咖啡因對孤雌胎生豌豆蚜之生殖發育影響

Abstract

以咖啡樹 (咖啡屬，Coffea 之植物) 為食的昆蟲種類繁多，超過850種昆蟲被記錄為咖啡樹的害蟲。其中，已記錄的蚜蟲有三種，分別是桃蚜 (Myzus persicae)、棉蚜 (Aphis gossypii) 和小桔蚜 (Toxoptera aurantii)。然而，有關蚜蟲代謝咖啡因的機制，以及咖啡因對蚜蟲發育和生殖能力影響的研究仍非常匱乏。僅有的研究顯示，在人工飼料中添加0.1 mg/ml 咖啡因，能使桃蚜成蟲的產子數量減少42%，壽命縮短30%。因此，探討咖啡因如何影響蚜蟲的生殖發育，是一個重要的研究議題。 本研究旨在通過人工飼料餵食蚜蟲不同濃度的咖啡因，了解其對蚜蟲各項生理指標及卵巢發育狀況的影響，以填補目前咖啡因與蚜蟲之間研究的空白。我們選取豌豆蚜 (Acyrthosiphon pisum) 作為研究對象，在其人工飼料中添加0.00、0.10、0.12、0.14、0.16、0.18及0.20 mg/ml 咖啡因進行飼養實驗。結果發現，隨著咖啡因濃度的增加，蚜蟲的成蟲率顯著下降，發育時間顯著延長，成蟲體重和體型顯著減輕。在生殖能力方面，咖啡因導致蚜蟲繁殖能力顯著下降，甚至出現不育個體 (成蟲在未產下若蟲的情況下死亡)。解剖實驗進一步顯示，咖啡因減緩了蚜蟲卵巢的發育速度，使卵巢顯著縮小。然而，咖啡因並未減少蚜蟲卵巢中的蛋腔數量，卵巢縮小的主要原因是胚胎發育遲緩。在0.20 mg/ml 咖啡因處理下，最成熟的胚胎僅達到第15期。此外，咖啡因還導致蚜蟲卵巢出現畸形結構，胚胎無法發育甚至缺乏生殖細胞。 另外，我們對蚜蟲進行抗生素處理，探討咖啡因對去共生及正常蚜蟲的影響。即使在最低劑量的咖啡因處理下，幾乎所有去共生蚜蟲均出現不育狀況。本研究結果為咖啡因對蚜蟲的生理及生殖影響提供了重要數據，並為進一步的研究奠定了基礎。了解咖啡因對蚜蟲的生理和生殖影響，可為發展新的生物農藥提供理論依據。咖啡因作為一種天然植物殺蟲劑，具有潛力成為控制蚜蟲的重要工具。

Coffee plants (genus Coffea) host over 850 species of insect pests, including three documented aphid species: green peach aphid (Myzus persicae), cotton aphid (Aphis gossypii), and black citrus aphid (Toxoptera aurantii). Despite this, research on aphid caffeine metabolism and the effects of caffeine on aphid development and reproduction remains scarce. Existing studies show that adding 0.1 mg/ml of caffeine to artificial diets reduces adult M. persicae offspring by 42% and shortens lifespan by 30%. This study aims to investigate how caffeine affects aphid reproductive development to fill this research gap. We selected the pea aphid (Acyrthosiphon pisum) and conducted feeding experiments with artificial diets containing 0.00, 0.10, 0.12, 0.14, 0.16, 0.18, and 0.20 mg/ml of caffeine. Results indicate that higher caffeine concentrations significantly decrease adult aphid rates, increase development time, and reduce adult weight and size. Caffeine also significantly lowers reproductive capacity, with some individuals becoming infertile (dying without producing nymphs). Dissection revealed that caffeine slows ovarian development, causing significant size reduction without reducing oocyte numbers. The primary cause of reduced ovarian size was delayed embryonic development, with the most mature embryos reaching only the 15th stage at 0.20 mg/ml caffeine. Additionally, caffeine induced ovarian structural deformities, preventing proper embryo development and resulting in a lack of germ cells. Furthermore, antibiotic treatments showed that nearly all aposymbiotic aphids became infertile even at the lowest caffeine concentrations. This study provides essential data on caffeine's physiological and reproductive effects on aphids, laying a foundation for further research. Understanding these effects can support the development of new biopesticides, positioning caffeine as a potential natural insecticide for aphid control.