Spatial dispersion and binomial sequential sampling for the potato psyllid (Hemiptera: Triozidae) on potato

BACKGROUND: The potato psyllid is a serious pest of potatoes. Sampling plans on potatoes for the potato psyllid have yet to be developed, thus the authors' objectives were (1) to determine the most efficient within‐plant sampling unit, (2) to determine the spatial dispersion of potato psyllids in potato fields and (3) to develop a binomial sequential sampling plan for this pest. RESULTS: Significantly more potato plants were infested with potato psyllids on the edges of the field, and significantly more plants were infested with psyllids on the ‘top’ and ‘middle’ of the potato plant. Significantly more psyllids were also found on the undersides of leaves. The potato psyllid has an aggregated distribution in potato fields. Binomial sequential sampling plans were developed for three action thresholds representing 0.5, 1 and 5 psyllids per plant. The average sample numbers for these action thresholds were between 12 and 16 samples, depending on the action thresholds. However, based on the shape of the operating characteristic curve, the 0.5 and 1 sampling plans were more reliable than the 5 psyllids per plant plan. CONCLUSION: The binomial sequential sampling plans are useful for detecting potato psyllids at low levels of infestation, which will be useful for pest management purposes. Copyright © 2011 Society of Chemical Industry     

Some Observations on the Basic Principles Involved in Ultra-low-volume Spray Application

Abstract

Between 1982 and 1985, Nigerian cassava fields were periodically sampled through three crop growing seasons to analyze the within and between‐plant distribution of CM as affected by weather (dry and rainy season) using the mean crowding statistics and Taylor's power law. Enumerative and binomial sampling plans were developed which take into consideration the seasonal changes in the spatial distribution patterns of CM. The costs of the two procedures were compared to select the most cost‐efficient sampling plan.     

Reduced agent-area treatments (RAAT) for management of rangeland grasshoppers: Efficacy and economics under operational conditions

The Reduced Agent-Area Treatment (RAAT) approach involves applying low rates of insecticides in intermittent swaths to control grasshopper infestations in an effort to achieve a more economically and environmentally sound pest management strategy compared to traditional blanket applications at high rates. Operationalscale (>250 ha) insecticide tests on Wyoming rangeland grasshopper infestations (18-56 grasshoppers/m2) at two sites in 1997 revealed that carbaryl yielded 94% control as a blanket treatment (560 g/ha) and 81% control as a RAAT application (280 g/ha applied to 50% of the infested land). Malathion yielded 90% control as a blanket treatment (683 g/ha) and 91% control as an RAAT application (342 g/ha applied to 80% of the infested land), and fipronil (4 g/ha) yielded 98% control as a blanket treatment and 92% control when applied to 33% of the infested land. One year after treatment, the RAAT and blanket-treated plots had 2-4% (Pollet Ranch) of the densities in untreated plots. Economic analysis showed that the greatest benefit:cost ratio was obtained with the fipronil-RAAT method, followed by carbaryl-RAAT, malathion-RAAT, malathion-blanket, fipronil-blanket, carbaryl-blanket. The worst-case outcome of fipronil and carbaryl with a RAAT approach had a greater economic return than the best-case outcome of no treatment. Following blanket treatments, non-target arthropod abundance was highest in the fipronil plots, followed by carbaryl and malathion; arthropod biomass was higher in the carbaryl plots than fipronil and malathion. In RAAT plots, arthropods were generally less impacted than in the blanket plots, with the least reduction caused by fipronil and carbaryl. Thus, the RAAT tactic appears to be economically and environmentally superior to blanket treatments under large-scale, operational conditions.     

河北省坝上红松洼草原蝗虫群落结构与多样性调查

为明确不同分区治理下河北省坝上红松洼草原生态环境对蝗虫群落多样性的影响,采用样方法于2019-2020年在不同草原类型和不同功能分区对蝗虫群落进行调查,通过丰富度、个体数、多样性指数以及均匀度指数分析蝗虫的多样性,并对不同生态因子和蝗虫多样性指标进行相关性分析.结果 表明:该地区蝗虫发生种类共有5科8亚科14属25种,...     

Sampling plans for aphids and their parasitoids in blueberry fields in Argentina

Densities of aphids (Aphis gossypii and A. spiraecola) and mummified aphids at different phenological stages of a blueberry crop were estimated for the purpose of developing sampling plans. Our data set comprised 99 samples taken during the period 2006–2008 in four fields in Buenos Aires Province, Argentina. Estimation of population density based on the proportion of sample units infested by individuals was investigated. We also calculated the minimum number of sample units to estimate the density of individuals on buds and buds + flowers using enumerative sampling. The relative precision of both methods was compared. Moreover, an enumerative sequential sampling protocol was developed. The presence–absence sampling plan gave density estimates with large variances (as measured by confidence intervals and large standard errors). The aggregation of mummies was similar on buds and buds + flowers, so the required number of sample units for density estimates was the same. Relative precision of estimates was much lower for the presence–absence sampling than the enumerative sampling, even at intermediate densities. An enumerative sequential plan would be the most appropriate and useful method in management plans for aphids and mummified aphids in blueberries.     

