. 2018 Apr 25;9(2):49. doi: 10.3390/insects9020049.
Laurel wilt is a disease threatening the avocado industry in Florida. The causative agent of the disease is a fungus vectored by ambrosia beetles that bore into the trees. Until recently, management strategies for the vectors of the laurel wilt fungus relied solely on chemical control and sanitation practices. Beneficial entomopathogenic fungi (EPF) are the most common and prevalent natural enemies of pathogen vectors. Laboratory experiments demonstrated that commercial strains of EPF can increase the mortality of the primary vector, , and potential alternative vectors, , and (Coleoptera: Curculionidae: Scolytinae). Our study provides baseline data for three formulated commercially-available entomopathogenic fungi used as potential biocontrol agents against , and The specific objectives were to determine: (1) the mean number of viable spores acquired per beetle species adult after being exposed to formulated fungal products containing different strains of EPF (, and ); and (2) the median and mean survival times using paper disk bioassays. Prior to being used in experiments, all fungal suspensions were adjusted to 2.4 × 10⁶ viable spores/mL. The number of spores acquired by was significantly higher after exposure to , compared to the other fungal treatments. For , the numbers of spores acquired per beetle were significantly different amongst the different fungal treatments, and the sequence of spore acquisition rates on from highest to lowest was > > . After beetles were exposed to the different suspensions, the rates of acquisition of spores per beetle amongst the different fungal treatments were similar. Survival estimates (data pooled across two tests) indicated an impact for each entomopathogenic fungus per beetle species after exposure to a filter paper disk treated at the same fungal suspension concentration. Kaplan⁻Meier analysis (censored at day 7) revealed that each beetle species survived significantly shorter in bioassays containing disks treated with EPF compared to water only. This study demonstrated that ambrosia beetles associated with the laurel wilt pathogen in avocados are susceptible to infection by EPF under laboratory conditions. However, the EPF needs to be tested under field conditions to confirm their efficacy against the beetles.
月桂枯萎病是一种威胁佛罗里达州鳄梨产业的病害。该病的病原体是一种由蛀入树木的小蠹虫传播的真菌。直到最近，月桂枯萎病菌载体的管理策略仅依赖于化学防治和卫生措施。有益的昆虫病原真菌（EPF）是病原体载体最常见和普遍的天敌。实验室实验表明，EPF的商业菌株可提高主要载体以及潜在替代载体、 和 （鞘翅目：象甲科：小蠹亚科）的死亡率。我们的研究为三种商业化生产的昆虫病原真菌制剂提供了基线数据，这些制剂用作针对 、 和 的潜在生物防治剂。具体目标是确定：（1）暴露于含有不同EPF菌株（ 、 和 ）的真菌制剂后，每种甲虫成虫获得的活孢子平均数量；（2）使用纸盘生物测定法的中位和平均存活时间。在用于实验之前，将所有真菌悬浮液调整至2.4×10⁶个活孢子/毫升。暴露于 后， 获得的孢子数量明显高于其他真菌处理。对于 ，不同真菌处理下每只甲虫获得的孢子数量存在显著差异， 上孢子获取率从高到低的顺序为 > > 。 只甲虫暴露于不同悬浮液后，不同真菌处理下每只甲虫的孢子获取率相似。存活估计（两项试验汇总的数据）表明，暴露于相同真菌悬浮液浓度处理的滤纸盘后，每种昆虫病原真菌对每种甲虫都有影响。Kaplan-Meier分析（在第7天进行删失）显示，与仅用水处理的生物测定相比，在含有用EPF处理的纸盘的生物测定中，每种甲虫的存活时间显著缩短。这项研究表明，在实验室条件下，与鳄梨月桂枯萎病病原体相关的小蠹虫易受EPF感染。然而，EPF需要在田间条件下进行测试，以确认它们对甲虫的防治效果。
