Bittner James A, Balfe Susan, Pittendrigh Barry R, Popovics John S
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Champaign, IL.
Department of Entomology, Michigan State University, East Lansing, MI.
J Econ Entomol. 2018 May 28;111(3):1469-1475. doi: 10.1093/jee/toy086.
Cowpea provides a significant source of protein for over 200 million people in Sub-Saharan Africa. The cowpea bruchid, Callosobruchus maculatus (F) (Coleoptera: Bruchidae), is a major pest of cowpea as the larval stage attacks stored cowpea grains, causing postharvest loss. Cowpea bruchid larvae spend all their time feeding within the cowpea seed. Past research findings, published over 25 yr ago, have shown that feeding activity of several bruchids within a cowpea seed emit mechanical vibrations within the frequency range 5-75 kHz. This work led to the development of monitoring technologies that are both important for basic research and practical application. Here, we use newer and significantly improved technologies to re-explore the nature of the vibration signals produced by an individual C. maculatus, when it feeds in cowpea seeds. Utilizing broadband frequency sensing, individual fourth-instar bruchid larvae feeding activities (vibration events) were recorded to identify specific key emission frequencies. Verification of recorded events and association to actual feeding activities was achieved through mass measurements over 24 h for a series of replicates. The measurements identified variable peak event emission frequencies across the replicate sample set ranging in frequency from 16.4 to 26.5 kHz. A positive correlation between the number of events recorded and the measured mass loss of the cowpea seed was observed. The procedure and verification reported in this work provide an improved basis for laboratory-based monitoring of single larval feeding. From the rich dataset captured, additional analysis can be carried out to identify new key variables of hidden bruchid larval activity.
豇豆为撒哈拉以南非洲地区超过2亿人提供了重要的蛋白质来源。豇豆象鼻虫，即黄斑豆象（Callosobruchus maculatus (F)，鞘翅目：豆象科），是豇豆的主要害虫，因为其幼虫阶段会攻击储存的豇豆籽粒，导致收获后损失。豇豆象鼻虫幼虫一生都在豇豆种子内取食。25多年前发表的以往研究结果表明，豇豆种子内几种豆象的取食活动会发出频率范围在5 - 75千赫兹的机械振动。这项工作促成了监测技术的发展，这些技术对基础研究和实际应用都很重要。在此，我们使用更新且显著改进的技术，重新探索单个黄斑豆象在豇豆种子内取食时产生的振动信号的性质。利用宽带频率传感，记录了单个四龄豆象幼虫的取食活动（振动事件），以确定特定的关键发射频率。通过对一系列重复样本进行24小时的质量测量，实现了对记录事件的验证以及与实际取食活动的关联。测量结果确定了重复样本集中不同的峰值事件发射频率，范围在16.4至26.5千赫兹之间。观察到记录的事件数量与豇豆种子测量的质量损失之间存在正相关。这项工作中报告的程序和验证为基于实验室的单个幼虫取食监测提供了改进的基础。从捕获的丰富数据集中，可以进行进一步分析，以识别隐藏的豆象幼虫活动的新关键变量。
