Identifying the Biological Characteristics Associated with Oviposition Behavior of Tea Leafhopper Empoasca onukii Matsuda Using the Blue Light Detection Method

SIMPLE SUMMARY: The tea leafhopper (Empoasca onukii Matsuda) is currently one of the most threatening pests in tea gardens in China. To locate and count tea leafhopper eggs, stereomicroscopy is a conventional method by dissecting the tender tissues, which is both time- and labor-consuming. The scarcity of a verified method to directly observe and investigate intact eggs within tea shoots impedes the research efforts to test the oviposition behavior of E. onukii. Herein, comparing against the stereomicroscope detection method (SMDM), we evaluated the blue light detection method (BLDM), a technique recently developed for other species in detecting E. onukii eggs directly and non-destructively within the tender shoot for four tea cultivars. The conclusion indicated that BLDM could correctly measure the egg laying quantity of E. onukii on intact tea shoots, and its accuracy was not affected by both tea cultivars and egg density in the tender shoot. Furthermore, the biological characteristics concerning the oviposition behaviors that have rarely been reported previously for E. onukii were investigated using the BLDM. Our findings provide insights for the basic research and theoretical evidence, and allow the follow-up studies for the strategy and mechanism associated with the egg laying behavior of E. onukii. ABSTRACT: Tea leafhopper (Empoasca onukii Matsuda) is amongst the key pests in tea plantations around the East Asian region. Stereomicroscopy is a conventional method used for detecting tea leafhopper eggs by dissecting the tender tissues. However, there is a need for a faster and more efficient method to directly observe and investigate intact eggs within tea shoots. The absence of a proven method limits research efforts for determining the oviposition behavior of E. onukii. Herein, we applied the blue light detection method (BLDM), a technique recently developed for other species, in order to detect E. onukii eggs directly and non-destructively within the tender shoot. In addition, we compared BLDM against the traditional stereomicroscope detection method (SMDM) for four tea cultivars. Notably, our results revealed that BLDM was precise and effective in measuring the egg laying quantity of E. onukii on intact tea shoots. Neither tea cultivars nor egg density in the tender shoot significantly affected the accuracy of BLDM. Furthermore, biological characteristics that have rarely been reported previously for E. onukii were investigated using the BLDM, including zygote duration, ovipositional rhythm, egg distribution within the tender shoot, and in different leaf positions, numbers of eggs laid by a single female daily, and laid by the entire generation. Therefore, these findings provide insights into the basic and theoretical evidence for the strategy and mechanism associated with the oviposition behavior of E. onukii.