Effects of pattern and timing of high temperature exposure on reproduction of the rose grain aphid, Metopolophium dirhodum

Metopolophium dirhodum (Walker) (Hemiptera: Aphididae) is one of the three most important cereal aphid species in Germany and central European countries. High temperature is known to play a detrimental role in the reproduction and survival of aphids. Detailed experiments were conducted to assess the effects of high temperatures (27, 29, 31, and 33 °C), exposure pattern (8 h day^?1 for 1, 2, 4, and 6 days), and exposure development stage (2nd, 3rd, 4th instar larvae, and adult) on the reproduction and longevity of M. dirhodum. All three factors have a significant influence on the aphids. Increasing the temperature to over 29 °C significantly decreases their lifetime fecundity and longevity. Mature aphids are more sensitive to high temperatures than younger ones. A high temperature pulse to treat aphids older than 3rd instar larvae greatly shortened their longevity and lessened their lifetime fecundity. Lifetime fecundity and longevity was found to be inversely related to exposure pattern. A high temperature pulse lasting longer than 1 week greatly reduced the lifetime fecundity and longevity. The limitation of the data collected from experiments at constant temperatures for aphid forecasting is discussed.     

Forecasting of peak population density of the rose grain aphid Metopolophium dirhodum on wheat

Suction trap catches for the period 1969 to 1984 were used to develop a forecasting system for M. dirhodum. This was achieved by using the strong relationships that exist between: a) suction trap catches of Metopolophium dirhodum at Broom's Barn and populations of the aphid in fields near Norwich, and b) winter and spring temperatures and the time when the crop became unsuitable for this aphid. This forecasting system was tested in 1985, 1986, 1987 and 1988 and successfully forecast early in the season that it would not be necessary to apply aphicides in 1987 and 1988. The use of this forecasting system would have correctly indicated that aphicide application against this aphid was unnecessary in 9 out of the 16 seasons from 1969 to 1984.     

Factors determining the pest status of the rose-grain aphid, Metopolophium dirhodum (Walker), on winter barley in the United Kingdom

To test the hypothesis that early maturation of barley affords it some resistance to cereal aphids, the colonisation, survival, growth, reproduction and emigration of M. dirhodum on barley was measured and compared with previously published results for this aphid on wheat.
Barley plants were colonised as readily as wheat plants. Survival to maturity was similar on both hosts. Relative growth rate was higher on wheat than on barley for most of the season while reproduction was similar on both. Emigration, measured alate production, was significantly higher on mature wheat than on mature barley.
It is proposed that the increase of M. dirhodum populations on barley is normally terminated early in the year directly plant maturation and consequent drying out of the leaves, resulting in the death of aphids. This is different to the situation on wheat, which matures later, and where emigration following plant induced alate induction has been shown to be the major factor affecting the decline in population growth.
These results support the hypothesis that early maturation of barley provides some resistance to M. dirhodum.     

The effect of plant phenology on the induction of alatae and the development of populations of Metopolophium dirhodum (Walker), the rose-grain aphid, on winter wheat

In field experiments apterous Metopolophium dirhodum produced significantly more alatae when reared on mature plants (milky ripe stage) than on young plants. Nymphal and adult survival and relative growth rate were little affected by the developmental stage of the host plant. Relative growth rate and fecundity were strongly related to temperature. Laboratory experiments confirmed that the developmental stage of wheat had no significant effect on survival or relative growth rate of the aphids. However, laboratory grown plants did not produce the levels of alate production seen in field crops and in the field experiments. It is suggested that in investigations into the effects of the host plant on cereal aphids field grown plants should be used whenever possible. Alate production is proposed as the major plant induced factor affecting the development of M. dirhodum populations on wheat in the field. Alatae developed on mature plants even when the number of aphids was very low.     

