昆虫种群生命表简化记录方法:以烟粉虱数据为例

【目的】使昆虫两性生命表研究能省时省力地记录产卵量,同时维持分析的准确性。【方法】本研究以每日记录产卵量的烟粉虱Bemisia tabaci MED隐种(通常称为Q型)感染与未感染Cardinium的2个品系的原始数据为基础,将产卵量按照每2,4和5 d进行简化记录,以验证这种方法的有效性及其对种群参数的影响,并进行显著性分析。【结果】除成虫产卵前期(adult preoviposition period,APOP)和产卵天数受到影响外,简化记录方法对内禀增长率(intrinsic rate of increase,r)、周限增长率(finite rate of increase,λ)、净增殖率(net reproductive rate,R0)、平均世代周期(mean generation time,T)、成虫前历期、繁殖力、雌雄虫寿命和总产卵前期(total preoviposition period,TPOP)均无显著性影响。【结论】结果说明,这种简化记录方法对生命表的主要参数无显著性影响,可用于生命表研究中以节省时间与劳力,并且减小每天检视可能对成虫造成的影响,有利于两性生命表的广泛应用。     

Effect of Ifchit1 gene of Isaria fumosorosea on mortality,oviposition and oxidase activities of Bemisia tabaci

Isaria fumosorosea is one of important entomopathogenic fungi showed a good potential in controlling Bemisia tabaci. The effects of I. fumosorosea ⊿Ifchit1 mutant (Ifchit1 gene deletion mutant) on the mortality, oviposition, and host immunological response of B. tabaci, on Brassica campestris L. plant, were evaluated under laboratory conditions. The wild-type fungal strain infection significantly increased insect mortality and reduced the oviposition effeciency of B. tabaci, whereas the ⊿Ifchit1 mutant was much less effective, resulting in higher survival and ovipositing of B. tabaci. The activities of four insect enzymes were examined during a time course of fungal infection. Insect phenoloxidase, perioxidase, and catalase activities were decreased in whiteflies treated with the wild type and mutant I. fumosorosea strain at 12–36?h post treatment. However, these enzyme activities increased in fungal-treated whiteflies as compared to controls between 36 and 60?h post-infection, reaching peak values. Superoxide dismutase activity in fungal-treated whiteflies was higher than that in controls during the entire experimental time course examined. The overall enzyme activity profiles in ⊿Ifchit1 mutant-treated whiteflies were significantly different from wild-type strain treatments. Our results showed that loss of the Ifchit1 gene in I. fumosorosea affects whitefly mortality, ovipositioning and various antioxidant enzyme activities, providing new insights into the role of chitinases in I. fumosorosea-insect host–pathogen interactions.     

Microbial control of cotton pests: use of the naturally occurring entomopathogenic fungus Aspergillus sp. (BC 639) in the management of Bemisia tabaci (Genn.) (Hemiptera: Aleyrodidae) and beneficial insects on transgenic cotton crops

The commercial adoption of transgenic Bacillus thuringiensis (Bt) cotton (Bollgard II®) reduced the use of insecticides to control Helicoverpa spp. However, the ineffectiveness of the Bt toxin against sucking pests such as silverleaf whiteflies (Bemisia tabaci) resulted in a marked increase in B. tabaci populations and in the use of insecticides to control this pest. The effect of the entomopathogenic fungus Aspergillus sp. BC 639 on B. tabaci and beneficial insects (predominantly predatory insects) was studied in commercial cotton field trials. The results showed that oil-based extracts of the entomopathogenic fungus BC 639 control the number of B. tabaci adults and nymphs in commercial transgenic cotton crops. The BC 639 fungus caused 60.0%, 67.2%, and 68.8% mortality in adults, and 54.6%, 62.3%, and 51.7% in nymphs at 7, 14, and 21 days after treatment, respectively, relative to the unsprayed controls. The effect of BC 639 at concentrations of 125, 250, and 500?ml/ha on low-density B. tabaci (～10 nymphs/leaf) did not differ significantly from that of the commercial insecticide (pyriproxifen). However, at higher densities (>50 nymphs per leaf), low concentrations of BC 639 (125 and 250?ml/ha) were not as effective as 500?ml/ha BC 639 in successfully controlling the pest. A simple graphic analysis suggested that the more B. tabaci nymphs per leaf, the fewer adults per leaf, and that once the number of nymphs increased to ～70 per leaf, a negative feedback regulatory effect reduced the survivorship of the nymphs and adults and/or caused the emigration of the adults from the contaminated leaves in search of new resources. Therefore, the ability of BC 639 to control B. tabaci adults and nymphs with minimal effects on predatory insects indicates its potential utility in supplementing integrated pest management programmes for cotton crops.     

