三种寄主植物对小菜蛾实验种群特征的影响

为明确萝卜、白菜和油菜对小菜蛾实验种群特征的影响,测定了小菜蛾对3种寄主的取食量,通过构建两性生命表比较了不同寄主植物对其实验种群发育与繁殖的影响,并综合生命表与取食量参数,评价了小菜蛾对萝卜、白菜和油菜的危害。结果显示:小菜蛾幼虫在萝卜、油菜和白菜上的取食量差异显著,分别为93.3、105.0和114.7 mg/头。小菜蛾取食萝卜、白菜和油菜后,其幼虫的发育历期差异显著,依次为8.6、8.5和7.6 d;种群内禀增长率依次为0.18、0.23和0.23,周限增长率为1.19、1.26和1.26,净生殖率为18.7、46.1和30.6。取食萝卜的小菜蛾各发育阶段的存活率最低。小菜蛾对各供试寄主实际危害量占理论危害量的百分比为油菜(71.8%)白菜(70.8%)萝卜(53.0%)。表明同一时间内,小菜蛾对油菜危害程度最大,白菜次之,萝卜最小。     

Toxicity,persistence and efficacy of indoxacarb and two other insecticides on Plutella xylostella (Lepidoptera: Plutellidae) immatures in cabbage

Toxicities of indoxacarb on eggs and 5-day-old larvae of diamondback moth, Plutella xylostella L., on cabbage and those of field-aged leaf residues on 5-day-old larvae were determined in the laboratory. The persistence and efficacies of indoxacarb and two other newer insecticides (spinosad and emamectin benzoate) to P. xylostella were tested under field conditions. Results from laboratory bioassays indicate that indoxacarb was highly toxic to P. xylostella larvae through food ingestion, with LC₅₀ and LC₉₀ values of 24.1 and 90.1 mg AI l ^{- 1}, respectively. However, indoxacarb had no significant effects on eggs and larvae through direct contact compared with water control. The toxicity of field-aged leaf residues of indoxacarb (0-, 3-, 5-, 7-, 10-, 14-, 17- and 21-day-old residues) declined slowly and gradually under the field conditions in South Texas. Almost all larvae died on day 5 after feeding on the leaves with 0 - 14-day residue, and the mortalities were as high as 94 and 78% for the 14- and 17-day-old leaf residues. With one application, indoxacarb suppressed P. xylostella larvae below the economic threshold for 14 - 21 days. Two field trials showed that indoxacarb at 0.05 - 0.07 kg AI ha ^{- 1} was effective against P. xylostella, providing marketable cabbage with three applications per season. In addition, indoxacarb was as effective as spinosad, and significantly more effective than emamectin benzoate.     

八种十字花科寄主植物真叶和子叶的化学成分及其对小菜蛾生长发育及生理代谢的影响

为明确小菜蛾Plutella xylostella对寄主植物真叶和子叶的适合度,于室内测定8种十字花科植物改良青杂3号、改良露头青、陕油0913、甘杂1号、超级火箕青、四月慢、绿球66和中花尖叶芥蓝真叶和子叶的营养物质和次生代谢物质的含量,并测定取食后小菜蛾幼虫的取食选择性、发育历期、蛹重、保护酶和解毒酶活性。结果显示,8种寄主植物真叶的可溶性糖、总氨基酸、单宁、类黄酮和总酚含量之间差异显著,且大部分均显著高于其子叶,8种寄主植物子叶的可溶性糖、总氨基酸、单宁、类黄酮和总酚含量之间也差异显著。小菜蛾3龄幼虫偏好取食真叶;取食8种寄主植物真叶后成虫前期的发育历期为12.3～16.3 d,取食子叶后成虫前期的发育历期为14.3～18.6 d;取食子叶的蛹重明显低于取食其真叶;取食8种寄主植物真叶的小菜蛾幼虫体内超氧化物歧化酶（superoxide dismutase,SOD）、过氧化物酶（peroxidase,POD）、过氧化氢酶（catalase,CAT）、谷胱甘肽S-转移酶（glutathione S-transferase,GST）、羧酸酯酶（carboxylesterase,Car...     

