烟粉虱对不同寄主植物的选择性和适应性测试

为了明确在田间烟粉虱Bemisia tabaci(Gennadius)对不同寄主植物选择性和适应性,本实验在室内用Y型嗅觉仪测定了烟粉虱对13种寄主植物的选择性,随后对田间随机排列种植的这13种寄主植物依照测试结果由强到弱依次拔除(拔除次序为茄子、番茄、黄瓜、辣椒、棉花、茼麻、西葫芦、油菜、花菜、小青菜、莲花白、胡萝卜和苦瓜),每次拔除间隔时间为5 d,结果显示:田间第一次调查的结果与室内选择性测试结果一致;随着最适宜寄主的拔除,烟粉虱成虫数量在与其引诱力相近的一种或几种寄主上的略有增加,而其它植物上却没有大的变化,这表明随着最适宜寄主的拔除,烟粉虱成虫会重新分布,但趋向分布于引诱力相对较强的寄主植物;随着寄主植物的拔除,烟粉虱卵、若虫和蛹在引诱力较强的植株上均有所增加;但西葫芦拔除之后其余植株上烟粉虱卵、若虫和蛹的数量没有明显变化;小青菜拔除后,其余植株上烟粉虱卵、若虫和蛹的数量又有所增加。这表明随着最佳寄主的拔除,烟粉虱会趋向选择于引诱力相对较强的寄主植物产卵,当烟粉虱从嗜好性强的植物转移到嗜好性弱的植物时,产卵适应会滞后于取食适应。但整个实验过程中苦瓜上的烟粉虱上成虫、卵、若虫和蛹的数量均变化不大,苦瓜上的成虫应属偶然分布其上,烟粉虱成虫并不取食苦瓜,苦瓜对烟粉虱有趋避作用。本实验模拟田间种植模式,因此实验结果对田间种植具有指导意义。     

烟粉虱成虫对黄瓜叶龄的喜好性及与后代发育适合度间的关系

在室内采用笼罩和发育测定方法,研究了烟粉虱成虫对黄瓜叶龄的喜好性及其与后代生长发育、存活之间的关系,同时调查了叶毛密度与成虫喜好性之间的相关关系。结果表明(1)烟粉虱成虫比较喜欢在黄瓜植株的中部叶片取食和产卵。(2)叶龄对烟粉虱的存活率没有显著影响,对烟粉虱的发育历期只在卵期和若虫四龄期表现出显著影响,对其他龄期或整个世代均没有显著影响。(3)叶毛密度随着叶龄的增大而顺次显著减小;在接虫初始阶段,烟粉虱成虫的叶片选择性与叶毛密度成显著负相关关系,但72h后具有中等叶毛密度的叶片上的成虫数量和着卵量均显著高于叶毛密度较大或较小的叶片。研究结果对培育抗烟粉虱的黄瓜品种和改进烟粉虱的防治措施具有一定指导意义。     

寄主植物对B型烟粉虱形态学和生物学特性的影响

为了解B型烟粉虱(Bemisiatabaci)在不同寄主植物上的生物学特性,以制定科学的综合治理措施,作者在271℃的条件下,研究测定了B型烟粉虱在棉花(Gossypiumhirsutum)、一品红(Euphorbiapulcherrima)、甘蓝(Brassicaoleraceavar.capitata)、黄瓜(Cucumissativus)、西葫芦(Cucurbitapepo)、茄子(Solanummelongena)和番茄(Lycopersiconesculentum)上各虫态大小、成活率、发育历期、成虫寿命、平均产卵量等生物学参数。结果表明:取食不同寄主植物的烟粉虱伪蛹在黄瓜和棉花上体型最大,在一品红上最小;烟粉虱从卵到成虫羽化,发育历期以在一品红上最长(22.0d),黄瓜上最短(17.3d);平均单雌产卵量以在番茄上最多(266.5粒/雌),一品红上最少(112.9粒/雌);成虫的寿命在番茄、黄瓜和茄子上显著长于在其他4种寄主植物上。烟粉虱从卵发育到成虫的存活率以在黄瓜上最高(77.8%),西葫芦上最低(55.6%),两者差异显著。综合比较7种寄主植物,黄瓜是烟粉虱种群生长发育和繁殖的最适寄主。     