Effects of single and dual species herbivory on the behavioral responses of three thrips species to cotton seedlings

This study investigated the olfactory responses of 3 thrips species [Frankliniella schultzei Trybom, F. occidentalis Pergrande and Thrips tabaci Lindeman (Thysanoptera: Thripidae)] to cotton seedlings [Gossypium hirsutum L. (Malvales: Malvaceae)] simultaneously damaged by different combinations of herbivores. Cotton seedlings were damaged by foliar feeding Tetranychus urticae Koch (Trombidiforms: Tetranychidae), Helicoverpa armigera Hübner (Lepidoptera: Noctuidae), Aphis gossypii Glover (Hemiptera: Aphididae) or root feeding Tenebrio molitor L. (Coleoptera: Tenebrionidae). Thrips responses to plants simultaneously damaged by 2 species of herbivore were additive and equivalent to the sum of the responses of thrips to plants damaged by single herbivore species feeding alone. For example, F. occidentalis was attracted to T. urticae damaged plants but more attracted to undamaged plants than to plants damaged by H. armigera. Plants simultaneously damaged by low densities of T. urticae and H. armigera repelled F. occidentalis but as T. urticae density increased relative to H. armigera density, F. occidentalis attraction to coinfested plants increased proportionally. Thrips tabaci did not discriminate between undamaged plants and plants damaged by H. armigera but were attracted to plants damaged by T. urticae alone or simultaneously damaged by T. urticae and H. armigera. Olfactometer assays showed that simultaneous feeding by 2 herbivores on a plant can affect predator–prey interactions. Attraction of F. occidentalis to plants damaged by its T. urticae prey was reduced when the plant was simultaneously damaged by H. armigera, T. molitor, or A. gossypii and F. schultzei was more attracted to plants simultaneously damaged by T. urticae and H. armigera than to plants damaged by T. urticae alone. We conclude that plant responses to feeding by 1 species of herbivore are affected by responses to feeding by other herbivores. These plant‐mediated interactions between herbivore complexes affect the behavioral responses of thrips which vary between species and are highly context dependent.     

双斑恩蚜小蜂形态学特征、生活习性及其寄生行为

双斑恩蚜小蜂EncarsiabimaculataHeratyetPolaszek是烟粉虱Bemisiatabaci(Gennadius)的主要寄生性天敌之一。作者对双斑恩蚜小蜂的形态特征进行了描述。在实验室条件下,对双斑恩蚜小蜂的生活习性、寄生行为进行了观察。双斑恩蚜小蜂成蜂26℃时平均寿命约为7d,每雌产卵量273粒,雌蜂比例占据绝对优势,雌雄性比约为8∶1。双斑恩蚜小蜂的寄生过程大致分为寄主定位、寄主检查、穿刺、产卵、清扫、梳理和休憩等几个阶段。     