Host plant age and population development of a cereal aphid, Metopolophium dirhodum (Hemiptera: Aphididae)

The sudden decline following the peak in population abundance of aphids on crops of small grain cereals is attributed to the joint effect of natural enemies and plant senescence. To distinguish between these causes, a four year experiment was established in which the numbers of Metopolophium dirhodum (Walker) infesting spring wheat plots sown from April to June at c. 14 day intervals were determined. Aphid abundance in replicates sown at successive dates peaked within a period of 5-9 days (106-171 day degrees above a base temperature of 0 degrees C) although their sowing dates varied by 62-97 days (727-1106 day degrees). At the time of the aphid population peaks, plants in the different sowings differed in age (11-99 days), developmental stage (stage 15-65 on the Zadoks scale), leaf nitrogen content and shoot mass. Maximum abundance of M. dirhodum decreased with sowing date because the time available for its population increase was shorter on late than early sowings. The abundance of M. dirhodum on spring wheat was similar to its abundance on winter wheat. After reaching peak abundance, aphids declined in numbers within 3-7 days. The effect of host plant ageing on the M. dirhodumdecline thus appeared small. Natural enemies (largely mycoses), and timing of alata production may have contributed to the aphid decline.     

The influence of nitrogen fertiliser on the population development of the cereal aphids Sitobion avenae (F.) and Metopolophium dirhodum (Wlk.) on field grown winter wheat

The effect of nitrogen fertiliser on populations of the cereal aphids Sitobion avenae and Metopolophium dirhodum on winter wheat was investigated in a three year field experiment. Naturally occurring aphid populations were monitored on three nitrogen treatments; none, nitrogen application using Canopy Management guidelines (130–210 kg ha^-1) and conventional practice (190 kg ha^-1). Inoculations of laboratory reared S. avenae were used to enhance field populations on half the plots. Natural populations of M. dirhodum remained below the current UK spray threshold level of two-thirds of shoots infested at the start of flowering, or five aphids per shoot in all years, whilst populations of S. avenae exceeded the threshold in all years. The response of the two species to nitrogen differed. Significantly higher populations of M. dirhodum were recorded in both treatments which received nitrogen in all years, whilst the response of S. avenae varied between years. In 1994 and 1995 when environmental conditions favoured aphid development, higher populations were recorded in the two treatments which received nitrogen. In 1993 when high rainfall created unfavourable conditions, higher populations were recorded in the plots receiving no nitrogen. Differences in peak density and cumulative aphid index of S. avenae resulted from differences in the rate of population increase between ear emergence and peak density on the different treatments. Populations prior to ear emergence were higher in the plots which received nitrogen but the differences were not statistically significant. There was no evidence of a difference in the timing of population decline in the different treatments. In 1993 higher levels of infection by entomopathogenic fungi were observed in all treatments. Significantly higher levels of infection were recorded in the treatments receiving nitrogen, which may have accounted for the lower S. avenae populations recorded. It is possible that the larger canopies recorded in these treatments produced conditions which favoured infection by fungi, thereby limiting aphid population growth. The results indicate that application of nitrogen increases natural populations of M. dirhodum, and under favourable conditions, populations of S. avenae. However, in suboptimal climatic conditions, the application of nitrogen fertiliser can lead to lower populations of 5. avenae. The data also suggest that there is no consistent difference between a conventional and Canopy Managed approach to nitrogen fertiliser use in terms of the risk of infestation by cereal aphids.     

Effects of brief exposures to low temperature on the development, longevity and fecundity of the grain aphid Sitobion auenae (Hemiptera: Aphididae)

First instar nymphs and adults of the grain aphid Sirobion auenae that had been reared at 10°C and 20°C over a number of generations, were cooled to -5°C and -10°C for 1 h and 6 h and returned to 20°C to assess the effects of brief exposures to low temperatures (cold-pulses) on their survival. rate of development, longevity and fecundity. A strong acclimation response was observed in first instar nymphs, with significantly less mortality in groups reared to 10°C compared to 20°C. Mean development time from first instar to adult was not significantly affected by low temperature exposure at the first nymphal stage. Longevity in all groups cooled as first instars was reduced by the sub-zero cold-pulses, and was also dependent on temperature and exposure time. Acclimated aphids survived longer than non-acclimated individuals. Reproductive rate, in terms of the number of nymphs born per aphid per day, was unaffected by cold stress applied at the first instar stage. Total fecundity was however reduced, being a function of the number and longevity of the survivors. Adult aphids were less cold hardy than nymphs; mortality was higher at -10°C than -5°C increasing with duration of exposure from 1 h to 6 h. Mean fecundity was reduced significantly in aphids cooled at the adult stage, the number of aphids born per day decreasing as the exposure period of the cold-pulse increased, suggesting that low temperature had affected embryogenesis. All the nymphs born to adults surviving exposure to -5°C for 6 h died within 48 h of birth, indicating that low temperature has a pre-natal effect on mortality.     