锡林郭勒盟典型草原昆虫多样性分析

为典型草原害虫监测预警和生态治理提供理论依据,选取害虫发生相对严重的锡林郭勒盟7个旗县典型草原作为调查对象,采用Z字形扫网取样法对昆虫数量和种类进行调查,对昆虫尤其是主要昆虫蝗虫群落差异和多样性进行分析,并对蝗虫群落和环境因子进行冗余分析。结果显示,在7个典型草原区域中,正镶白旗、镶黄旗、阿巴嘎旗、西乌珠穆沁旗和锡林郭勒市的昆虫Margalef丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数均较高,且这5个草原区域之间均差异不显著;在7个典型草原区域内共采集到草原蝗虫6科11属16种,种类较丰富,约占所有昆虫种类的20.00%;亚洲小车蝗Oedaleus asiaticus作为锡林郭勒盟典型草原蝗虫的优势种,在所有典型草原区域中的数量均高于其他蝗虫;镶黄旗和锡林浩特市的蝗虫种数最多,均为14种,而苏尼特左旗的蝗虫种数最低,为8种;植被覆盖度和海拔对蝗虫Margalef丰富度指数、Shannon-Wiener多样性指数和Pielou均匀度指数有正影响。锡林浩特市与镶黄旗的蝗虫群落相异性最小,相异性系数为0,与其他5个典型草原区域的蝗虫群落相异性也较低,相异性系数...     

牧场蝗虫复合防治指标的研究

１９９２－１９９３年，作者对甘肃农垦宝瓶河牧场冬春季草声蝗虫优势种华北雏Ｃｈｏｒｔｈｉｐｐｕｓ ｂｒｕｎｎｅｕｓ ｈｕａｂｅｉｅｎｓｉｓ Ｘｉａ ｅｔ Ｊｉｎ、鼓翅皱膝蝗Ａｎｇａｒａｃｒｉｓ ｂａｒａｂｅｎｓｉｓ （Ｐａｌｌ）、青海痂Ｂｒｙ铮洌澹恚? ｍｉｒａｍａｅ ｍｉｒａｍａｅ Ｂ．－Ｂｉｅｎｋｏ对牧草造成的为害程度及混合为害时的防治指标，即复合防治指标进行了研究，建立了华北雏蝗密度与牧草损失     

Toxicity and tolerance of sesquiterpene lactones in the migratory grasshopper, Melanoplus sanguinipes (Acrididae)

Sesquiterpene lactones, natural constitutents of the Asteraceae, are toxic to the grasshopper, Melanoplus sanguinipes, when injected into the hemocoel at doses greater than 0.25 μmol/300 mg insect. Dose-dependent sublethal symptoms range from a slight reduction in normal locomotory ability to severe locomotory impairment or paralysis, leading to death. The symptoms appear to be irreversible. Of the four compounds subjected to dose-response testing, parthenin was the most toxic with and LD₅₀ in adult male grasshoppers of 0.55 μmol/insect. Structure-activity relationships for four of the six lactones tested indicate that compounds containing a cyclopentenone ring are equitoxic to males and females, whereas those lacking this functional group are approximately 4 × more toxic to males than females. In contrast to their sensitivity to injected lactones, adult male grasshoppers can tolerate ingestion or topical administration of up to 4 μmol of these compounds without any adverse effects. These results suggest that the integument and alimentary canal in this species provide effective barriers limiting the bioavailability of sesquiterpene lactones to the hemolymph in nature. Possible target sites and mechanisms-of-action for sesquiterpene lactones (once in the bloodstream) are discussed.     

粉红椋鸟鸟巢结构和迁离时间防治草原蝗虫效果分析

人工招引粉红椋鸟控制蝗害是一种生物防蝗的重要手段,鸟巢结构以及粉红椋鸟迁离时间均影响其对蝗虫的防治效果。本文通过调查新疆地区不同结构的鸟巢中粉红椋鸟数量及其对鸟巢利用率,并结合粉红椋鸟迁离时间分析其对蝗虫的防控能力。结果表明,在调查的16个蝗虫发生区内,不同结构鸟巢招引效果为砖巢 > 石巢 > 天然鸟巢,砖巢、石巢和天然鸟巢招引效果分别为74.8%、71.9%和66.5%。分析粉红椋鸟迁离时间对蝗虫种群密度影响,成鸟迁离前对蝗虫的防控效果平均达58.4%,幼鸟迁离前对蝗虫的防控效果为88.8%。本文为进一步利用粉红椋鸟防治草原蝗虫提供重要理论依据。     

高山草地蝗虫群落生物多样性和空间聚集强度对植物群落的响应

为明确高山草地蝗虫群落生物多样性和空间聚集强度变化及其对植物群落的响应,在位于甘肃省祁连山中段北坡的研究区调查温性草原、山地草甸和高寒草甸3类草地中的蝗虫种类和数量,对不同蝗虫群落进行生物多样性分析,并观察不同蝗虫种群的聚集程度.结果 显示,共捕获蝗虫15种,8月温性草原内蝗虫虫口密度最大,为8.17头/m2,且此时S...     

