Role of leaf glandular trichomes of melon plants in deterrence of Aphis gossypii Glover

External characteristics of the leaf epidermis and their effects on behaviour of Aphis gossypii Glover were evaluated in two Cucumis melo L. genotypes, ‘Bola de Oro’ (aphid susceptible) and TGR‐1551 (aphid resistant) in order to explore their role in the early rejection of TGR‐1551 by this aphid. No differential effects of epicuticular waxes on aphid behaviour were observed. The type, distribution and number of trichomes on melon leaves were also studied. Pubescence in melon, measured as the number of non‐glandular trichomes per cm², was not sufficient to prevent aphid settling. However, there was a high density of type I glandular trichomes on leaves of the aphid‐resistant genotype. According to microscopic observations and stain testing, these trichomes store and secrete phenols and flavonoids. Free‐choice tests were conducted to determine the effect of these glandular trichomes on A. gossypii preference, revealing that aphids reject leaf disks of TGR‐1551 from the onset of the experiment. Additional experiments after removal of leaf type I glandular trichome exudates showed that A. gossypii preferred washed TGR‐1551 leaf disks over unwashed disks, while this effect was not observed in experiments using washed and unwashed ‘Bola de Oro’ leaf disks. These results suggest that a high density of glandular trichomes and chemicals secreted by them deter A. gossypii and disturb aphid settling on TGR‐1551.     

不同温度条件对棉蚜、棉长管蚜种间竞争关系的影响

【目的】棉蚜Aphis gossypii和棉长管蚜Acyrthosiphon gossypii是棉花上的共存种,本文拟明确不同恒温条件下两种蚜虫单种和共存时的种群动态、有翅蚜发生及在棉株上的分布情况,探讨温度对两者种间竞争的作用。【方法】棉蚜、棉长管蚜单种、混合初始等蚜量设置,分别置于室内21、24和27℃恒温条件下,系统调查记录各处理种群数量、有翅蚜数量及在棉株上的分布,应用内禀增长率rm、空间分布情况、有翅蚜比例为竞争判别指标。【结果】棉蚜单种种群过程的rm均大于棉长管蚜,共存条件下一种对另一种蚜虫的rm均没有显著影响;棉蚜种群97%以上在叶片活动,棉长管蚜在叶片的比例为55%~75%;同一温度条件,两种共存不影响对方在棉花叶片和茎秆上的分布;棉蚜和棉长管蚜主要分布于棉花中上部。随温度升高,共存种群中棉蚜向棉株下部移动的比例增加,单种和共存种群棉长管蚜趋向于棉株上部移动。同一温度条件下,共存对棉蚜上下分布没有明显影响。21℃和27℃棉蚜的存在对棉长管蚜没有显著影响,但24℃时共存可使棉长管蚜在下部的比例明显增加;随温度的升高,棉蚜有翅蚜比例下降显著,而棉长管蚜无显著变化。【结论】适温范围内,两种蚜虫种间竞争的存在不影响彼此的内在繁殖能力,棉蚜比棉长管蚜具有更强的内在竞争能力;温度对棉蚜在竞争活动空间上的影响不明显,而对棉长管蚜的上下位置的选择有一定作用;种间竞争和种内竞争加速棉蚜有翅蚜的发生。     

Aspects of insecticide resistance in the melon and cotton aphid, Aphis gossypii (Hemiptera: Aphididae)

Strains of the aphid Aphis gossypii, taken from cucumber in UK glasshouses were tested for resistance to pirimicarb, diazinon and heptenophos. Compared to a susceptible strain, resistance factors to diazinon of up to 659 were found in populations collected between 1987 and 1989. Compared to the same susceptible strain, diazinon-resistant populations also showed a reduced response to heptenophos. All field populations tested against pirimicarb were resistant. Host plant preference tests showed that all strains (including stock cultures) tested could readily breed on cotton. However strains originally collected from chrysanthemum did not transfer to cucumber and likewise strains from cucumber would not colonise chrysanthemum. Polyacrylamide gel electrophoresis of four of the aphid strains showed differences in migration rates and intensity of staining of esterase bands. Intensity of staining was correlated with the degree of diazinon resistance.     