喹硫磷在茶叶中的残留降解

在杭州和长沙两地两年用不同剂量、不同施药方法进行的研究表明,喹硫磷在茶树鲜叶上降解速度中等,1天后的降解率平均7.15％,降解速度低于辛硫磷、马拉硫磷、敌敌畏等农药。用25％乳剂800倍液喷施后5天鲜叶中残留量低于10ppm,10天后低于1ppm,降解速率常数(K)0.47±0.06天,半衰期1.37±0.02天。降雨对喹硫磷在茶树上的降解有一定影响,尤其在施药后的近期。对成茶中在喷后不同间隔天数的残留量、含喹硫磷残留的鲜叶在加工过程中的降解率、成茶中喹硫磷残留量在泡茶时的浸出率,均进行了测定,并讨论了喷后不同间隔期鲜叶上的残留量和茶尺蠖幼虫致死剂量间的关系。建议喹硫磷在成茶中允许残留标准暂订为0.2ppm,茶叶喷施25％乳油800倍液后的安全间隔期为8—10天。     

Locomotory behaviour of susceptible and resistant <Emphasis Type="Italic">Plutella xylostella (Linnaeus)</Emphasis> (Lepidoptera: Plutellidae)

Locomotory behaviour of insecticide-resistant and susceptible populations of diamondback moth, Plutella xylostella (Linnaeus), a challenging insect-pest of cruciferous vegetable crops round the globe, was studied with the help of Ethovision. Larvae from the susceptible population of P. xylostella travelled more distance on insecticide-treated or untreated surface and consequently their speed was also more as compared to those taken from the insecticide-resistant population.Whereas, the turn angle of larvae from insecticide-resistant population was significantly higher as compared to those from susceptible population. The resistant larvae travelled significantly less distance (260.68 cm/5 min) on treated-surface (with LC₅₀ value of endosulfan, quinalphos, fenvalerate and spinosad) with more value of turn angle (231.16°) than the susceptible ones which moved faster (517.23 cm/5 min) with less value of turn angle (100.63°). Influence of varying temperatures on locomotory behaviour of larvae from the susceptible and resistant population of P. xylostella was also studied and observed that susceptible P. xylostella larvae travelled significantly greater distance as compared to the larvae from insecticide-resistant population, at different temperatures. Locomotory behaviour of larvae of P. xylostella also changes with food conditions. Resistant larvae starved for 24 h travelled significantly lesser distance (147.29 cm) as compared to unstarved ones (332.50 cm). Similar trend in behaviour was also recorded with respect to speed of larvae of P. xylostella. Larvae turn more frequently when kept without food (starved) than those fed normally; the turn angle was significantly higher (290.07°) for resistant larvae and for susceptible larvae it was lesser i.e. 151.55°, when kept at starved conditions. Hence, certain pronounced behavioural differences were registered in locomotion of insecticide-resistant P. xylostella as compared to the susceptible one and this knowledge would help to find effective management solutions to P. xylostella.     

苏芸金杆菌HD-1防治小菜蛾的研究

应用苏芸金杆菌 HD-1制剂,进行防治小菜蛾(Plutella xylostella L.)技术方法的研究,求出了 HD-1制剂对小菜蛾2、3、4龄幼虫杀虫曲线的回归直线方程分别为 y=8.18+2x,y=7.92+2x,y=6.93+2.1x。田间试验结果说明:每亩应用 HD-1制剂0.1～0.15公斤加水75～100公斤,防治小菜蛾效果达90%,高于常用化学农药,防治费用在0.3元左右,低于常用化学农药。HD-1制剂对天敌昆虫、蜘蛛等无不良影响。     

Effects of interactions between host plants and selective insecticides on larvae of Plutella xylostella L. (Lepidoptera: Yponomeutidae) in the laboratory

