Aerial electrostatic‐charged sprays for deposition and efficacy against sweet potato whitefly (Bemisia tabaci) on cotton

Background: The efficacy of aerial electrostatic‐charged sprays was evaluated for spray deposit characteristics and season‐long control of sweet potato whitefly (SWF), Bemisia tabaci Genn. biotype B (aka B. argentifolii Bellows & Perring), in an irrigated 24 ha cotton field. Treatments included electrostatic‐charged sprays at full and half active ingredient (AI) label rate, uncharged sprays and conventional sprays applied with CP nozzles at full label rate with several different insecticides. Results: Spray droplet size was significantly smaller for electrostatic‐charged sprays than for conventional sprays in top‐ and mid‐canopy locations. The seasonal mean numbers of viable eggs and live large nymphs on cotton treated with electrostatic‐charged sprays were comparable with those on cotton treated with conventional applications. Lethal concentration (LC₅₀) for adults for electrostatic‐charged sprays was comparable with that for conventional sprays. Conclusion: The amenability of electrostatic‐charged sprays to a wide array of pesticides with different chemistries should be a useful tool in combating insect resistance. Results reported here suggest that the potential exists for obtaining increased efficacy against whiteflies using an electrostatic spray charging system, and that additional research will be required to improve charge‐to‐mass (Q/M) ratio in order to increase deposition of pest control materials to the lower surfaces of cotton leaves where the whiteflies reside. Copyright © 2009 Society of Chemical Industry     

Complementary effect of Phloxine B on the insecticidal efficacy of Isaria fumosorosea SFP‐198 wettable powder against greenhouse whitefly,Trialeurodes vaporariorum West.

BACKGROUND: Insecticidal activities of five photoactive dyes against greenhouse whitefly (GWF), Trialeurodes vaporariorum West., in tomatoes were investigated to improve the control efficacy of an entomopathogenic fungal product, Isaria fumosorosea SFP‐198 wettable powder (WP). Azorubine, Eosin B, Erythrosine, Brilliant Green and Phloxine B were used in this work, accompanying pyriproxyfen emulsifiable concentrate (EC) as a commercial standard for comparison. RESULTS: Phloxine B had the highest control efficacy in glasshouse conditions. The most suitable dose of Phloxine B was determined as 0.005 g L^?1, given the dosage‐dependent control efficacy and phytotoxicity of the dye, and its influence on the germination of SFP‐198 conidia. In field conditions, SFP‐198 WP + Phloxine B (2 + 0.005 g L^?1; tank mix) showed 89.1 and 95.3% control efficacy 7 and 14 days post‐application, which was significantly higher than the efficacy of SFP‐198 WP alone (43.5 and 64.0%), Phloxine B (47.5 and 30.7%) or pyriproxyfen EC (67.7 and 80.2%). CONCLUSION: Phloxine B cooperates with SFP‐198 WP complementarily, possibly in the order of killing action (early: Phloxine B; late: SFP‐198 WP). The dye can be incorporated into SFP‐198 WP to improve its efficacy and applied to other Hypocrelean entomopathogenic fungal products. Copyright © 2010 Society of Chemical Industry     

Toxicity and growth-suppression exerted by diafenthiuron in the sweetpotato whitefly,Bemisia tabaci

Diafenthiuron (CGA 106 ’630), a thiourea, was sprayed prior to a 48-h infestation by adult females of the sweetpotato whiteflyBemisia tabaci Gennadius, on cotton seedlings under greenhouse conditions; it subsequently suppressed strongly progeny formation of the whitefly, resulting in approximately 50% progeny formation relative to control at 5 mg a.i./l. When the different development stages were separately sprayed directly, the larval stage was the most susceptible, resulting in 50% and 90% mortality of 2nd instars at concentrations of 6.5 and 49.2 mg a.i./l, whereas the LC50 values of adults and pupae were 23 and 45 mg a.i./l, respectively. A mild (30–35%) reduction of egg hatch was obtained at a range of 5–125 mg a.i./l. Thus the potency of diafenthiuron against various stages was in the order larvae > adults > pupae > eggs. Diafenthiuron exhibited a low vapor phase toxicity and had no translaminar effect when tested on first instars ofB. tabaci. The high potency of diafenthiuron against whiteflies described herein, against aphids and mites, as stated in the literature, and against some lepidopterous pests, render this compound an important insect control agent for pests of cotton and other crops.     

