ABSTRACT

Japanese oak wilt is caused by the pathogen, which is introduced into oaks by the ambrosia beetle Platypus quercivorus of which male initiates to bore. In the field, the entrance holes of beetles have been observed primarily in bark crevices. We hypothesized that male P. quercivorus initially distinguish the bark surface structure and then determine the hole boring site. To test this hypothesis, we observed the initiation of hole boring behavior by P. quercivorus under laboratory conditions. We prepared pieces of Quercus alba with 21 crevice patterns created by changing the opening angle and gap width. Each wood piece was placed in a plastic case and a male P. quercivorus was introduced into the case following flight in a flight mill. The male beetles were monitored for 30 min and the following three behaviors were recorded: whether the beetle recognized the crevice, whether the beetle stayed in the crevice for more than 30 s, and whether the beetle bored a hole in the crevice. Generalized linear models were constructed to clarify which factors (angle and width) influencing beetle behavior. Model analysis revealed that gap width affected only the staying behavior, whereas the opening angle affected all three behaviors. The probabilities of these behaviors occurring increased with a decrease in opening angle, though this trend was weak in hole boring behavior. Our results indicate that P. quercivorus detects a suitable surface structure and subsequently determines the best hole boring site based on structural characteristics, particularly the angle of the crevice opening.

摘要

日本橡树枯萎病是由病原体引起的，病原体是由雄性不耐烦的甲虫桔梗（Platypus quercivorus）引入橡树的。在野外，主要在树皮缝隙中发现了甲虫的入口孔。我们假设雄性P. quercivorus最初会区分树皮表面结构，然后确定钻孔位置。为了验证这一假设，我们观察到了在实验室条件下由食蚁对虾引起的钻孔行为。我们准备了具有改变开口角度和缝隙宽度的21个缝隙图案的Quercus alba。将每个木块放在一个塑料盒中，然后放一个雄性的食蚁兽。是在一家飞行磨坊飞行后被引入该案件的。监测雄性甲虫30分钟，并记录以下三种行为：甲虫是否识别出缝隙；甲虫是否在缝隙中停留了30秒以上；甲虫是否在缝隙中打了一个洞。构建了广义线性模型，以阐明影响甲虫行为的因素（角度和宽度）。模型分析表明，缝隙宽度仅影响停留行为，而张开角度影响所有三种行为。这些行为发生的可能性随着打开角度的减小而增加，尽管这种趋势在钻孔行为中很弱。我们的结果表明，P。quercivorus 检测合适的表面结构，然后根据结构特征（尤其是缝隙开口的角度）确定最佳的钻孔位置。