供氮水平对番茄苗期Q型烟粉虱成虫种群动态的影响

烟粉虱(Bemisia tabaci)是重要的农业害虫。在栽培管理中,为了减少化学农药的施用,对该害虫采取生态防控措施日益得到重视。以Q型烟粉虱为研究对象,根据温室大棚内9次烟粉虱成虫种群数量调查和番茄苗期5项农艺指标测量,结合主成分分析、线性逐步回归分析及Pearson相关性分析,从"氮素-番茄-Q型烟粉虱"互作角度开展生态防控措施研究,旨在探明番茄苗期的烟粉虱成虫种群发生数量与氮素水平关系。结果表明:3个氮水平(高氮1134 mg·L^-1,标准氮945 mg·L^-1,低氮756 mg·L^-1)下的5个番茄指标(株高、茎粗、叶面积、叶绿素相对含量、叶片全氮含量)最大值基本呈现高氮>标准氮>低氮的规律;调查的9次烟粉虱虫口数量在最大峰值时的高低排序为高氮>标准氮>低氮。主成分分析表明,3种氮素水平下叶绿素相对含量是影响烟粉虱成虫虫口数量的主要因子。线性回归与相关性分析表明,3种氮素水平下的叶片全氮含量、叶绿素相对含量与虫口种群数量相关性较高。氮营养是影响植物和烟粉虱的关键因素之一,高氮水平下番茄长势较好,Q型烟粉虱虫口数量居多;作物叶片全氮含量和叶绿素相对含量可作为检测Q型烟粉虱种群发生消长的生态防控指标。     

烟粉虱成虫在日光温室内的分布和日活动规律

采用中色粘虫板(黄板)和植株调查方法在河北省固安县日光温室内研究了烟粉虱成虫在黄瓜结瓜盛期(4月下旬~5月上旬)的分布和日活动规律。结果表明,温室北边平均诱集量((668·8±663·9)头/(板·d))是南边((357·5±349·4)头/(板·d))的1·87倍;除8∶00~10∶00以外,其他时段内北边诱集量均显著高于南边;同时,北边植株上烟粉虱成虫数量也显著高于南边。温室东边逐日和各时段诱集量均高于西边,但差异不显著。在垂直方向,烟粉虱成虫在黄瓜所有叶片上均有分布。烟粉虱成虫从6∶00~18∶00各时段均很活跃,但不同时段活动水平存在差异。8∶00~10∶00平均诱集比例最高(25·7%±9·7%),12∶00~14∶00最低(13·2%±5·2%);8∶00~10∶00的诱集量显著高于其他时段。另外,黄板南面诱集量((352·5±186·1)头/(板·d))显著高于北面诱集量((160·7±90·4)头/(板·d))。对日光温室黄瓜上烟粉虱的监测、成虫诱杀和综合治理的意义进行了讨论。     

不同作物田烟粉虱发生的时空动态

2008～2009年连续2年系统调查了番茄、茄子、棉花、大豆、玉米等寄主植物上烟粉虱种群发生的时间与空间动态。结果表明：不同寄主植物上的烟粉虱成虫及其伪蛹数量有显著性差异,其密度大小依次为：茄子>棉花>番茄>大豆>玉米。其中,在玉米上除了发现极少量的成虫逗留外,没有发现烟粉虱的卵及若虫。在发生的时间序列上,烟粉虱成虫及伪蛹的数量呈现为先逐渐上升后又下降的变化过程,发生高峰期集中在8月5日到8月31日,9月初以后烟粉虱数量慢慢减少。在空间分布上,表现为烟粉虱成虫喜食寄主的上部叶片。统计分析显示,寄主对烟粉虱成虫和伪蛹的数量的影响极显著,而年份对其数量的影响没有显著差异。由此得出的烟粉虱发生和达到高峰的时间,可为烟粉虱预测预报和区域性综合治理提供重要理论依据。     