肚倍蚜瘿内种群动态与虫瘿生长发育的关系

【目的】本研究拟对肚倍蚜Kaburagia rhusicola瘿内种群动态与虫瘿生长发育关系进行研究,为深入研究肚倍蚜的生物学特性奠定基础。【方法】在2014年4月27日至7月16日期间,在湖北竹山田间每间隔10 d随机选择长势基本一致的青麸杨,分别采集健康肚倍蚜虫瘿,每次采集样本30个。采用排水法测量虫瘿体积,之后将虫瘿解剖,取出瘿内蚜虫,置于培养皿内,采用四分法统计数量。对虫瘿体积增长与瘿内蚜虫种群变化进行了相关性分析。【结果】虫瘿体积增长与蚜虫种群数量增长之间呈极显著正相关(r=0.960,P0.01)。虫瘿体积与蚜虫种群数量增长分别呈现3个峰,即5月6日至5月16日、5月26日至6月6日和6月26日至7月6日。肚倍蚜瘿内密度变化的主要趋势是先降后升,中间有一个小的起伏。【结论】本研究表明虫瘿大小和瘿内蚜虫种群数量有关,虫瘿体积可用于评价干母的环境适合度。     

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.     

微波辐射对桃蚜生长发育和繁殖的影响

【目的】研究筛选对桃蚜Myzus persicae有致死作用的安全微波频率和照射时长,以为探究新型物理防蚜技术,弥补化学防治上的缺陷提供参考依据。【方法】在暗箱中,应用微波发射仪分别发射1375, 2 750, 5 500和11 000 MHz 4个不同频率的微波照射桃蚜1日龄无翅成蚜,每个频率的照射时长分别为15, 30, 60和120 s;照射后在人工气候箱中饲养,分别于照射后8, 24, 48和72 h观察其生长发育及繁殖状况,统计桃蚜死亡率、繁殖力(累计产蚜量)及子代有翅蚜率。【结果】4个不同频率的微波分别在4个不同照射时长下,对桃蚜1日龄无翅成蚜的死亡率、繁殖力和子代翅型分化都有不同程度的影响。照射后72 h, 5 500 MHz微波照射时间为15 s时对桃蚜1日龄无翅成蚜的致死作用最强,死亡率达到55.00%,在照射时间为30和120 s时可抑制子代桃蚜向有翅蚜的分化。2 750 MHz微波照射30和60 s时促进桃蚜1日龄成蚜繁殖,照射30 s时繁殖力最强,而照射15和120 s时却表现为抑制繁殖,且2 750 MHz微波照射30 s能抑制子代桃蚜向有翅蚜分化。【结论】微波辐射能够影响桃蚜1日龄成蚜的存活、繁殖和子代翅型分化。本研究初步筛选出了对桃蚜1日龄无翅成蚜有致死作用的微波频率和照射时长。     