Influences of fertilization on Aphis gossypii and insecticide usage

Abstract: Fertilization levels for ornamental crops may influence pest population dynamics, crop quality, and pest management strategy. We examined the effect of fertilization on population growth and within‐plant distribution of melon or cotton aphid, Aphis gossypii Glover, on potted chrysanthemum, Dendranthema grandiflora (Tzvelev). In terms of pest management implications, we also investigated the effect of fertilization on the number of insecticide applications needed to control A. gossypii on potted chrysanthemum. Population growth rate of A. gossypii increased with fertilization levels from 0 to 38 ppm N and reached a plateau from 38 to 488 ppm N. Increased fertilization beyond 38 ppm N, 10% of the commercial standard, did not result in higher aphid number. Aphids responded to nutrient availability of plants by distributing themselves in areas with higher level of nitrogen. More aphids were found in the apical and middle strata of the plants than the basal stratum, which had the lowest nitrogen content. Leaf nitrogen content increased with increased fertilization level and was consistently higher in the apical and middle strata than the basal stratum. Increased fertilization from 0 to 375 ppm N did not result in higher number of insecticide applications. All three insecticides (bifenthrin, kinoprene or pymetrozine) were effective in keeping the aphid infestation below a pre‐determined level, five aphids per plant, but pymetrozine required the least number of applications. For chrysanthemum, a fast‐growing crop and heavy utilizer of nitrogen, increased fertilization shortened the time to flowering, which would allow growers to harvest their crop sooner and reduce the time for aphid population growth. Reduction in time to harvest could result in significant reduction of insecticide usage by reducing the time for aphid population growth. As a result, high fertilization together with minimal runoff may be a useful tactic to an integrated pest management (IPM) programme for managing A. gossypii on potted chrysanthemums.     

棉蚜与其天敌种群分布格局的关系

对棉蚜与其多种天敌在数、时、空方面关系的研究表明,龟纹瓢虫与棉蚜种群数量极相关,两者发生数量高峰期和低谷期均是同步的,龟纹瓢虫对棉蚜种群有明显的控制作用,龟纹瓢虫、草间小黑株及棉蚜种群的三维空间格乙为聚集型,棉蚜和草间小黑蚜个体间互相吸引,龟纹瓢虫个体间互相排斥。     

瑞香狼毒素对蚜虫防治的初步试验

以从瑞香狼毒（Stellera chamaejasme L.）中提取获得天然活性物质1,5-二苯基-1-戊酮、1,5-二苯基-2-烯-1-戊酮为主体成分,研制成生物灭蚜剂（LX-1）,对农业上几类重要蚜虫进行了防治应用的初步试验.结果表明,室内对棉蚜和烟蚜的触杀作用24 h 的LC50分别为81.73 mg/L和83.32 mg/L;并利用该制剂对棉蚜、烟蚜和麦蚜进行了田间防治试验,施药后3～5天防效达到峰值,2400倍稀释度下,防效达93%～99%,显示了较好的应用前景.     

Esterase variation and insecticide resistance in Japanese Aphis gossypii

Nine clones of Aphis gossypii Glover (Homoptera: Aphididae) collected from five localities in Japan were tested for esterase activity and resistance to two insecticides. These clones were classified into six types according to esterase pattern and activity detected by electrophoresis. Three clones with very high esterase activity (Type-1) were moderately resistant to malathion and very highly so to pirimicarb. Of six clones with moderate esterase activity one clone (T-4a) was susceptible to malathion but highly resistant to pirimicarb, whereas five clones (T-2, 3a, 3b and 4b) were susceptible to both insecticides. Thus malathion resistance is positively correlated with high esterase activity, whereas pirimicarb resistance is not necessarily so. It is suggested that high esterase activity plays an important role in resistance to these insecticides but that another mechanism is also responsible for resistance to pirimicarb.