下调烟粉虱MED隐种BtabCSP6表达对番茄黄化曲叶病毒传播的影响

【目的】番茄黄化曲叶病毒(tomato yellow leaf curl virus, TYLCV)是对农业生产造成威胁的主要病毒之一,自然条件下通过媒介昆虫烟粉虱Bemisia tabaci传播。已有研究表明烟粉虱雌成虫比雄成虫具有更强的获毒与传毒能力。本研究旨在探明烟粉虱化学感受蛋白(chemosensory protein, CSP)基因BtabCSP6表达对病毒传播的影响,为控制病毒发生寻找新途径。【方法】使用TYLCV侵染性克隆方法获得带毒番茄植株,微虫笼收集不带毒烟粉虱MED隐种成虫固定在感染TYLCV的番茄植株叶片获毒48 h;利用RT-qPCR技术测定分别取食感染和未感染TYLCV番茄植株的烟粉虱MED隐种雌雄成虫体内BtabCSP1-8基因表达量变化;通过饲喂法利用RNAi对烟粉虱MED隐种雌成虫BtabCSP6基因进行干扰48 h后饲喂TYLCV感染的番茄植株,测定烟粉虱MED隐种雌成虫的获毒率和传毒率。【结果】RT-qPCR检测结果表明,与未侵染的烟粉虱MED隐种雌成虫相比,侵染TYLCV的雌成虫体内BtabCSP3和BtabCSP6基因的表达量变化最为显著。同样地,在侵染TYLCV的雄成虫体内,BtabCSP4和BtabCSP6表达量的变化最为明显。饲喂dsBtabCSP6 48 h后,烟粉虱MED隐种雌成虫体内BtabCSP6表达量降低;取食感染TYLCV番茄植株不同时间烟粉虱MED隐种雌成虫的获毒率和不同数量雌成虫对未感染TYLCV的番茄植株的传毒率与对照相比均显著降低。【结论】下调烟粉虱MED隐种雌成虫体内BtabCSP6基因的表达,可显著降低烟粉虱MED隐种雌成虫的获毒率和传毒率,说明BtabCSP6可能影响TYLCV传播。     

辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响

在实验室条件下研究了辣椒碱对烟粉虱的生物活性及生长发育和生殖力的影响.结果表明:辣椒碱对烟粉虱各虫态均有杀虫活性,且随辣椒碱浓度的增大活性增强;辣椒碱浸叶法/浸虫法处理对烟粉虱成虫、卵和若虫的毒力(LC50分别为3525.79、1603.29和1526.27mg·L-1))均高于内吸法处理(LC50分别为5360.04、2359.19和5897.43 mg.L-1),两种处理方法下辣椒碱对烟粉虱卵的毒力均明显高于对成虫的毒力;2000和4000 mg·L-1浓度辣椒碱对烟粉虱成虫具有明显的拒食作用,烟粉虱在该两种浓度辣椒碱处理过的棉花叶上取食24 h的蜜露分泌量均显著低于取食非处理棉花叶后的蜜露分泌量;辣椒碱各试验浓度对烟粉虱成虫均表现出较强的产卵忌避作用,当辣椒碱处理浓度达4000 mg·L-1时,对烟粉虱的选择性产卵忌避率和非选择性产卵忌避率分别高达94.2％和83.0％.500、1000和2000 mg·L-1辣椒碱浸渍处理对烟粉虱存活卵和若虫的发育历期、成虫羽化率均没有影响,但辣椒碱4000mg·L-1处理明显延长烟粉虱若虫发育历期、降低成虫羽化率.不同浓度辣椒碱处理均明显抑制烟粉虱生殖力,且这种抑制作用随辣椒碱浓度的增大而增强.     