不同类型品种棉花上棉蚜适生性及种群动态

通过田间调查、室内网罩盆栽苗测定选择性等方法,考察了常规棉（泗棉3号,石远321）、杂交抗虫棉（辽棉19号,鲁棉研18号）、转单价基因抗虫棉（国抗12号,中棉所32）和转双价抗虫棉（SGK321,中棉所41）4种类型8个品种棉花上棉蚜的适生性及种群动态。结果表明： 棉蚜在各棉花品种上的种群动态有明显差异（P<0.05）,单株蚜量以转单价基因抗虫棉中棉32上最高,常规棉泗棉3号上最低,分别为297.81头/株和76.88头/株。棉蚜对4种类型棉花品种的选择性有明显差异（P<0.05）,其中对转单价基因抗虫棉有很强的选择性。根据棉蚜实验种群的参数判断,其在不同品种棉花上的生长发育、存活及繁殖存在显著差异： 若虫发育历期常规棉石远321上最长（6.46天）,双价棉中棉所41上最短（5.75天）; 存活率转单价基因抗虫棉中棉32上最高（88.21%）,双价棉SGK321上最低（76.46%）; 单雌产蚜量杂交抗虫棉辽棉19上最大（44.48头）,双价棉SGK321上最小（33.51头）; 内禀增长率转单价基因抗虫棉中棉32上最高（0.3695）,双价棉中棉所41上最低（0.3389）。综合评价,棉蚜的生存和繁殖适合性在转单价基因抗虫棉上最高,在双价棉上最低。     

Effect of soil potassium availability on soybean aphid (Hemiptera: Aphididae) population dynamics and soybean yield

Studies were conducted to examine the effect of potassium (K) on soybean aphid, Aphis glycines Matsumura, population growth. A laboratory feeding assay examined the effect of K-deficient foliage on life table parameters of soybean aphids, and field experiments were designed to determine the effect of three soil K treatment levels on aphid populations and their impact on soybean yields. The feeding assay found that life table parameters differed between aphids feeding on the K-deficient and nondeficient soybean leaves. Soybean aphids in the K-deficient treatment exhibited significantly greater intrinsic rate of increase (r(m)), finite rate of increase (lambda), and net reproductive rate (Ro) relative to aphids feeding on nondeficient leaves. No significant difference was observed in mean generation time (T) between the two treatments. However, the field experiment repeated over 2 yr showed no effect of K on soybean aphid populations. Soybean aphid populations were high in unsprayed plots and feeding resulted in significant yield losses in 2002 at all three K treatment levels: when averaged across 2001 and 2002, unsprayed treatments yielded 22, 18, and 19.5% less than the sprayed plots in the low, medium, and high K treatments, respectively. No significant interaction was observed between aphid abundance and K level on soybean yields in either year. This study therefore suggests that although aphids can perform better on K-deficient plants, aphid abundance in the field may be dependent on additional factors, such as dispersal, that may affect final densities within plots.     

仲夏棉蚜种群崩溃机制研究进展

棉蚜是世界性分布的棉花害虫,仲夏棉蚜种群崩溃是生态控制棉蚜危害的重要途径,为棉蚜预测和防治提供了新思路与切入点,但其崩溃机制尚未明确。导致棉蚜种群崩溃的可能因素主要包括:(1)植物次生代谢物影响棉蚜的发育和繁殖,但不足以导致棉蚜种群崩溃;(2)暴风雨对棉蚜种群有一定的影响,但无法解释连续多年和多个地点发生的种群崩溃现象;(3)高温显著降低棉蚜的存活和繁殖,且与仲夏棉蚜种群崩溃期相吻合,高温很可能是棉蚜种群崩溃的关键影响因子;(4)高密度条件下激烈的种内竞争导致棉蚜繁殖率降低,有翅蚜比例增加;(5)天敌除具有直接捕食或寄生作用外,同时间接影响若蚜生长发育和刺激有翅蚜形成,对棉蚜种群后期崩溃发挥重要作用。本文对可能导致仲夏棉蚜种群崩溃的主要因素分别进行论述,探讨其对棉蚜存活、繁殖和有翅蚜形成的影响,旨在为探明仲夏棉蚜种群崩溃机制提供参考。     