The residual toxicity of two selective insecticides, teflubenzuron (acylurea) and Bacillus thuringiensis Berliner ssp. aizawai (microbial), to laboratory and field strains of Plutella xylostella L. was shown in the laboratory to be significantly affected by leaf nutritional status, other host-plant resistance factors, cultivation method and plant age. With plants offering some degree of host-plant resistance, the toxicity of the insecticides was either increased or decreased compared with highly susceptible plants, depending on the specific nature of the plant-herbivore interaction. Differences in residual toxicity of the insecticides varied up to nine-fold on different host plants (=host-plant- + insecticide-induced mortality) despite less than four-fold differences in P. xylostella mortality in controls (=host-plant-induced mortality alone). Host-plant nutritional status also had a substantial effect on the damage potential of larvae. Different response times by P. xylostella to the two insecticides tested on host plants of varying nutritional status were related to the contrasting modes of action of the respective active ingredients. The present studies suggest that insecticides applied to Brassica oleracea L. var. capitata with partial plant resistance may contribute to improved control of P. xylostella. A conceptual model is used to describe likely mortality responses by macrophagous larvae to insecticides applied to plants of varying resistance status. The implications of the findings in relation to the integrated management of P. xylostella are considered.     

夏玉米苗期二点委夜蛾防治指标

为有效防治夏玉米苗期二点委夜蛾的为害,通过人工接虫方法研究了其幼虫虫口密度(x)与玉米缺苗率(y)的关系,采用人工去苗模拟为害方法研究了玉米缺苗率(y)与产量损失(z)的关系,并提出了夏玉米苗期二点委夜蛾的防治指标。结果显示,虫口密度为1、3头/株时,无缺苗现象,虫口密度为5、10、20和30头/株时,缺苗率分别为19.4%、22.8%、44.4%和49.6%。玉米缺苗率随着虫口密度增大而升高,二者呈显著二次线性相关:y=-0.0609x2+3.636x-4.5306,R2为9564;玉米缺苗率对单株穗重、穗长、穗粗和秃尖长等均无显著影响;玉米缺苗率(y)与产量损失(z)也呈二次线性相关:z=0.0036y2+0.3077y-0.3553,R2为0.9691。根据防治的直接收益和成本,提出夏玉米苗期二点委夜蛾幼虫的防治指标为3头/株,此时玉米缺苗率为6%~7%。     

Efficacy of Azadirachta excelsa vinegar against Plutella xylostella

The diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), is considered a major pest for crucifers in Malaysia. New control materials are constantly required as P. xylostella population develops resistance to most of the insecticides used against them. In this study, vinegar derived from Azadirachta excelsa (Jack) Jacobs was evaluated against the third-instar larvae of P. xylostella and an appropriate application dose required to control the pest was determined in the laboratory trial. Results indicated A. excelsa vinegar to be a useful control measure, significantly reducing P. xylostella leaf consumption and adult size of P. xylostella. Interestingly, mortality rate of larval, pupae and adult was significantly increased by the application of A. excelsa vinegar. An in-diet EC₅₀ of 80× against larvae was achieved, whilst obvious defects in adult moth were also recorded. The results indicate that A. excelsa vinegar exhibits potential to be used against P. xylostella.     

连作晚稻三化螟为害损失与防治指标研究

三化螟幼虫在晚梗稻分蘖、圆秆、孕穗、破口期均能侵入,所形成的为害株数、为害类型和幼虫存活率与生育期有密切关系,为害丛、株增长呈S型曲线。分蘖期、孕穗—破口期引起丛、株为害率和损失率与卵块密度显著相关,每个卵块损失稻谷分别为59.11±2.99g、74.58±3.31g。考种结果表明,产量损失的主要原因是有效穗减少。在现有生产条件下,三化螟经济允许卵块密度为:分蘖期130—150块/666.7m~2,孕穗—破口期100—120块/666.7m~2;防治指标:分蘖期100—110块/666.7m~2,为害团50—60个/666.7m~2,丛为害率2.0％—3.0％,株为害率1.0％—1.5％。     

Testing and improving the effectiveness of trap crops for management of the diamondback moth Plutella xylostella (L.): a laboratory‐based study