棉株上烟粉虱若虫种群的垂直分布与统计方法研究

对烟粉虱Bemisiatabaci在棉花植株上的垂直分布调查发现 ,烟粉虱在棉株各部位均有分布 ,且分布极不均匀 ,统计分析表明棉株各部位间烟粉虱的种群数量存在显著的差异。棉花顶部烟粉虱的若虫数量约占全棉株若虫总量的 1 6%,通过对棉株各部位烟粉虱的若虫数量与整株若虫总量的回归分析 ,建立了相应的回归方程式     

烟粉虱若虫在甘蓝和花椰菜莲座期不同叶位层上的分布

对烟粉虱Bemisia tabaci(Gennadius)若虫在花椰菜Brassica oleraceavar.italica和甘蓝Brassica oleraceavar.capitata不同叶位层的分布调查结果显示,烟粉虱若虫在菜株各部位均有分布,但各部位间极不均匀。统计分析表明:其若虫的种群数量在同种蔬菜的菜株各部位间均存在极显著的差异。但在2种叶菜寄主间同一部位上烟粉虱若虫的种群数量差异不明显。通过对菜株各部位烟粉虱若虫量与整株总量的回归分析,建立了叶菜植株不同部位烟粉虱虫量与全株总虫量的回归方程及多元回归模型。     

Within-plant distribution of Bemisia tabaci (Homoptera: Aleyrodidae) adults and immatures on greenhouse-grown winter cucumber plants

Within-plant distribution of adults, pupae, nymphs, and eggs of Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae) on leaves of greenhouse-grown winter cucumber, Cucumis sativum L., plants were studied in field plots for integrated pest management decision making. Distribution of specific life stages depended on the leaf positions. The leaves with most abundance and low or lowest variation of whiteflies were leaves 8-12 for adults, 8-11 for pupae, 6-12 for nymphs, and 6-9 for eggs. In light of the criterion in selecting within-plant sample sites with pest abundance and low variation, these leaves were considered as the most convenient for sampling specific life stages of B. tabaci. Single a and b values for each life stage of the whitefly were calculated by Taylor's power law and were used to estimate minimum sample sizes at a precision of 0.25 (SE/mean). The minimum sample size decreased with increasing density of adults on leaves 8-12, of nymphs on leaves 7 and 8, and of eggs on leaf 6, but slightly increased with increasing density of pupae on leaves 8-11, of nymphs on leaves 6 and 9-12, and of eggs on leaves 7-9.     

The contribution of tomato and alternative host plants to tomato leaf curl virus inoculum pressure in different areas of South India

Indian tomato leaf curl virus (ToLCV) (Geminiviridae: Sub-group III) was detected both in field-collected and laboratory-reared B. tabaci using a triple-antibody sandwich enzyme-linked immunosorbent assay (TAS-ELISA). ToLCV was detected in six of the 10 group samples of field collected B. tabaci. ToLCV was also identified in 13 weed species commonly found in Karnataka, both by symptom expression and TAS-ELISA. ToLCV from c. 61% of infected plants was transmitted successfully to tomato by B. tabaci. Tomato plots were planted at three locations on the University of Agricultural Sciences Campus, Bangalore. Indian tomato leaf curl virus disease (ToLCVD) incidence increased most rapidly when the tomato plot was situated adjacent to an older ToLCVD-infected tomato field. When the plots were positioned in a dryland or a wetland area, at least 500 m away from any infected tomato fields, the ToLCVD incidence increased less rapidly, although in all sites it was 100% by 11 wk after transplanting. The numbers of B. tabaci caught on yellow traps in all sites increased during weeks 1–3 after transplanting and thereafter remained at between 10–15 adults trap^-1 24 h^_1. Adult numbers recorded on tomato plants by direct counts remained approximately constant at 2–4 adults plant“”¹. Tomato fields were planted in three taluks (administrative areas) of Karnataka, that had different current and previous histories of tomato production. ToLCVD incidence increased most and least rapidly, respectively, in Kolar taluk where tomato is grown continuously and Doddaballapur tuluk where tomato was grown in the area for the first time. In Malur tuluk, where tomato was grown discontinuously (once a year), the incidence of ToLCVD increased at an intermediate rate. Weed host-plant species growing near the experimental sites had averages of between 1.5–10.0 B. tabaci nymphs per plant, whereas the tomato plants had only 0.3 nymphs per plant. The percentage parasitism of B. tabaci nymphs on tomato and weed species, respectively, was 0.7% and 2–6%. Nymphs and pupae were parasitised by an Encarsia sp. and Eretmocerus mundus Mercet. The relevance and implications of these findings for the epidemiology and management of ToLCVD in Karnataka State, South India is discussed.     

