二點葉蟎大量繁殖及其應用

Abstract

本論文進行二點葉蟎(Tetranychus urticae Koch)大量繁殖及其應用研究，二點葉蟎以台灣本土大豆品系-綠肥作物青皮豆飼養，分別在實驗室及溫室中進行大量繁殖，室內繁殖條件設為26 ± 1℃、65％∼95％ RH及光照14：10 h (L：D)。室內繁殖葉蟎每單位面積(30 x 60 cm)最大繁殖量發生在接種後第10∼11天，可繁殖538,000∼543,000隻葉蟎，此時葉蟎卵粒及幼蟎含量大於70%，試驗結果建議葉蟎最佳收穫期為繁殖後第10∼11天。在溫室大量繁殖方面，試驗1每單位面積接種100,000隻葉蟎時，在接種後第8天時族群為851,000隻；試驗2每單位面積接種60,000隻葉蟎時，在第9天時族群為744,000隻，但2次繁殖試驗卵粒及幼蟎最大量皆出現在第8天，分別為672,290及561,600隻，所以試驗結果建議溫室繁殖葉蟎最佳收獲期為繁殖後第8天。再來利用搖篩分離方式可將葉蟎與青皮豆植株分離，以豆株600株，搖篩1分鐘，葉蟎各生命期分離率皆大於50%，殘株可再利用重新接種乾淨青皮豆豆株，循環利用，非常方便。葉蟎繁殖應用方面，首先以水盤方式，利用二點葉蟎繁殖其天敵智利捕植蟎(Phytoseiulus persimilis Athias-Henriot)，飼育條件設為26 ± 1℃、65%∼95% RH及光照14：10 (L：D) h。智利捕植蟎以160倍的葉蟎繁殖，其族群最大增加量發生於第11、13及14天，捕植蟎數分別增加19.6、22.9及15.4倍，載台上殘留葉蟎與捕植蟎之比率分別為33、5.5及6.4。第15天後捕植蟎數降低到7.7倍以下，試驗結果建議捕植蟎最佳收穫期為繁殖後第13∼14天。另外考量以捕植蟎防治葉蟎時應在葉蟎低密度時釋放，所以進行非農藥防治研究以先行降低田間葉蟎密度。葉蟎繁殖應用另ㄧ方面即進行皂液對二點葉蟎的致死影響研究，選取五種市售家用肥皂加水稀釋成皂液，在實驗室內使用葉浸法對二點葉蟎雌成蟎及卵粒進行觸殺及殘毒生物檢定，評估皂液對葉蟎的致死影響。結果顯示雌成蟎浸泡於不同皂液(4 g (AI)/l) 1∼8秒，處理時間之死亡率為93.1%∼98.6%差異不顯著，與浸泡於對照藥劑阿巴汀(0.01 g (AI)/l)的死亡率(100%)也無顯著差異。卵粒分別浸泡皂液與蒸餾水後之孵化率差異不顯著，孵化後若蟎再次浸泡皂液之死亡率為89.2%∼98.8%，故也無法完全將若蟎殺除。雌成蟎經由肥皂殘毒生物檢定，結果顯示肥皂殘毒試驗的雌成蟎與用蒸餾水試驗的死亡率無顯著差異。皂液中之二價金屬離子濃度也會影響對二點葉蟎的殺蟎效果，將雌成蟎浸泡於以標準硬水為溶劑的肥皂水溶液，其死亡率皆低於浸泡於以蒸餾水為溶劑的皂液，且差異顯著。

In this study, we developed a system for the mass production of the two-spotted spider mite, Tetranychus urticae Koch in the laboratory and in a greenhouse. First, T. urticae was reared on soybeans (Chin-pe Tao, a native soybean variety) hydroponically without nutrients in the laboratory at 26 ± 1℃ and 65％-95％ RH, under a 14: 10-h (L: D) photoperiod. The greatest numbers of spider mites per bean seedling were 909-962 on days 10-11. The greatest numbers of spider mites per rearing unit (30 x 60 cm) were 538,000-543,000 for feeding on ca. 600 bean seedlings on days 10-11. The frequencies of T. urticae eggs and larvae on bean seedlings were over 70%. It is recommended that the optimal harvesting time for rearing T. urticae is on days 10-11. Second, T. urticae was reared on soybeans hydroponically without nutrients in a greenhouse and were extracted from bean seedlings using a vibratory sieve shaker. In experiment I, the greatest number of spider mites per rearing unit (30 x 60 cm) was 851,000 on day 8 and showed an 8.51-fold increase to the initially inoculated 100,000 individuals. In experiment II, the greatest number of spider mites per rearing unit was 744,000 on day 9 and showed a 12.4-fold increase to the initially inoculated 60,000 individuals. The greatest yield of T. urticae eggs and larvae per rearing unit appeared on day 8 in both experiments I (672,290 individuals) and II (561,600 individuals). It is recommended that the optimal harvesting time for the mass production of T. urticae is on day 8. All life stages of the residual population of T. urticae on bean seedlings after extraction can be used to re-infest new host plants. They recover very well. The yield and extraction rate of spider mites can be predicted. The population densities of T. urticae were significantly correlated with the rearing period for the linear regression. Regression analyses showed a significant logarithmic relationship between the extraction rate of T. urticae and the vibration time. An extraction-reproduction cycle was established. The operating time is very short, and most importantly, the spider mites are alive. Third, Phytoseiulus persimilis was reared in arenas set up established in the laboratory at 26 ± 1℃ and 65％-95％ RH, under a 14: 10-h (L: D) photoperiod. The population of P. persimilis feeding on a 160-fold greater number of T. urticae showed the greatest increase on day 13, an average of 22.9-fold. The ratio of T. urticae to P. persimilis was 5.5. After day 15, the population increase of P. persimilis feeding on a 160-fold greater number of T. urticae was lower than 7.7-fold per arena. It is recommended that the optimal harvesting time for rearing of P. persimilis is on days 13-14. Finally, this study also assessed on the control effect of soap solution on T. urticae. Five kinds of soap solutions (4 g (AI)/l) made by different household soap were evaluated by contact and residual bioassays on the adult and egg stages of T. urticae in the laboratory. The mortalities of female adults immersed in each soap solution for 1 to 8 s exhibited no significant difference, and treated by soap (4 g (AI)/l) in distilled water, or by abamectin (0.01 g (AI)/l), the mortalities also exhibited no significant difference. The mortalities of female adults ranged from 93.1% to 98.6% among five soap solutions and that of abamectin solution was 100%. Soap solutions did not significantly affect T. urticae egg hatchability, and sequential second dipping could not completely eradicate the remaining nymphs. The mortality of nymphs ranged from 89.2% to 98.8% among those soap solutions. Soap residual bioassay showed that residues did not significantly affect the mortality of female adults as well. Divalent metal ion concentrations in soap solution could affect the soap activity on T. urticae. The mortality of female adults using each kind of soap dissolved in standard hard water was significantly lower than that same soap dissolved in distilled water.