BACKGROUND: The aim of this study was to assess white mustard (Sinapis alba L.) as a trap crop for diamondback moth [Plutella xylostella (L.)] on cauliflower [Brassica oleracea (L.) var. Lateman]. Moth behaviour on these plants and the importance of plant age and size in maintaining pest preference for trap crop plants were also investigated. RESULTS: Three times as many eggs were laid on cauliflower plants that were unprotected than on plants protected by a trap crop of white mustard. Moths remained longer on the mustard plants as a result of a doubling in the mean duration of information‐providing behaviours. Plant age had little effect on P. xylostella host preference. When plant age was constant, percentage oviposition on mustard was higher when these were larger (93%) than copresented cauliflower plants, compared with when they were smaller (68%). CONCLUSION: Trap cropping with white mustard may reduce the incidence of P. xylostella in cauliflower crops. The pest management benefits of trap crops may be maximised by using trap crop plants that are larger than the main crop plants, although relatively smaller trap crop plants may still be preferred as hosts for P. xylostella per se. Copyright © 2009 Society of Chemical Industry     

Powdered neem seed and cake for management of the banana weevil,cosmopolites sordidus, and parasitic nematodes

Field trials were conducted in Kenya with ‘Nakyetengu’, an East African highland banana cultivar (AAA-EA), highly susceptible to banana pests. Regardless of soil fertility levels, incorporation around the plant base of powdered neem(Azadirachta indica A. Juss.) seed or cake at 60-100 g/mat at 4-month intervals, gave better control of the banana weevil,Cosmopolites sordidus (Germar), and of parasitic nematodes, than that achieved with soil application of Furadan 5G (carbofuran) at 60 g/mat at 6-month intervals. Compared with untreated control, fruit yield in most of the neem treatments was significantly higher, particularly during the second cycle of crop production. Neem application conferred a net economic gain, whereas Furadan application proved uneconomical. Application of powdered neem seed or cake at higher rates (200–400 g/mat) at 6-month intervals caused phytotoxicity, resulting in drying up of banana plants before fruiting, or in ‘chokethroat’,i.e., inflorescence emergence failure.     

Pheromone‐based integrated pest management to control the diamondback moth Plutella xylostella in cabbage fields

Biorational and regular insecticide applications were evaluated for management of the diamondback moth (DBM) Plutella xylostella in cabbage (Brassica oleracea var capitata) in Karnataka State, India, in 1996 and 1997. The IPM programme, based on the pheromone trap catch threshold of eight moths per trap per night, included utilization of the parasitoid Cotesia plutellae. (250 000 adults ha⁻¹), the predator Chrysoperla carnea (2500 eggs ha⁻¹), the neem‐based chemical nimbecidine (625 ml ha⁻¹), the bacterium Bacillus thuringiensis (500 ml ha⁻¹), and the synthetic insecticide phosalone (2.8 litre ha⁻¹). The IPM programme induced a reduction of trap catches, egg and larval populations and, therefore, a low level of damage to the crop. The economic analysis showed that the cost of the IPM treatments was also considerably lower than that of ordinary insecticide practice (average of $62 relative to $123 ha⁻¹, respectively). Gross profit was also clearly higher in IPM plots than in farmer's fields, ranging from $777 to $810 ha⁻¹ in the IPM plots compared with $456 to $462 ha⁻¹ in the insecticide‐treated fields. As a consequence of lower input costs and higher gross profit, net profit in IPM treatments was even more favourable, and the economic savings associated with the utilization of the IPM programme amounted to $380 ha⁻¹ in 1996 and $410 ha⁻¹ in 1997. © 2000 Society of Chemical Industry     

Can sulfur fertilisation improve the effectiveness of trap crops for diamondback moth,Plutella xylostella (L.) (Lepidoptera: Plutellidae)?