温度对巨膜长蝽生长发育与繁殖的影响

【目的】近年来巨膜长蝽Jakowleffia setulosa (Jakovlev)由稳定种群的荒漠昆虫上升为暴发性发生并迁移至农区危害的农业害虫。由于缺乏巨膜长蝽生物学基础研究,给监测预警及综合防治带来许多困难。本研究旨在探明温度对巨膜长蝽发育和繁殖的影响。【方法】本实验以白茎盐生草Halogeton arachnoideus Moq.为寄主植物,分别在7个恒温（13,18,23,28,33,35和37℃）下研究了温度对巨膜长蝽各虫态平均发育历期、发育速率、成活率、产卵量和种群参数的影响。【结果】在13~37℃范围内,各虫态的发育历期随温度的升高而缩短,13℃完成一个世代发育需要82.63 d,37℃只需要14.61 d。各虫态的发育速率（V）与温度（T）的关系均符合多项式回归模型,且极显著相关。采用直接最优法分析,巨膜长蝽世代的发育起点温度为8.30℃,有效积温为555.77日·度,在宁夏一年可发生2代。巨膜长蝽世代存活率均在33℃时最高,为35.44%。28～37℃之间单雌产卵量较多,达到10粒以上,通过方程拟合得到理论上雌虫产卵最适温度为34.59℃,产卵量最高可达到16.73粒/雌;种群趋势指数在13℃为零,18～23℃小于1,种群呈负增长;28～37℃大于1,且33℃时最高,为2.77;净增殖率、内禀增长率及周限增长率均在37℃时最高,分别为7.24, 0.3912和1.4787;种群世代周期以13℃时最长,为45.8936 d,37℃时最短,为5.0608。【结论】巨膜长蝽在28～35℃下存活率、增长指数和繁殖力较高,说明该温度范围是巨膜长蝽生长发育和繁殖的适宜温度。本研究为有效开展巨膜长蝽的监测预报及综合防控提供了科学依据。     

Effect of vermicompost and cucumber cultivar on population growth attributes of the melon aphid (Hemiptera: Aphididae)

Worldwide, the developing industry of cucumbers (Cucumis sativus L.) grown in greenhouses is threatened by damage from sucking pests, especially aphids. Among these, the melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), is the most serious. We tested the effect of two cucumber cultivars ('Royal' and'Storm') and three vermicompost concentrations (0 [control], 20, and 30%) in field soil on the development and fecundity rates of A. gossypii, by using a randomized complete block design with four replicates as a factorial experiment. The developmental times of nymphs reared on plants grown into the three vermicompost concentrations ranged from 5.5 (0%) to 8.7 (30%) d (on Storm) and from 4.3 (0%) to 7 (30%) d (on Royal). The developmental time of melon aphid's nymphs was greatest on plants grown in the culture medium with 30% vermicompost rate and least on plants reared in the soil without vermicompost. The intrinsic rate of natural increase (r,,) of A. gossypii ranged from 0.204 d(-1) on plants grown in the soil amended with 30% vermicompost rate (on Storm seedlings) to 0.458 d(-1) on plants grown in the soil without vermicompost (on Royal seedlings). Accordingly, our findings confirm that a combination of a low level of vermicompost and a partially resistant cucumber cultivar might play an important role in managing this aphid on cucumbers in greenhouses.     

Population dynamics of the whitebacked planthopper,Sogatella furcifera (Hemiptera: Delphacidae) with special reference to the relationship between its population growth and the growth stage of rice plants

A population census was conducted to describe the effects of the growth stage of rice on the population dynamics ofS. furcifera, in particular, on immigration, seasonal abundance, population growth rate, and wing-form expression. The number of immigrants was highest on rice plants 17 to 30 days after transplanting (DAT), which suggested that immigrants prefer to settle or remain more on rice plants at the tillering stage (approximately 20–30 DAT). Population growth rate from immigration to the 1st generation decreased with an increase in rice plant age. In contrast, population growth rate from the 1st to 2nd generation was not influenced by rice plant age and was negatively density-dependent. The percentage of macropters (flyers) was positively related to the growth stage of rice when rice was in the vegetative or early part of the reproductive stage, and reached 100% at about 10 days before heading (booting stage). Threafter, most adult females molted into macropters regardless of population density. The roles of host plant age and crowding effect on the population dynamics ofS. furcifera are discussed.     