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Variations de l'activité estérase et résistance aux insecticides chez des Aphis gossypii japonais

Résumé L'activité estérase et la résistance aux insecticides ont été examinées chez 9 clones de A. gossypii, récoltés dans 5 sites du Japon. Ces clones ont été groupés en 6 types suivant le comportement et l'activité de l'estérase mis en évidence par électrophorèse. 3 clones ont présenté une activité estérase très élevée (type 1) et des résistances, moyenne pour le malathion et très élevée pour le pirimicarbe. Parmi les 6 clones ayant une activité estérase modérée, un clone (T-4a) était sensible au malathion mais très résistant au pirimicarbe, tandis que les 5 autres clones (T-2, 3a, 3b et 4b) étaient très sensibles aux deux insecticides. Ainsi, la résistance au malathion présente une forte corrélation avec une activité estérase élevée, sans qu'il n'en soit nécessairement de même pour la résistance au pirimicarbe. Une hypothèse est émise suivant laquelle l'activité estérase élevée joue un rôle important dans la résistance à ces deux insecticides, mais qu'un autre mécanisme intervient aussi dans la résistance au pirimicarbe.

     

棉蚜飞行行为与卵巢发育的关系

采用高空黄盆诱蚜、卵巢解剖、体型测量及起飞角度测定方法研究了南京地区棉蚜飞行行为与卵巢发育间的关系。结果表明 ,5月份高空诱蚜的卵巢小管数与个体大小间成显著正相关 ,而木槿上有翅蚜的体长与卵巢小管数间相关不显著。棉蚜起飞角度的大小与卵巢小管数目呈显著的负相关 ,棉蚜的最大起飞角度为 4 4°左右。     

Relationship between Aphis gossypii (Homoptera: Aphididae) and sticky lint in cotton

The study was conducted in the northern Texas Rolling Plains in 1999 to define the relationship between number of cotton aphids, Aphis gossypii Glover, and resulting contamination of cotton lint by honeydew. Whole-plot treatments were three furrow irrigation management treatments: cotton grown without supplemental irrigation (dryland), irrigated cotton with last irrigation in mid August, and irrigated cotton with last irrigation in late August. Subplots within each irrigation treatment included an untreated check, a plot treated with lambda-cyhalothrin to stimulate aphid population increase, a plot treated with lambda-cyhalothrin followed by pymetrozine after aphids began to increase, and a plot treated with lambda-cyhalothrin followed by thiamethoxam after aphids began to increase. Cotton aphids were counted on leaves picked from the top and bottom half of the plant. Cotton lint was analyzed for contamination by glucose, fructose, sucrose, and melezitose secreted by cotton aphids, and percentage leaf moisture and nitrogen and leaf sucrose concentrations were determined. The manual sticky cotton thermodetector was used to determine degree of lint stickinesss. There was a significant relationship between thermodetector counts and melezitose contamination on lint, and a melezitose concentration of 90.9 microg/g of lint was associated with a thermodetector count of 10, the threshold for sticky lint problems in textile mills. An equation was developed to estimate melezitose concentration on lint as a function of average numbers of aphids per leaf and the interaction between percentage leaf moisture and nitrogen. The number of aphids per leaf associated with a melezitose concentration of 90.9 microg/g of lint ranged from 11.1 to 50.1, depending on percentage leaf moisture and nitrogen. The threshold for sticky lint problems occurred when aphid numbers ranged between 11.1 and 50.1 per leaf after bolls open.     

棉蚜及龟纹瓢虫空间格局的地学统计学研究

应用地学统计学的原理和方法研究了不同时期棉蚜及龟纹瓢虫种群的空间结构和空间生。结果表明,不同时期棉蚜种群的关变异函数曲线皆为球型,其空间格局为聚集型,变程在８．２１￣１０．８１ｍ之间;龟纹瓢虫种群的拟合半变异函数曲线也表现为球型,呈聚集空间格局,空间变程在８．０１￣１４．２５ｍ之间,并与棉蚜种群在数量和空间上有较强的追随关系,说明龟纹瓢虫种群是棉蚜种群的优势种天敌。     

Polymorphisms in a carboxylesterase gene between organophosphate-resistant and -susceptible Aphis gossypii (Homoptera: Aphididae)