The role of B‐type esterases in conferring insecticide resistance in the tobacco whitefly,Bemisia tabaci (Genn)

Separation of non‐specific esterases on electrophoretic gels has played a key role in distinguishing between races or biotypes of the tobacco whitefly, Bemisia tabaci. One intensively staining esterase in particular (termed E_0.14) has assumed significance as a diagnostic of B‐type whiteflies (aka Bemisia argentifolii), despite any knowledge of its biological function. In this study, a whitefly strain (B‐Null) homozygous for a null allele at the E_0.14 locus that had been isolated from a B‐type population was used to demonstrate a significant role for E_0.14 in resistance of B‐type populations to pyrethroids but not to organophosphates (OPs). Bioassays with pyrethroids, following pre‐treatment with sub‐lethal doses of the OP profenofos (to inhibit esterase activity), coupled with metabolism studies with radiolabelled permethrin, supported the conclusion that pyrethroid resistance in a range of B‐type strains expressing E_0.14 was primarily due to increased ester hydrolysis. In the same strains, OP resistance appeared to be predominantly conferred by a modification to the target‐site enzyme acetylcholinesterase. © 2000 Society of Chemical Industry     

防治斜纹夜蛾蛹和2龄幼虫的棒束孢菌株筛选

为获取对斜纹夜蛾Spodoptera litura(Fabricius)具致病力的生防真菌资源,通过对8株寄主为鳞翅目蛹的棒束孢属Isaria spp.真菌进行形态学和分子系统学鉴定;以斜纹夜蛾的蛹和2龄幼虫为试虫,分别采用拌土法和浸渍法测试菌株的致病力。结果显示:菌株GZUIFR08XS1、GZUIFR04XS8、GZUIFR08XS13为环链棒束孢I.cateinannulata,菌株GZUIFR08LYS4、GZUIFR04XS5、GZUIFR04XS7、GZUIFR08XS12、GZUIFR04XS16为粉棒束孢I.farinose。8株菌对斜纹夜蛾的蛹和2龄幼虫均有致病力。土壤接种5 mL浓度为2×10~8个/mL的分生孢子,环链棒束孢GZUIFR08XS1、GZUIFR04XS8对蛹的致死率均为100%。接种浓度为1×10~8个/mL的分生孢子,环链棒束孢GZUIFR04XS8对2龄幼虫致死率为(78.21±2.22)%,较其他菌株有差异显著(P0.05)。将环链棒束孢GZUIFR04XS8分别接种在2～5龄幼虫时,对同一龄期幼虫的致死率随接种浓度的增大而上升,其中,接种孢子浓度为1×10~9个/mL可致2龄幼虫100%死亡;同一接种浓度下,对幼虫致死率随幼虫龄期的增大而下降,其中,2龄幼虫的致死中浓度LC_(50)为1.28×10~5个/mL。环链棒束孢GZUIFR04XS8有较好防治斜纹夜蛾蛹和低龄幼虫的生防潜力。     

Host Range Studies for Tomato chlorosis virus, and Cucumber vein yellowing virus Transmitted by Bemisia tabaci (Gennadius)

The Bemisia tabaci (Gennadius) biotype B transmitted host range of Tomato chlorosis virus (ToCV), genus Crinivirus, Family Closteroviridae, and Cucumber vein yellowing virus (CVYV), genus Ipomovirus, Family Potyviridae, was studied. New experimental hosts were identified for each of these viruses. Seventeen species in eight plant families were assessed as potential hosts for ToCV. Infection in asymptomatic Anthriscus cereifolium (chervil) test plants by ToCV was confirmed by using a Real-Time PCR assay designed for ToCV. The presence of readily transmissible, infectious ToCV virions in A. cereifolium was confirmed by re-isolation of the virus via whitefly-transmission from A. cereifolium to Lycopersicon esculentum and A. cereifolium. This is the first report of the experimental transmission of ToCV by B. tabaci to a species within the Umbelliferae. All other hosts assessed for the presence of ToCV were found to be uninfected. Ten species in five families were assessed as potential hosts for CVYV. The CVYV host range identified included some important crops and common weeds, such as L. esculentum, Nicotiana tabacum, A. cereifolium, Datura stramonium, Nicotiana benthamiana, Nicotiana clevlandii and Cucumis sativus. Symptoms were present on D. stramonium, N. benthamiana and C. sativus control plants. The presence of infectious whitefly transmitted CVYV virions was confirmed solely for D. stramonium and N. tabacum, following re-isolation of the virus via B. tabaci transmission from all infected species to C. sativus. This is the␣first report of experimental CVYV transmission by B. tabaci to non-cucurbitaceous crop and weed hosts belonging to the Solanaceae or Umbelliferae.     