Economic injury level and sequential sampling plan for Bemisia tabaci in outdoor tomato

Abstract:  This work aimed to determine the economic injury levels and to establish sequential sampling plans for nymphs and adults of the whitefly Bemisia tabaci Genn. (Sternorrhyncha: Aleyrodidae) in tomato fields. Densities of nymphs and adults, as well as crop yield were evaluated in 13 commercial tomato fields to determine the economic injury levels. The whitefly nymphs were sampled by direct counting in a leaf from the lower part of the canopy and the adults were sampled by beating an apical leaf against a white plastic tray. The sequential sampling plan was based on data collected in eight commercial tomato fields. The validation of the sequential sampling plan was carried out based on the curves of operational characteristics and average sample numbers. The decisions reached with the conventional and the sequential sampling plans in 21 commercial fields were compared for the intended validation of the sequential plan. The economic injury levels were four nymphs per leaf and one adult per tray. The decisions taken based on the sequential sampling plan were similar to those obtained through the conventional sampling plan. Most of the decisions taken with the sequential sampling plan were obtained through the minimum number of seven samples per field for nymphs and 11 samples per field for adults, with reductions of 84.44% and 54.17% in the number of samples required to reach a decision with the sequential sampling plan compared with the conventional sampling plan.     

烟粉虱对四种蔬菜寄主的选择性

为探讨利用趋避作用防治烟粉虱的可能性,进行了3方面试验：1）烟粉虱Bemisia tabaci (Gennadius) 对黄瓜、花椰菜、油菜和莴苣等4种蔬菜的寄主选择性; 2）互喷烟粉虱不同嗜好的寄主植物汁液对其寄主选择性的影响; 3）不同间作方式对黄瓜叶上烟粉虱成虫密度的影响。结果表明,烟粉虱对供试植物有明显的选择性,其嗜好程度为花椰菜>黄瓜>油菜>莴苣。喷施莴苣和花椰菜汁液对烟粉虱的寄主选择性均有显著影响,喷施莴苣原液后,花椰菜和黄瓜上的成虫数分别减少79.6%和87.4%,花椰菜上的着卵量减少84.3%;喷施花椰菜原液后,莴苣上的成虫数和着卵量分别增加82.4%和79.2%,表明不同蔬菜中的内含物是引起烟粉虱对寄主选择性的重要原因。在黄瓜中间作莴苣可使黄瓜叶上烟粉虱成虫数平均减少76.5%;间作花椰菜时,通过诱集作用,也可使黄瓜叶上的成虫数平均降低69.7%。这些结果为利用喷施蔬菜汁液和间作方式控制烟粉虱危害提供了理论依据。     