Resistance to omethoate was suppressible by the hydrolytic enzyme inhibitor SSS-tributyl phosphorotrithioate in a laboratory-selected resistant cotton aphid, Aphis gossypii Glover, strain, suggesting the involvement of hydrolytic enzymes in the detoxification process. The kinetic properties of carboxylesterases from both resistant and susceptible cotton aphids were characterized by four acyl ester substrates: alpha-naphthyl acetate (alpha-NA), alpha-naphthyl butyrate (alpha-NB), alpha-naphthyl phosphate (alpha-NP), and beta-naphthyl phosphate (beta-NP). No significant differences of carboxylesterase activity were found between resistant and susceptible strains by using either alpha-NP or beta-NP as substrates. In contrast, the susceptible A. gossypii exhibited significantly higher activity compared with resistant aphids with either alpha-NA or alpha-NB as substrates. To understand the molecular basis of this esterase-mediated resistance, carboxylesterase genes from both strains were cloned. Two genes share 99.4% identity at the nucleic acid level and 99.2% identity at the amino acid level. The full length of the cDNA opening reading frame is 1581 bp, encoding 526 amino acids. Four amino acid substitutions, Thr210 --> Met210, Asn294 --> Lys294, Gly408 --> Asp408, and Ser441 --> Phe441, were identified in the resistant strain. Probing of Southern blots with the 0.5 kb esterase fragment showed the same banding patterns and intensities with genomic DNA extracts from both resistant and susceptible A. gossypii. Furthermore, the MspI and HpaII fragments are the same in both strains, indicating there is no methylation of sequences detected by the probe. The combined results suggest that the structural gene substitution is likely the molecular basis of the organophosphate resistance in this laboratory-selected cotton aphid strain.     

Influence of vermicompost and cucumber cultivar on population growth of Aphis gossypii Glover

The melon aphid, Aphis gossypii Glover (Hem., Aphididae), is one of the most important pests of cucumber throughout the world. This aphid has a short generation time and high fecundity that result in an enormous reproductive potential, especially in cucumber‐growing greenhouses. Vermicomposts, which are produced by exploiting interactions between earthworms and microorganisms, may enhance plant growth and plant resistance against some pests and disease. In this study, the effects of vermicompost and cucumber cultivar (Cucumis sativus L.) on infestation levels with A. gossypii were evaluated. We conducted a factorial experiment with two cucumber cultivars (Royal and Storm) and five concentrations of vermicompost in the soil, including 0% (control), 10%, 20%, 30% and 50%, employing a randomized complete block design with four replicates. The experiment was conducted in a growth chamber at 25 ± 2°C, 65 ± 10% RH and a photoperiod of 14 L: 10 D h. The number of aphids was counted 3, 5, 7, 9, 12, 15, 18 and 21 days after infestation of cucumber seedlings by aphids. We found that in all vermicompost‐amended treatments, aphid numbers were lower than when plants were grown in soil without any vermicompost. The highest and lowest aphid counts occurred in the control treatment on cucumbers of the Royal cultivar and in the 30% and 50% vermicompost treatments on the storm cultivar, respectively. Overall, our study showed that the application of vermicompost has a high potential for reducing A. gossypii populations in cucumber cultures.     

Evolutionary perspectives on the links between mitochondrial genotype and disease phenotype

Background

Disorders of the mitochondrial respiratory chain are heterogeneous in their symptoms and underlying genetics. Simple links between candidate mutations and expression of disease phenotype typically do not exist. It thus remains unclear how the genetic variation in the mitochondrial genome contributes to the phenotypic expression of complex traits and disease phenotypes.

Scope of review

I summarize the basic genetic processes known to underpin mitochondrial disease. I highlight other plausible processes, drawn from the evolutionary biological literature, whose contribution to mitochondrial disease expression remains largely empirically unexplored. I highlight recent advances to the field, and discuss common-ground and -goals shared by researchers across medical and evolutionary domains.

Major conclusions

Mitochondrial genetic variance is linked to phenotypic variance across a variety of traits (e.g. reproductive function, life expectancy) fundamental to the upkeep of good health. Evolutionary theory predicts that mitochondrial genomes are destined to accumulate male-harming (but female-friendly) mutations, and this prediction has received proof-of-principle support. Furthermore, mitochondrial effects on the phenotype are typically manifested via interactions between mitochondrial and nuclear genes. Thus, whether a mitochondrial mutation is pathogenic in effect can depend on the nuclear genotype in which is it expressed.

General significance

Many disease phenotypes associated with OXPHOS malfunction might be determined by the outcomes of mitochondrial–nuclear interactions, and by the evolutionary forces that historically shaped mitochondrial DNA (mtDNA) sequences. Concepts and results drawn from the evolutionary sciences can have broad, but currently under-utilized, applicability to the medical sciences and provide new insights into understanding the complex genetics of mitochondrial disease. This article is part of a Special Issue entitled Frontiers of Mitochondrial Research.     