Toxicity and feeding deterrence of crude toxin extracts of Lecanicillium (Verticillium) lecanii (Hyphomycetes) against sweet potato whitefly, Bemisia tabaci (Homoptera: Aleyrodidae)

Crude toxins [toxin(V3450) and toxin(Vp28,) extracted from Lecanicillium (Verticillium) lecanii (Zimmermann) Gams & Zare strain V3450 and Vp28 respectively] were tested for contact toxicity, feeding deterrence and repellent activity against the sweet potato whitefly, Bemisia tabaci (Gennadius) (Homoptera: Aleyrodidae). Both toxins showed ovicidal activity to eggs, with LC(50) values of 447 and 629 mg L(-1) respectively. Nymphs of B. tabaci were the most susceptible stages (LC(50) values were calculated at 111 mg L(-1) for toxin(V3450) and 216 mg L(-1) for toxin(Vp28)), and adults were the second most susceptible stages (48 h LC(50) values were calculated at 178 mg L(-1) for toxin(V3450) and 438 mg L(-1) for toxin(Vp28)). Applied to seedlings at a concentration of 400 mg L(-1), the toxins significantly (P < 0.001) reduced the hatching of whitefly eggs and the subsequent survival rate of the nymphs, and the emergence and fecundity of the progeny adults. Both toxins exhibited repellent activity at low concentration (100 mg L(-1)), with repellency index (RI) values of 0.645 for toxin(V3450) and 0.642 for toxin(Vp28), and antifeedant activity at high concentration (1000 mg L(-1)) to adults, with antifeedant index (AFI) values of 0.713 for toxin(V3450) and 0.749 for toxin(Vp28). The results of the present study demonstrate the toxicity, repellence and antifeedant properties of the fungi metabolite toxins on B. tabaci, which might develop as environmentally friendly plant protectant(s).     

近10年我国烟粉虱发生为害及防治研究进展

烟粉虱是我国重要农业害虫,近10年来我国烟粉虱发生为害呈现以下特点:烟粉虱的优势生物型/隐种由B型更替为Q型;传播植物病毒(如黄化曲叶病毒、番茄褪绿病毒)成为了烟粉虱重要的为害方式;烟粉虱抗药性问题逐渐突出;化学农药尤其新烟碱类杀虫剂的广泛使用是Q型烟粉虱取代B型烟粉虱的关键因素。烟粉虱的综合防控措施日益完善,抗药性治理与非化学防控措施受到重视,但是依靠农药的现状并未完全改变。本文综述了近10年来我国烟粉虱的发生为害及防治方面的概况,探讨了今后烟粉虱防控方面的研究内容。     

Insecticide resistance in Egyptian populations of the cotton whitefly,Bemisia tabaci (Hemiptera: Aleyrodidae)

Three collections of Bemisia tabaci were taken from cotton and vegetable crops at the beginning of the growing season in Egypt. These displayed marked resistance to the carbamates carbosulfan (ca 20- to 50-fold) and aldicarb (ca 40- to 80-fold) and moderate resistance to the pyrethroids cypermethrin (ca 10- to 30-fold) and lambda-cyhalothrin (ca 10- to 25-fold). They displayed no resistance to the organophosphates profenofos and pirimiphos-methyl, or to imidacloprid. Another population, collected at the end of the growing season, differed markedly in its response. In this population, resistance to carbosulfan remained high (ca 40-fold), resistance to profenofos and cypermethrin was increased (ca 20- and 50-fold respectively) and a slight resistance to imidacloprid was detected (ca 6-fold). Resistance to cypermethrin and profenofos was shown to be similar among adults and nymphs. Irrespective of collection date, none of the populations showed resistance to pyriproxyfen. These Egyptian populations were compared with two representative Israeli populations. The differences between their resistance profiles is discussed in terms of their collection date, their geographical proximity and the patterns of insecticide use at their sites of collection.     

Populations of predators and parasitoids of Bemisia tabaci (Hemiptera: Aleyrodidae) after the application of eight biorational insecticides in vegetable crops