BACKGROUND: The effect of sulfur fertilisation on chemical constituents of yellow rocket, Barbarea vulgaris (R. Br.), was studied with regard to its potential use as a trap crop for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae). Two types of B. vulgaris var. arcuata were used: the G‐type, resistant to P. xylostella and proposed as a ‘dead‐end’ trap crop, and the P‐type, not resistant to P. xylostella and used as a control. RESULTS: In G‐type B. vulgaris, sulfur fertilisation increased the content of the dominant glucosinolate (S)‐2‐hydroxy‐2‐phenylethylglucosinolate by 20%. Sulfur fertilisation did not significantly change levels of the saponins 3‐0‐β‐cellobiosylhederagenin and 3‐0‐β‐cellobiosyloleanolic acid, known to act as feeding deterrents for P. xylostella larvae. In P‐type B. vulgaris, the same levels of sulfur fertilisation did not change the glucosinolate content significantly. Two‐choice oviposition preference tests with B. vulgaris plants showed that P. xylostella laid 144% and 45% more eggs on G‐ and P‐type plants with sulfur fertilisation respectively. CONCLUSIONS: The studies suggest that sulfur fertilisation could increase the effectiveness of G‐type B. vulgaris as a trap crop for P. xylostella. The effect of plant sulfur fertilisation on P. xylostella oviposition preference is associated with a quantitative glucosinolate increase, but other compounds could also be involved. Copyright © 2010 Society of Chemical Industry     

The influence of <Emphasis Type="Italic">Aphanomyces cochlioides</Emphasis> on selected physiological processes in sugar beet leaves and yield parameters

Alterations in some physiological processes in source leaves of sugar beet—such as chlorophyll and carbohydrate concentrations, stomatal conductance, rate of net photosynthesis and transpiration, and activity of the photosynthetic apparatus during root interaction with Aphanomyces cochlioides, were investigated. The influence of time of infection on plant health, yield quality and quantity was also examined. Plants were infected at different times of their growth period: on the sowing day and 4 or 8 weeks after sowing. A variation treatment, with non-pelleted seeds infected on the sowing day, was also analyzed. The experiment showed that development of disease symptoms depends on the time of infection and seed protection. A significant root yield decrease was observed in case of late infection, as compared to the yield of plants infected on the sowing day. The fresh weight of leaves was significantly increased where there was late infection. The infected plants showed a lower content of K⁺, Na⁺ and α-amino-N than did the controls. Infection by A. cochlioides induced chlorophyll degradation mostly in older leaves with the occurrence of natural senescence processes. Chlorophyll fluorescence parameters indicated that the photosynthetic apparatus of younger leaves was more sensitive to pathogen infection, when compared to older ones. The photochemical efficiency of photosystem II was reduced in young leaves mainly due to disturbance of the water-splitting system. In plants grown from non-pelleted seeds a strong impairment of PSII was observed only in those leaves which developed during early pathogen infection. In young leaves of plants infected in the fourth week after sowing, inhibition of the rate of net photosynthesis was correlated with the increase in intercellular CO₂ concentration, indicating some disturbance in the carbon assimilation phase. In mature leaves of late infected plants the reduction of photosynthesis net rate was associated with a decrease of stomatal conductance and an increase of diffusion resistance to CO₂ and H₂O, which was also the cause of the transpiration rate inhibition. When the leaves developed during early infection, an increase of specific leaf weight and accumulation of carbohydrates was observed. In mature leaves of non-protected plants infected on the sowing day, the recovery of all physiological processes was observed together with a diminution of disease symptoms.     

Acquired resistance triggered by elicitins in tobacco and other plants

Elicitins are a family of proteins excreted byPhytophthora spp. They exhibit high sequence homology but large net charge differences. They induce necrosis in tobacco plants which then become resistant to the tobacco pathogenPhytophthora parasitica var.nicotianae. In stem-treated plants, resistance was not restricted to the site of elicitin application, but could be demonstrated by petiole inoculation at all levels on the stem. Resistance was already maximum after two days and lasted for at least two weeks. It was effective not only towardsP. p. var.nicotianae infection, but also against the unrelated pathogenSclerotinia sclerotiorum. In contrast to dichloroisonicotinic acid, an artificial inducer of systemic acquired resistance, which was increasingly effective with doses ranging from 0.25 to 5mole per plant, the basic elicitin cryptogein exhibited a threshold effect, inducing near total resistance and extensive leaf necrosis above 0.1 nmole per plant. Between 1 and 5 nmole, acidic elicitins (capsicein and parasiticein) protected tobacco plants with hardly any necrotic symptom. Elicitins exhibited similar effects in various tobacco cultivars andNicotiana species, although with quantitative differences, but induced neither necrosis nor protection in other SolanaceÆ (tomato, petunia and pepper). Among 24 additional species tested belonging to 18 botanical families, only some BrassicaceÆ, noticeably rape, exhibited symptoms in response to elicitins, in a cultivar-specific manner. Elicitins appear to be natural specific triggers for systemic acquired resistance and provide a tool for unraveling the mechanisms leading to its establishment.Abbreviations AR acquired resistance - HR hypersensitive response - INA 2,6-dichloroisonicotinic acid - Ppn Phytophthora parasitica var.nicotianae - SAR systemic acquired resistance     

