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Interactions between Amblyseius ovalis (Evans) (Acarina: Phytoseiidae) and Bemisia argentifolii Bellows & Perring (Homoptera: Aleyrodidae) on Cucumber
|作者:||白桂芳||關鍵字:||卵形捕植;Amblyseius ovalis;銀葉粉蝨;胡瓜;族群介量;功能反應;空間分布;密度依變;生物防治;Bemisia argentifolii;cucumber;population parameter;functional response;spatial distribution;density dependent;biological control||出版社:||昆蟲學系||摘要:||
取食胡瓜之雌、雄性銀葉粉蝨（Bemisia argentifolii Bellows & Perring）在28 ℃自卵發育為成蟲需19.7日~ 19.9日，於25.6日之產卵期內可產101卵，每日每雌平均可產3.64卵，其產卵高峰出現於第4及第8日（6.52及6.02卵/雌/日），於世代時間（T = 29.6日）可增殖101.65倍（Ro），每日每雌之內在增殖率（rm）達0.156子代/雌/日。銀葉粉蝨於不同胡瓜品種之適應策略，係依發育速率及成蟲壽命而非繁殖率。卵形捕植Amblyseius ovalis（Evans）取食胡瓜花粉時，有68.8%的雌可完成發育，其一生產26.8卵/雌，每日平均產1.1卵/雌/日。產卵高峰出現於第4日齡及第8 ~ 10日齡，雌之壽命達24.4日，子代雌性比（♀/(♀＋♂)）為0.68。單以胡瓜花粉為食之雌雖完成發育，但有16.7 %的個體不產卵，於增補銀葉粉蝨若蟲後，則雌均恢復生殖能力。卵形捕植之發育時間、存活率、逃跑率及壽命均以捕食銀葉粉蝨一齡及二齡若蟲另添加花粉者為佳，此等雌均具100 %生殖能力，並顯著高於取食粉蝨卵或卵另添加花粉所發育之雌生殖力（50.0 % 或61.1 %）。供飼粉蝨二齡若蟲及花粉的雌產卵量最高，捕食粉蝨卵者最低；雌取食各食餌源的每日每雌產卵量介於0.1 ~ 1.3卵/雌/日，其間差異顯著（p = 0.05）。卵形捕植捕食銀葉粉蝨各齡期的族群淨增殖率（Ro）介於4.28 ~ 21.86之間，族群內在增殖率（rm）為0.140 ~ 0.288卵/♀♀/日，族群世代時間（T）則介於10.41 ~ 12.17日。卵形捕植幼期雖不捕食銀葉粉蝨，但其一生可捕食43.9隻粉蝨一齡若蟲，或16.7隻二齡若蟲。對粉蝨一齡若蟲之每日每雌平均捕食量達2.5隻/日，如添加花粉則捕食3.1隻/日，且較年輕雌每日捕食較多量之粉蝨。卵形捕植後若及雌對銀葉粉蝨之捕食能力，受粉蝨卵、一齡、二齡或三齡食餌密度之影響，對食餌密度的功能反應均呈Holling第Ⅱ型之捕食反應模式；粉蝨一齡若蟲密度為28隻/4 cm2時，雌捕植每日捕食量達其捕食高原，每日（24小時）之最大捕食量為5.88隻/雌 （a: 0.6286；Th: 0.1723）。雌的產卵量隨二齡銀葉粉蝨若蟲密度之增加呈Holling第Ⅱ型之關係，但與一齡粉蝨若蟲密度則呈現Holling第Ⅲ型之反應，當粉蝨密度達24 ~ 32隻/4 cm2時，卵形捕植每日每雌產卵量達最高（1.0 ~ 1.5卵/雌/日）。總之，卵形捕植之發育時間、產卵前期、產卵期、雌壽命、雌生殖力、子代性比、族群增殖介量及對銀葉粉蝨供飼密度之功能反應與數量反應，受不同食餌齡期顯著影響。卵形捕植偏好捕食銀葉粉蝨之一齡及二齡若蟲，並為較適宜的食餌源，添加花粉則減少捕植的死亡率及逃跑率，提高生殖力及壽命，進而提高族群的增殖率，但粉蝨卵則否。銀葉粉蝨成蟲和卵分布於胡瓜上位葉，一、二齡若蟲出現於中位葉，三、四齡若蟲則位於下位葉。卵形捕植密度顯著以胡瓜中位葉為最高，與其捕食粉蝨之一、二若蟲及粉蝨在株內分佈有關。銀葉粉蝨族群於胡瓜上屬於聚集分布型（a = 0.401、b = 1.257。α= 1.325、β= 1.090），而卵形捕植亦傾向聚集分布型（a = 0.311、b = 1.074。α= 1.477、β= 1.014）。秋季至翌年春季（10月 ~ 5月），卵形捕植及銀葉粉蝨族群密度受溫度影響呈正相關關係，但二者之夏季族群則未受溫度影響。週降雨量對捕植及粉蝨族群密度則無影響。卵形捕植密度（Y）受銀葉粉蝨密度（X）反應呈直線迴歸之關係（Y = 0.4458x + 0.4123；R2 = 0.7740；p<0.0001），二者族群密度於胡瓜上呈同律性波動，即卵形捕植為銀葉粉蝨之密度依變因子。卵形捕植族群於溫室胡瓜上獲致良好增長，網室內釋放卵形捕植對銀葉粉蝨密度之抑制效果與化學防治相同；且天敵釋放區的胡瓜產量為未釋放區的1.74倍。卵形捕植與銀葉粉蝨在胡瓜上之相互關係顯著，接種釋放卵形捕植可顯著降低銀葉粉蝨族群密度及確保胡瓜產量，建議銀葉粉蝨初遷至胡瓜植株，或粉蝨成蟲密度達10隻/株時，即釋放卵形捕植成（7隻/株或14隻/株），可獲致較佳的抑制銀葉粉蝨之效果。若謹慎選擇施用化學殺蟲及殺菌劑，將可建立完整的銀葉粉蝨綜合管理模式。
Both male and female silverleaf whitefly (SLWF), Bemisia argentifolii Bellows and Perring, feeding on cucumber, matured in 19.7 ~ 19.9 days at 28 ℃. Adult females laid 101 eggs in 25.6 days of oviposition period with a rate of 3.64 eggs per female per day. Peak reproduction rate was found at either day 4 (6.52 eggs/female/day) or day 8 females (6.02 eggs/female/day). SLWF population multiplied 101.5 times in a mean generation time of 29.6 days with 0.156 eggs/female/day of intrinsic rate of increase. The strategies successes used by SLWF for host adaptation, if not on all kinds of hosts but at least in cucumbers, are maturity rate and adult longevity instead of reproduction rate. Feeding on cucumber pollen, 68.8% Amblyseius ovalis (Evans) females developed into adults, but none on honey-dew of silverleaf whitefly (Bemisia argentifolii, SLWF). Females of A. ovalis deposit most of their eggs on the top of chaeta of underside of leaves with 26.8 eggs per female in an average of a 24.4 day life span. The daily reproduction rate per female is 1.1 eggs. Two highest daily reproduction rates (2.0 ~ 2.1 eggs/female/day) of females were found at female aged 4 and 8 ~ 10 days; the female sex ratio (female/ (female + male)) of offspring was 0.68. A total of 16.7% females feeding on cucumber pollen did not reproduce eggs, but the females resumed egg reproduction when first instars of SLWF were supplied. A. ovalis feeding on eggs, 1st and 2nd instar of silverleaf whitefly, Bemisia argentifolii has shorter developmental duration, better survival rate, and longer longevity. All the predator females