棉蚜啶虫脒抗性种群交互抗性和增效剂增效作用的研究

【目的】明确棉蚜Aphis gossypii Glover啶虫脒抗性品系与其它杀虫剂的交互抗性现状以及增效剂的增效作用,为延缓和治理棉蚜对啶虫脒的抗性提供依据。【方法】采用单头反选育和群体汰选的方式,获得了棉蚜啶虫脒敏感和抗性品系;采用叶片药膜法测定了13种杀虫剂对啶虫脒的交互抗性以及增效剂对啶虫脒的增效作用。【结果】经过室内棉蚜敏感和抗性品系的筛选,获得了相对抗性倍数为82.33倍的棉蚜啶虫脒抗性品系。棉蚜啶虫脒抗性品系的交互抗性谱的研究表明,交互抗性倍数小于5的药剂为:吡蚜酮,甲基阿维菌素;交互抗性倍数在5~10倍的药剂为:噻虫嗪,联苯菊酯,毒死蜱,马拉硫磷,丙溴磷,辛硫磷;交互抗性倍数在10~15倍的药剂为:硫丹,阿维菌素,高效氯氰菊酯,三唑磷,氧化乐果;交互抗性倍数大于1 5倍的药剂为:吡虫啉。增效剂实验表明,TPP和PBO在啶虫脒敏感品系中增效作用不明显,但在抗性品系中增效作用显著。在啶虫脒抗性品系中的增效比为1.77、1.61,在啶虫脒敏感品系中的增效比为1.02、1.03。DEM在啶虫脒抗性、敏感品系中的增效作用均不明显,增效比为1.04、1.02。TPP和PBO对啶虫脒有很好的增效作用。以室内棉蚜敏感品系(LC_(50)为0.180 mg/L)为基础,对新疆各主要棉区的棉蚜种群进行了啶虫脒药剂的抗性调查,结果表明新疆各主要棉区棉蚜对啶虫脒的相对抗性倍数为6.1~22.0倍。【结论】由此说明新疆主要棉区棉蚜对啶虫脒具有一定的抗性风险,生产中可以利用无交互抗性的吡蚜酮和甲基阿维菌素来治理抗性棉蚜种群。     

Biological control of Aphis gossypii on pepper plant using Coccinella algerica

To calibrate biological control in pepper plant against Aphis gossypii using Coccinella algerica different experimentation were made. The consumption of C. algerica during the larval stage was enumerated in laboratory conditions. The densities (1, 4, 8 larvae/plant) to L2 stage of C. algerica necessarily to decrease aphid's populations were determined in plant pepper and the daily consumption in the pepper plant at the different densities was calculated. The density with 8 larvae at semi natural conditions is higher significantly. In protected crop of pepper, different releases to C. algerica were made with eggs, second stage larva and with ladybird before infestation with A. gossypii. A strategy to introduce L2 stage is preferred than the release with punters of C. algerica at different densities. At the same, the Introduce L2 stage is compared to release the C. algerica ladybird before the infestation of A. gossypii in the protected crops. The activity of ladybird has been maintained in the protected crop and it was shown when the infestation appeared.     

Host plants of Aphis gossypii (Aphididae), vector of virus of Cucumis melo melon (Cucurbitaceae) in Costa Rica]

Plant species associated with commercial melon crops and surrounding areas were examined to identity the natural host plants of Aphis gossypii Glover. The study was conducted in two farms located in different melon production areas and plant life zones of Costa Rica. Plant species diversity, percent coverage and distribution over time were recorded during one year. Differences between locations were observed. A total of 86 plant species (49 families) and 72 plant species (40 families) were identified associated to the crop in farms A and B, respectively. In both farms a total of 24 species plants (16 families) were colonized by A. gossypii and 16 (10 families) are new reports of host plant species for this aphid. The new reports are: Justicia comata, Tetramerium nervosum, Alternanthera pubiflora, Cassia massoni, C. reticulata, Cleome viscosa, C. spinosa, Croton argenteus, Caperonia palustris, Chamaesyce gyssopilopia, Phyllantus amarus, Sida decumbens, Ludwigia erecta, Passiflora foetida, Guazuma ulmifolia and Corchorus orinocensis.     