Effect of partial plant resistance in brassicas on tolerance of diamondback moth (Plutella xylostella) larvae to cypermethrin

Brassica cultivars with varying degrees of partial plant resistance were fed to larvae (up to 4th instar) of the diamondback moth (DBM), Plutella xylostella, and were bioassayed by topical application of cypermethrin to investigate the interaction of plant resistance with insecticide. Larvae reared on the least preferred brassica, Minicole, showed a significantly higher LD₅₀ value than those on the most preferred brassica, Chinese cabbage. Bioassay of 4th instar DBM larvae fed on artificial diet containing pure compounds of glucosinolates revealed a negative interaction between their susceptibility to cypermethin and certain glucosinolates (in particular sinigrin), suggesting that such compounds induced the production of insecticide-detoxifying enzymes.     

沉默cadherin基因对小菜蛾敏感性的影响

钙粘蛋白(cadherin)是许多鳞翅目昆虫中苏云金芽孢杆菌(Bt)毒素的受体。利用RNAi技术对小菜蛾中肠cadherin基因进行沉默处理,明确了cadherin基因沉默对小菜蛾对Cry1Ac毒素敏感性的影响。结果表明,注射目标dsRNA后的第1天至第5天,Cry1Ac敏感及抗性小菜蛾品系cadherin的基因表达量均显著减少,尤以第2天的减少量最为明显;Cry1Ac毒力测定结果表明,沉默cadherin基因能在一定程度上提高幼虫的成活率,即可使小菜蛾对Cry1Ac毒素的敏感性降低。研究初步表明,cadherin基因的功能与小菜蛾对Cry1Ac毒素的抗性有关。     

北京地区春玉米螟害产量损失估计方法及防治指标的商榷

根据1962—1964年北京地区12块春播玉米地心叶期卵和卵虫(第一代)成活率資料,并参考国内对螟害与玉米产量損失关系的研究成果,提出了春玉米上因玉米螟为害而造成的产量損夫估計方法和药剂防治的参考指标。心叶期卵的平均成活率及其标准誤为57.4±2.9％,卵块的脫落是死亡的主要原因。幼虫期的平均成活率及其标准誤为5.64±0.89％。这两个平均成活率的变異系数都比较小,相关分析表明,百株着卵量与成长幼虫数是相关的。故可职利用卵和幼虫的平均成活率由着卵密度来估計成长幼虫密度。心叶期卵和幼虫的合計平均成活率及其标准誤为3.4±0.51％。在95％可靠性时的置信区間为3.4±1.173％,卵块的平均粒数为31.7粒。若职单株平均一虫所造成的产量損失率为5％計,可用丁式来估計产量損失: 产量損失％=[(心叶期百株累計卵块数×31.7)×(0.034±0.012)]×0.05 在經济核算士,作者初步認为职損失率1.5％作为防治标准比較合适。以此推算,欲达到这一損失率,心叶期百株累計卵块应为28块(用平均成活率計算)至21块(用成活率上界計算)。一般可定为24块。根据心叶期百株累計卵块数与累計着卵株百分率或百株高峯卵块数之間存在的相关,百株累計24块卵,相当于累計着卵株率28％,或百株高峯卵块6块。在实践上就可以用它們作为心叶期的防治指标。