reproduced eggs when they fed on the 1st or 2nd insatr of SLWF, but only 50.0 % did on SLWF eggs and 61.1 % did on eggs and pollen. Feeding on 2nd instar of SLWF with pollen, A. ovalis females gave the highest fecundity, while A. ovalis feeding on eggs with pollen added gave the lowest one. The daily reproduction rates (0.1 ~ 1.3 eggs/♀♀/day) of A. ovalis were significantly varied due to stages of SLWF preys. The net reproductive rate (Ro) of 4.28 ~ 21.86 and the intrinsic rate of increase (rm) of 0.140 ~ 0.288 and generation time (T) of 10.41 ~ 12.17 days were found while A. ovalis fed on tested stages of SLWF. The larvae of predator didn't prey on SLWF, but other stages (protonymph, deutonymph and female) foraged an average of 43.9 first instar or 16.7 second instar of SLWF in the life-time of A. ovalis. Deutonymphs and females of A. ovalis showed a Holling typeⅡfunction when it fed on eggs and immature stages of SLWF. Female of A. ovalis retained the highest daily predation rate (predation plateau) 5.88 nymphs in 4 cm2 leaf disc at prey density of 28 1st instar nymphs in 24 hours (a: 0.6286, Th: 0.1723). A. ovalis female showed highest daily reproduction rate of 1.0 ~ 1.5 eggs/female/day when offered 24 ~ 32 nymphs in 4 cm2 leaf disc. Consequently, the stage-specific effects of SLWF were found and evaluated from the response of developmental duration, pre-oviposition period, oviposition period, longevity, fecundity, sex ratio of progeny, and intrinsic rate of increase of A. ovalis. The variations on functional and numerical responses of A. ovalis were also correlated to the different B. argentifolii stages. Feeding on SLWF, A. ovalis completed its maturity with high survival rate and reproductive rate. Furthermore, the development rate, longevity and fecundity of A. ovalis were enhanced when the additional cucumber pollen was added. We conclude that A. ovalis prefers SLWF 1st and 2nd instars later instead of eggs; therefore, SLWF 1st and 2nd instars are suitable food for population growth of A. ovalis. The vertical distribution of Bemisia argentifolii was stage-specific by eggs, nymphs and adults on cucumber. Adults and eggs appeared at upper leaves, while the 1st & 2nd instar nymphs and 3rd & 4th instar nymphs appeared at middle and lower leaves, respectively. A high density of active stages of Amblyseius ovalis was attracted by the 1st and 2nd nymphs of whitefly which aggregated on the middle leaves. The spatial distribution patterns of B. argentifolii and A. ovalis were aggregated according to Taylor's Power Law (a: 0.401, b: 1.257 and a: 0.311, b: 1.074) and Iwao's Mean Crowding Regression (α: 1.325, β: 1.090 andα: 1.477, β: 1.014). Population densities of both predacious mite and whitefly did not depend on temperature in summer season (Jun. ~ Sep.) but did in the period of October to May. A. ovalis or B. argentifolii did not positively correlate with weekly precipitation. Population density increases of A. ovalis and B. agrentifolii on cucumber appeared highly synchronized (Y = 0.4458x + 0.4123, R2 = 0.7740, p < 0.0001). Apparently, the A. ovalis was an important density dependent factor of B. argentifolii on cucumber. A. ovalis showed same degree of effectiveness as chemical measures did to suppress SLWF population increases on cucumbers. The cucumber yield was 1.74 times on A. ovalis released plots than the no predator released plots. In order to gain a better suppression on SLWF density and a higher yield of cucumber fruitage, we released A. ovalis of 7 adults/plant or 14 adults/plant. Inoculative release of A. ovalis in cucumber field could increase the cucumber yield at the lower population density of SLWF. We suggest that A. ovalis can be adopted for integrated control of SLWF with carefully selected pesticides.
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