Relationship between susceptibility to neonicotinoids and population dynamics of cotton aphid,Aphis gossypii Glover (Hemiptera: Aphididae)

Efficiency of imidacloprid and thiametoxam on population growth parameters of Aphis gossypii Glover (Hemiptera: Aphididae) was assessed using three bioassay methods including; residual, starvation and FAO dip methods. Aphids were assayed under laboratory conditions at 23 ± 2°C, photoperiod of 16:8 (L:D) and 70% relative humidity. Aphids were transferred to sprayed leaves and Petri dishes in residual and starvation methods, respectively. There was no feeding for the aphids in starvation method. In FAO dip method, insects were dipped for 5 s in pesticide solutions and then transferred to fresh leaves. Results revealed that LC₅₀ values calculated with the starvation and residual methods were respectively 15 and 11% more than FAO dip method (for imidacloprid) and 22 and 18% (for thiametoxam). The LC₅₀ value in starvation method was 3% more than the residual method. Calculated LC₅₀ in starvation and residual methods with imidacloprid respectively caused 160 and 34% increase in intrinsic rates of increase (r _m) and net reproductive rate (R ₀) in comparison with FAO dip method. Generation time (T) and doubling time (DT) were respectively 59 and 62% less than those in FAO dip method. In contrast, thiametoxam (LC₅₀ concentration) in starvation and residual method lead to 9 and 67% increase in r _m and R ₀ parameters compared to FAO dip method. However T and DT were respectively 65 and 92% less than mentioned parameters in FAO dip method. There was not any significant difference between life table parameters calculated by residual and starvation bioassay methods.     

Effects of temperature on the life history parameters and population growth rates of Hyalopterus pruni (Hemiptera: Aphididae)

The mealy plum aphid, Hyalopterus pruni (Geoffroy) (Hemiptera: Aphididae) is a pest of prune trees in California. The impact of aphids as pests is well characterized by their population growth rate, a parameter integrating their age-specific development, survivorship, and fecundity. These population parameters were measured at five constants temperatures on potted prune trees. Development rates increased with temperature up to an optimum. The relationship between development rate and temperature was described by linear and nonlinear models. Developmental threshold temperature was greater for the nonlinear model than for the linear model. Thermal requirement for development and maximum lethal temperature determined by these models were similar to those for other aphids. The greatest proportional survivorship of nymphs occurred at 26 degrees C. Mean daily fecundity was lowest at 14 degrees C and highest at 22 degrees C. Adult longevity decreased with temperature. Population growth rates for H. pruni were estimated from measurements of fecundity and development time and were highest at 22 degrees C. This is the first study to document the temperature dependence of the life history parameters for H. pruni and the first to generate a degree-day model for the prediction of phenological events.     

Systemic control efficacy of neonicotinoids seeds dressing on English grain aphid (Hemiptera: Aphididae)

English grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae), is an important pest of wheat (Triticum aestivum L.), and is usually controlled by intensive foliar sprays of pesticides under field conditions. In order to reduce labour costs and increase the utilization of pesticides, neonicotinoids seed treatment was studied as a simple and accurate control technology for S. avenae. We evaluated the mortality of imidacloprid, acetamiprid, thiamethoxam, clothianidin, nitenpyram and dinotefuran to the English grain aphid by seed dressing methods in the laboratory, and found that the toxicity with that LC₅₀ of clothianidin (20.97?a.i.?g/100?kg seeds) and thiamethoxam (28.84?a.i.?g/100?kg seeds) to S. avenae are higher than other neonicotinoids. LC₅₀ values of nitenpyram, imidacloprid and acetamiprid ranged between 120?a.i.?g/100?kg seeds and 210?a.i.?g/100?kg seeds. Dinotefuran showed the lowest toxicity with LC₅₀ value 565.76?a.i.?g/100?kg seeds to English grain aphid. Field plot experiments were conducted to investigate the control efficacy of neonicotinoids seed treatment for the aphid, and the effects on growth of wheat. Field observations indicated that clothianidin and thiamethoxam provided the better control efficacy on the English grain aphid than imidacloprid, and had no influence on wheat seedling emergence. These results showed that seed treatment by neonicotinoids was effective against S. avenae throughout the growth period, furthermore, thiamethoxam and clothianidin were the effective and safe alternative options for S. avenae management in the crop.