BACKGROUND: The sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), is an important pest of vegetables and many other crops worldwide. Eight biorational insecticides (based on oil, plant derivatives, insect growth regulator and fungus) were evaluated in the field for their influence on populations of six natural enemies of B. tabaci. Natural populations of two predators [Chrysoperla carnea Stephen (Neuroptera: Chrysopidae) and Orius spp. (Hemiptera: Anthocoridae)] and two genera of parasitoids [Encarsia spp. and Eretmocerus spp. (Hymenoptera: Aphelinidae)] were evaluated in eggplant (Solanum melongena L.). Also, augmented field populations of three predators [C. carnea, Coccinella undecimpunctata L. (Coleoptera: Coccinellidae) and Macrolophus caliginosus (Wagner) (Hemiptera: Miridae)] were evaluated in cabbage (Brassica oleracea var. capitata L.), cucumber (Cucumis sativus L.) and squash (Cucurbita pepo L.). RESULTS: Regardless of natural enemy or crop, jojoba oil, Biovar and Neemix had the least effect on abundance of the natural enemies in comparison with the other insecticides during a 14 day evaluation period. Conversely, Admiral, KZ oil, Mesrona oil, Mesrona oil + sulfur and natural oil had a high detrimental effect on abundance of the natural enemies. CONCLUSION: These results demonstrate the differential effects of biorational insecticides for whitefly control on predators and parasitoids in the field. Published 2011 by John Wiley & Sons, Ltd.     

温度和烟粉虱寄主植物对海氏桨角蚜小蜂生物学特性的影响

海氏桨角蚜小蜂Eretmocerus hayati(Zolnerowich and Rose)原产于巴基斯坦,是B型烟粉虱Bemisia tabaci (Gennadius)的一种有效天敌.本文报道了不同温度条件(20、22、26、30、34℃,RH65%±5%,光周期14L:10D)和饲养在不同寄主植物--番茄、黄瓜、甘蓝上(26℃,RH65%±5%,光周期14L:10D)烟粉虱对海氏桨角蚜小蜂生物学特性的影响.结果表明,在20℃和30℃恒温条件下,该蜂寄生在番茄上饲养的烟粉虱的发育历期分别为31.7d和12.4d,完成发育的有效积温为247日·度,发育起点温度为11.9℃.在26℃恒温条件下,该蜂寄生番茄、黄瓜和甘蓝上的烟粉虱若虫时,卵至成蜂羽化的发育历期分别为15.7、16.1和15.2d,相应存活率分别为74.6%、72.1%和78.7%,雌蜂寿命分别为7.4、7.6和8.ld,平均繁殖量分别为67.2、62.3和74.7粒卵.本研究结果对海氏桨角蚜小蜂的大量饲养和田间释放具有指导作用.     

新疆两种粉虱的酯酶和过氧化物酶同工酶的比较研究

应用电泳分析方法 ,对乌鲁木齐地区所发生的温室白粉虱和烟粉虱进行了酯酶同工酶、过氧化物同工酶的比较研究。结果表明 :两种粉虱的酶谱有明显的种间差异。温室白粉虱的酯酶酶谱可分 2组区带 ;过氧化物酶酶谱可分 5组区带。烟粉虱的酯酶酶谱可分 5组区带 ;过氧化物酶酶谱可分 4组区带     

Baeoentedon balios (Hymenoptera: Eulophidae): a parasitoid of ficus whitefly,Singhiella simplex (Singh) (Hemiptera: Aleyrodidae), new to the United States

A new host and distribution record is provided for the whitefly parasitoid Baeoentedon balios Wang, Huang, & Polaszek (Hymenoptera: Eulophidae). Specimens were reared from ficus whitefly, Singhiella simplex (Singh) (Hemiptera: Aleyrodidae), in St. Petersburg, FL, USA, representing the second confirmed host for B. balios, as well as the first record of Baeoentedon Girault from the Western Hemisphere.     

龟纹瓢虫对烟粉虱和棉蚜取食选择及适合度比较研究

基于近年来棉田烟粉虱数量上升并与棉蚜呈混合或交替发生的态势,比较研究了棉田优势捕食性天敌龟纹瓢虫对棉蚜和烟粉虱的取食偏好和食物适合度.结果显示,龟纹瓢虫不同虫态对烟粉虱若虫和棉蚜均具有较好的捕食作用;在棉蚜和烟粉虱若虫不同比例共存的情况下,龟纹瓢虫成虫均显著地偏好取食棉蚜;空间增大和蚜虫数量不足有助于增加龟纹瓢虫成虫对烟粉虱若虫的控制效应.取食烟粉虱若虫和棉蚜若虫的龟纹瓢虫幼虫均能完成生长发育,对后代成虫性比亦无影响;但取食烟粉虱若虫的龟纹瓢虫幼虫期延长3d,死亡率升高5.45倍,幼虫和成虫体重明显减轻;成虫取食烟粉虱若虫不能满足其产卵的营养需求.综合分析认为,棉田具有一定数量(经济域值以下)的棉蚜,有利于增加龟纹瓢虫对烟粉虱的控制效应.