# Liu-pao Tea as a Source of Botanical Oviposition Attractants for Aedes Mosquitoes

## TL;DR

Liu-pao tea strongly attracts Aedes mosquitoes, offering a new tool for controlling diseases like dengue and Zika.

## Contribution

Identifies aged Liu-pao tea as a potent botanical oviposition attractant for Aedes mosquitoes, independent of microbes.

## Key findings

- Aged Liu-pao tea at 5 g/L strongly attracts Aedes albopictus with an oviposition activity index (OAI) of 0.73–0.67.
- A 0.5 g/L Liu-pao tea solution aged 21–28 days also effectively attracts Aedes aegypti with an OAI of 0.89.
- The attraction is due to volatile chemicals in the tea, not microbes, with cedrol contributing but not being as effective as the full tea solution.

## Abstract

Diseases transmitted by Aedes mosquitoes, including dengue, Zika, and chikungunya, lack effective vaccines and specific treatments, making vector control critical for disease prevention. Oviposition attractants offer a promising tool for managing mosquito populations. Effective oviposition attractants for Aedes mosquitoes are urgently needed. While green tea attracts Aedes aegypti, it is unclear how different tea fermentations affect the Asian tiger mosquito (Aedes albopictus). We tested teas across fermentation stages, evaluating attraction, the role of microbes, and chemicals. Results showed aged Liu-pao tea strongly attracts them at 5 g/L after 1–2 weeks. Notably, even a weak Liu-pao (0.5 g/L) solution successfully attracted Ae. aegypti mosquitoes with an oviposition activity index (OAI) of 0.89 (day 21). Crucially, we discovered that this attraction was not due to living microbes in the tea water, but rather natural chemicals released from the tea leaves. Also, we identified one specific chemical, cedrol, as part of this attraction, but found that the full tea solution worked much better than cedrol alone. These findings establish Liu-pao tea as a potent botanical attractant and support the development of multi-volatile “attract-and-kill” strategies for gravid Aedes mosquitoes.

Oviposition attractants can enhance both the surveillance and control of container-breeding Aedes mosquitoes. Although green tea has been reported to attract Ae. aegypti, the specific bioactive botanical compounds responsible remain unidentified. We evaluated teas across fermentation stages (non-fermented, fully fermented, and post-fermented) at 5 g/L for gravid Ae. albopictus using dual-choice assays. The most attractive tea (Liu-pao) was further tested across concentrations (0.5–5 g/L) and infusion ages (1–28 days). Autoclaved vs. non-autoclaved infusions assessed microbial contributions, while headspace volatiles were analyzed via HS-SPME-GC-MS. Individual compounds (cedrol and linalool oxide) were bioassayed. Only Liu-pao tea consistently attracted Ae. albopictus (OAI ≥ 0.3), peaking at 5 g/L after 7–14 days (OAIs 0.73/0.67). A 0.5 g/L infusion aged 21–28 days also attracted Ae. aegypti (OAIs 0.89/0.63). Autoclaving did not reduce attraction, confirming volatile compounds, not live microbe-mediated effects. Cedrol (1 mg/L) elicited moderate attraction (OAI 0.29) in Ae. albopictus, while linalool oxide was inactive. Post-fermented Liu-pao tea acts as a potent botanical attractant for Aedes mosquitoes. Cedrol contributes partially, but whole tea infusions outperform single compounds. These findings support developing multi-volatile “attract-and-kill” strategies targeting gravid mosquitoes.