施用免登記植物保護資材對基徵草蛉 (Mallada basalis) 之風險與綜合應用研究

Abstract

農藥是病蟲害防治中的一大利器，但僅有少部分抵達作用位置，其餘的會留存於環境中；免登記植物保護資材相對於農藥毒性較低且於環境中殘留性較小，但仍不可忽視其對於非目標生物的影響。因此本研究評估三種免登記植物保護資材—柑橘精油、肉桂精油與苦楝油對商品化天敵昆蟲基徵草蛉 (Mallada basalis) 的急毒性、行為反應與生理影響，模擬其在田間透過體表接觸、呼吸揮發物及攝食三種可能接觸途徑，觀察並記錄各資材於不同途徑下造成的死亡率。體表接觸試驗顯示，苦楝油對基徵草蛉一齡幼蟲具最高毒性，其次為肉桂精油與柑橘精油，但三者均屬於國際生物防治組織 (IOBC) 毒性分級中的「無毒害」等級。揮發物呼吸試驗亦顯示類似趨勢，苦楝油死亡率最高，柑橘精油最低，三者對基徵草蛉卵孵化率無影響。在捕食毒性試驗中，肉桂精油顯著降低基徵草蛉對蚜蟲的捕食行為並提升死亡率，屬於「低毒性」等級，其餘兩資材則無顯著負面影響。忌避行為方面，肉桂精油與苦楝油於試驗初期引發短暫低忌避性，但在1~4小時內因揮發與分解作用導致忌避性消失。多次暴露試驗結果指出，肉桂精油會減少幼蟲體重增加幅度，而苦楝油則顯著降低總存活率，惟三種資材對幼蟲發育天數與雌性比皆無顯著影響。綜合而言，柑橘精油在各項試驗中皆未對基徵草蛉造成顯著不良影響，為較安全之資材。相對地，肉桂精油與苦楝油雖毒性較低，仍可能於某些條件下對基徵草蛉生理與行為產生影響，因此在實際應用於IPM (整合性病蟲害管理) 策略時，應謹慎考量使用濃度與施藥時機，以兼顧作物防治與天敵施用效益。

Pesticides are powerful tools in pest management, yet only a small proportion reaches the target site, while the remainder may persist in the environment. Compared to conventional pesticides, plant protection materials exempted from registration typically exhibit lower toxicity and reduced environmental persistence. However, their potential impacts on non-target organisms should not be overlooked. This study evaluated the acute toxicity, behavioral responses, and physiological effects of three such materials—citrus essential oil, cinnamon essential oil, and neem oil—on the commercially available predatory insect Mallada basalis (Neuroptera: Chrysopidae). Three potential exposure routes were simulated: direct contact via cuticle, inhalation of volatiles, and ingestion through predation. Mortality rates under each route were recorded accordingly. In contact toxicity assays, neem oil caused the highest mortality in first-instar larvae, followed by cinnamon and citrus oils. Nonetheless, all three were classified as “harmless” under IOBC toxicity categories. A similar trend was observed in inhalation exposure assays, where neem oil again resulted in the highest larval mortality, and citrus oil the lowest, with no significant effect on egg hatchability. In predation toxicity assays, cinnamon oil significantly reduced aphid consumption and increased larval mortality, placing it in the “slightly harmful” category, while the other two oils showed no notable adverse effects. In repellency assays, cinnamon and neem oils exhibited low-level repellency within the first 30 minutes, but the effect diminished within 1–4 hours due to volatility and oxidative degradation. Under repeated exposure, cinnamon oil was found to reduce larval weight gain, whereas neem oil significantly decreased total viability. However, none of the three oils significantly affected larval development duration or adult female ratio. In conclusion, citrus essential oil exhibited no significant negative effects across all test parameters, indicating it is relatively safe for M. basalis. By contrast, although cinnamon and neem oils showed low toxicity overall, they may still influence the physiology and behavior of M. basalis under certain conditions. Therefore, when incorporating these materials into integrated pest management (IPM) strategies, it is essential to carefully consider their application concentrations and timing to balance pest control efficacy with natural enemies.