寄主植物对B型烟粉虱选择行为和生物学参数的影响

通过培养皿内自由扩散观察和生物学观察,对黄瓜、茄子、辣椒、棉花和甘薯上B型烟粉虱的寄主选择性和生物学参数进行了研究.结果表明：B型烟粉虱成虫向寄主植物叶片自由扩散的初始阶段（2 h）,各寄主植物叶片上虫量的差异不大,在随后的4～48 h内黄瓜叶片上的虫量不断增加,茄子、棉花和甘薯叶片上的虫量相对稳定,而辣椒叶片上的虫量却不断下降,说明B型烟粉虱对黄瓜的选择性最强、对辣椒的选择性最弱,且饥饿和吡虫啉预处理均不影响B型烟粉虱的寄主选择性;取食不同寄主植物烟粉虱成虫的蜜露分泌量差异显著,从高到低依次为黄瓜、甘薯、棉花、茄子、辣椒;黄瓜、茄子、甘薯、棉花上烟粉虱成虫的寿命显著长于辣椒,其平均单雌产卵量(分别为224.33粒、182.33粒、191.73粒和172.60粒)也均显著高于辣椒(47.83粒);各寄主植物上烟粉虱卵的孵化率和发育历期差异均不显著;烟粉虱若虫在黄瓜、茄子、甘薯和棉花上的发育历期分别为10.60 d、11.96 d、11.11 d和13.20 d,死亡率分别为5.21%、27.78%、17.24%和37.11%,在辣椒上不能完成正常发育.     

Development, survivorship and reproduction of Eretmocerus sp. nr furuhashii (Hymenoptera: Aphelinidae) parasitizing Bemisia tabaci (Hemiptera: Aleyrodidae) on glabrous and non-glabrous host plants

The developmental, survivorship and reproductive biology of Eretmocerus sp. nr furuhashii Rose & Zolnerowich parasitizing Bemisia tabaci (Gennadius) biotype B on tomato, cucumber, eggplant and collard at 26+/-0.5 degrees C was studied. The mean longevity ranged from 6.5 days on tomato to 8.1 days on collard. The mean lifetime fecundities on tomato, cucumber, eggplant and collard were 35.4, 37.3, 41.4 and 46.4 eggs, whereas the mean lifetime fertility was 20.2, 22.7, 28.3 and 33.6 offspring, respectively. Developmental time was longest on cucumber (17.1 days) and shortest on collard (15.9 days). Survival rates varied significantly across host plants. Sex ratio (female symbol:male symbol) varied from 1.71 to 1.93 across the four hosts. The intrinsic rate of increase (rm) was highest (0.157) on collard and lowest on tomato (0.133). Mean generation time (R0) ranged from 14.7 to 20.9 days. All the data demonstrated that the reproductive success and overall performance of E. sp. nr furuhashii increased as the density of leaf hairs declined. As leaf hairs play a key role in determining efficacy, it is unlikely that effective biological control of B. tabaci using E. sp. nr furuhashii will be achieved on non-glabrous crop varieties.     

Evaluation of Serangium n. sp. (Col., Coccinellidae), a predator of Bemisia tabaci (Hom., Aleyrodidae) on cassava

Abstract  The potential of a new, previously unidentified Serangium species (Col., Coccinellidae) to control the high Bemisia tabaci (Gennadius) (Hom., Aleyrodidae) populations on cassava was evaluated. Field and laboratory studies were carried out to determine the abundance and feeding capacity of this Serangium species feeding on B. tabaci on cassava. Serangium nymphs and adults were most abundant in cassava fields late in the season, rising sharply from 5 months after planting (MAP) to a peak at 7–8 MAP. Pre-imaginal development averaged 21.2 days and was longest in eggs and shortest in the L₁ instar. Mean total prey consumption of immature Serangium increased with the stage of development with the lowest consumption in the L₁ instar and highest in the L₄ instar. Mean daily consumption was lowest on the first day after hatching in the L₁ instar and rose to a peak on the 13th day after hatching in the L₄ instar. Each Serangium larva consumed a mean of over 1000 nymphs during its entire development. These results have demonstrated the potential of this Serangium species to control B. tabaci populations on cassava.