Ecological specialization of the aphid Aphis gossypii Glover on cultivated host plants

Many plant-feeding insect species considered to be polyphagous are in fact composed of genetically differentiated sympatric populations that use different hosts and between which gene flow still exists. We studied the population genetic structure of the cotton-melon aphid Aphis gossypii that is considered as one of the most polyphagous aphid species. We used eight microsatellites to analyse the genetic diversity of numerous samples of A. gossypii collected over several years at a large geographical scale on annual crops from different plant families. The number of multilocus genotypes detected was extremely low and the genotypes were found to be associated with host plants. Five host races were unambiguously identified (Cucurbitaceae, cotton, eggplant, potato and chili- or sweet pepper). These host races were dominated by asexual clones. Plant transfer experiments using several specialized clones further confirmed the existence of host-associated trade-offs. Finally, both genetic and experimental data suggested that plants of the genus Hibiscus may be used as refuge for the specialized clones. Resource abundance is discussed as a key factor involved in the process of ecological specialization in A. gossypii.     

高温和密度效应对棉蚜死亡和繁殖的影响

在室内采用叶子圆片培养基饲养棉蚜的方法,研究不同温度(32、34、36、38、40℃)和密度(每皿5、25、50、75)对棉蚜死亡和繁殖的影响.结果表明:随着温度的升高、密度和持续天数的增加,棉蚜累计死亡率呈上升趋势.互补重对数模型模拟结果表明:β值随着密度的增加而减小,说明随着棉蚜密度的增加,温度对棉蚜的作用减弱;不同持续天数的γj值不同,说明棉蚜条件死亡率受温度和作用时间的共同影响.双因素方差分析结果表明,温度和密度显著影响棉蚜的繁殖率,且存在交互作用.32～36℃范围内,棉蚜繁殖率随密度的增加呈降低趋势,40℃条件下,不同密度棉蚜繁殖率没有差异,说明随着温度的升高,密度对棉蚜的作用逐渐减弱.即在不同的温度区间和密度范围内,温度和密度对棉蚜的作用大小、主次发生了改变.研究结果为棉蚜种群监测、预警和改进害虫控制方法提供了科学依据.     

Effects of different temperatures and density on the survival and reproduction of Aphis gossypii on cotton plants

为探索趋近自然状态的渐变性高温胁迫对不同密度棉蚜Aphis gossypii Glover的影响,室内研究了4种不同高温模式下,不同密度(5、10、20、40)棉蚜的存活和繁殖.结果表明:随着最高温度值的升高和密度的增加,棉蚜存活率和繁殖率均呈下降趋势.当最高温度值升至40℃以上时,棉蚜存活率和繁殖率均显著下降,不同密度棉蚜存活率和繁殖率均没有差异.即随着温度的升高,密度对棉蚜的作用逐渐减弱.最高温度值为42℃时,棉蚜在3～4d内全部死亡.研究结果为提高棉蚜种群预测准确性、科学决策防治措施提供依据.     

高温对共存种棉蚜与棉长管蚜死亡及繁殖的影响

棉蚜和棉长管蚜是棉花上的共存种,为探索其年内及年际间优势地位的不同是否与两者对高温的不同响应有关,室内研究了高温胁迫(32、34、36和38℃)对棉蚜和棉长管蚜死亡及繁殖的影响.结果表明:随着温度的升高和高温持续天数的延长,棉蚜和棉长管蚜累计死亡率均升高,棉长管蚜累计死亡率高于棉蚜;两种蚜虫的每日死亡率可用互补重对数模型较好地拟合,模型估计的棉蚜和棉长管蚜半数致死温度值随高温持续天数的延长而降低,棉蚜半数致死温度高于棉长管蚜;在32 ～ 38℃范围内,两种蚜虫的繁殖率随温度的升高而降低,棉蚜繁殖率显著高于棉长管蚜,表明在32℃以上高温条件下,棉蚜比棉长管蚜更具有竞争力.随着全球气候变暖,由于棉蚜比棉长管蚜更耐高温,推测未来棉蚜比棉长管蚜竞争优势更加明显.