Abstract
Simple SummaryThe 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.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.
Highlights
Oviposition behavior is important among many insect taxa for ontogeny, reproduction, and maintaining their population in an ecosystem
Observations of the egg laying videos recorded in the laboratory clearly indicated that gravid females of E. onukii can oviposit inside all parts of the tender shoots, including stem, leaf petiole, and vein
The largest E. onukii eggs in each cultivar were all oviposited at the third leaf position, and the proportions of blue light detection method (BLDM)/stereomicroscope detection method (SMDM) at this site in Longjing 43, Maoxie, Huangjinya and Zijuan were 95.93%, 99.29%, 100%, and 96%, respectively (Table 3). These results demonstrate that E. onukii eggs deposited at higher leaf positions on tea shoots can be as accurately detected by the simpler method of blue light as by dissection
Summary
Oviposition behavior is important among many insect taxa for ontogeny, reproduction, and maintaining their population in an ecosystem. The dynamism of egg laying in different insect species has application to their life history, behavioral habits, reproductive strategies, and evolutionary patterns, with both theoretical and practical value. The study of oviposition behavior provides a better understanding of bionomics for agricultural and forestry pests, and can contribute to a more effective and sustainable pest prevention and management approaches [1,2]. The adults and nymphs damage the tender tea shoots by piercing into and sucking sap leading to “hopperburn”. Symptoms on infested shoots of tea plants [5]. Adult female E. onukii often insert their eggs into the epidermis of tender stems, causing hopperburn symptoms that, when combined with feeding damage, leads to a 50–70% yield reduction [6]
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