球孢白僵菌对四种十字花科蔬菜害虫的兼控潜力评价

研究了分离自小猿叶甲的一株球孢白僵菌(Beauveria bassiana(SCAU-BB01D))对十字花科蔬菜4种非目标害虫烟粉虱Bemisia tabaci、小菜蛾Plutella xylostella、黄曲条跳甲Phyllotreta striolata和菜缢管蚜Lipaphis erysimi的致病能力。结果表明,在实验室条件下,该菌株对以上4种害虫均有不同程度的侵染力。1×108孢子/mL的白僵菌悬浮液对1,2,3,4龄烟粉虱若虫的侵染率分别为84.88,86.81,55.94和38.78%;对小菜蛾2,3和4龄幼虫的侵染率为67,59和44%;对黄曲条跳甲幼虫和成虫分别为63%和60%;对菜缢管蚜成蚜和若蚜的侵染率分别为44%和35%。通过机率值分析,得出该菌株对烟粉虱1~4龄若虫的LT50分别为4.14,3.78,6.24和7.59 d;对小菜蛾2~4龄幼虫的LT50分别为7.29,8.16和9.82d;对黄曲条跳甲成虫和幼虫的LT50分别为11.22和8.11 d;对菜缢管蚜成蚜和若蚜的LT50分别为11.01和12.15 d。说明该球孢白僵菌菌株对烟粉虱、小菜蛾和黄曲条跳甲3种非目标害虫具有一定的兼控作用,在蔬菜害虫的生物防治中具一定的应用潜力。     

重大外来害虫B型烟粉虱的入侵行为和生态机制

烟粉虱Bemisia tabaci(Gennadius)复合种是热带、亚热带及相邻温带地区的主要害虫之一。其中的B型烟粉虱在近20年来随观赏植物的运输在世界范围内广泛传播扩散,并在许多入侵地迅速取代本地的土著烟粉虱,通过直接取食植物汁液、传播植物双生病毒等方式对当地的农业生产造成极大危害。在B型烟粉虱入侵生物学研究方面,作者课题组研究发现,至少有两个主要机制导致或促进了B型烟粉虱的广泛入侵及其所伴随的双生病毒流行:(1)入侵烟粉虱与土著烟粉虱之间的"非对称交配互作";(2)入侵烟粉虱与所传双生病毒之间的间接互惠共生关系。这些研究结果从一定程度上揭示了B型烟粉虱成功入侵的行为和生态机制,并为进一步探讨烟粉虱的入侵机制提供了思路。     

一种快速鉴别烟粉虱与温室白粉虱成虫的方法——复眼镜检法

介绍能够快速鉴别2种形态相似的重要农业害虫即烟粉虱Bemisia tabaci(Gennadius)和温室白粉虱Trialeurodes vaporariorum(Westwood)成虫的方法——复眼镜检法及其应用。复眼镜检法研究表明,烟粉虱成虫上部复眼、下部复眼之间有一个小眼连接,而温室白粉虱成虫上部复眼、下部复眼是完全分离的。     

蚜小蜂和粉虱座壳孢对烟粉虱的控制作用研究

研究了烟粉虱两种寄生性天敌桨角蚜小蜂(Eretmocerus sp．)和粉虱座壳孢(Aschersonia aley-rodis)单独使用和联合使用时对烟粉虱种群的控制作用。结果表明,在单独进行控制时,在一个世代内按5×10^6个孢子·ml^-1喷施粉虱座壳孢2次,对烟粉虱种群的控制作用达95．74％,按每株植株3头雌蜂的密度释放桨角蚜小蜂2次,对烟粉虱种群的控制作用达57.58％。在两者联合控制时,一个世代内喷施粉虱座壳孢2次,再释放桨角蚜小蜂1次或2次,对烟粉虱种群的控制作用达97．02％～97．91％,烟粉虱种群增长趋势指数低于1,种群数量逐渐下降,联合使用时,桨角蚜小蜂和粉虱座壳孢间无消极影响。     

黄板对菜地烟粉虱的诱集作用研究

应用黄板诱集花菜和菜豆田中烟粉虱成虫。结果表明：花菜田中东西向放置的黄板诱集效果优于南北向,搭架的菜豆田中顺行向优于垂直行向;黄板放置高度花菜田以黄板下端略高于菜叶顶部为宜,搭架的菜豆田以架中部为宜;诱集时间以11时至15时为佳。