Canola oil as a kairomonal attractant of rangeland grasshoppers: An economical liquid bait for insecticide formulation

Laboratory experiments and field trials demonstrated that canola oil, which is rich in fatty acids that are kairomonal cues in cannibalism, is an effective attractant of rangeland grasshoppers and a suitable oil-based carrier for insecticides. Laboratory-based olfactory tests revealed a significant, positive chemotaxis of Melanoplus sanguinipes in response to canola oil and olive oil mixtures. Small-scale field tests made by airbrush applications of 5 ml of canola oil (equivalent to 500 l/ha) to centres of aluminium rings (0.1 m²     

草原蝗虫防治指标的研究

作者测定了4种蝗虫从孵化至成虫期的食量,把草原蝗虫划分为以红翅皱膝蝗、邱氏异爪蝗和狭翅雏蝗为代表的大、中、小三种食量类型,混合种群虫口密度(x)与其对牧草取食量(y)的模型为y=16.4732x。通过野外混合种群不同密度下对牧草产量损失的测定,回归式为(ŷ)=-20.8070+14.4143x±15.56(r=0.9993,F>F_0.01),两种方法计算的防治指标分别为21.7、26.2头/m²,其经济允许损失均为8.8%。大、中、小三种食料类型的防治指标分别为5.2、17.6和32.3头/m²。     

中国特色蝗灾治理技术体系及应用成效

中国有数千年蝗灾发生为害的历史,建国初期在政府的组织领导下,在科研人员和广大群众的努力下,提出并实施了“改治并举”的策略,改造东亚飞蝗发生基地近2/3,同时大规模使用化学农药进行防治,初步形成了以改造蝗虫发生基地为特色的蝗灾治理技术体系,经过长期实践,蝗灾得到有效遏制,保障了我国粮食生产安全和社会稳定,取得了世界瞩目的成绩。自20世纪80年代起,随着利用蝗虫微孢子虫Nosema locustae和绿僵菌Metarhizium spp.等微生物的治蝗技术获得突破性进展,我国已经形成了以生态控制（改造蝗虫发生基地）为基础,以生物防治为核心,以信息技术为辅助的具有中国特色的蝗灾治理技术体系,并走在国际前列。该技术体系的长期大规模应用,不但在有效防治蝗灾保障我国粮食安全生产、避免大规模使用化学农药造成环境污染和生态失衡等方面发挥了重大作用,而且也在支援国际蝗灾治理中做出了贡献。最后对未来蝗灾治理的关键问题和发展方向进行了探讨。     

Distribution pattern and sequential sampling plan for spotted pod borer,Maruca vitrata (Fabricius) (Lepidoptera: Crambidae) on pigeon pea,Cajanus cajan L

Spatial distribution of legume pod borer, Maruca vitrata (Fabricius) (Lepidoptera: Crambidae) on Pusa 992 pigeon pea cultivar during kharif (rainy season) 2011 and 2012 was analyzed through Taylor's power law (TPL) and Iwao's mean crowding (IMC) regression. M. vitrata exhibited an aggregated distribution pattern on the crop. The pooled data for the two years fitted well to the TPL (a = 1.05, b = 1.19, R² = 0.967) and the IMC (α = ?0.17, β = 1.124, R² = 0.99). The optimal sample sizes with the TPL parameters increased with an increased precision level. Based on the TPL parameters, the decision lines of sequential sampling for M. vitrata were determined to be d = 3n ± 2.5√n. The sequential sampling plan would economize decision-making for an effective management of M. vitrata.     

模糊聚类分析在沂蒙山区土蝗群落分区中的应用

自１９８９－１９９３年对沂蒙山区的土蝗进行了全面调查。明确了沂蒙山区土蝗群落的优势种群由笨蝗Ｈａｐｌｏｔｒｏｐｉｓ ｂｒｕｎｍｅｒｉａｎａ Ｓａｕｓｓ、中华稻蝗Ｏｘｙａ ｃｈｉｎｅｎｓｉｓ （Ｔｈｕｍｂ）、大垫尖翅蝗Ｅｐａｃｒｏｍｉｕｓ ｃｏｅｒｕｌｉｐｅｓ ９Ｉｖａｎ）、短额负蝗Ａｔｒａｃｔｏｍｏｒｐｈａ ｓｉｎｅｎｓｉｓ Ｂｏｌ、长翅黑背蝗Ｅｕｐｒｅｐｏｃｎｅｍｉｓ ｓｈｉｒａｋｉ ＢＯｌ、花     

Simulation studies of Senegalese Grasshopper ecosystem interactions II: the role of egg pod predators and birds

We present a simulation study of the role of birds and egg pod predators in the population dynamics of the Senegalese grasshopper. The model was an energetics-driven ecosystem model that included a natural Sahelian grass, millet, grasshoppers, the egg pod predators bombyliidae and Tenebrionidae, and 24 species of birds that prey on grasshopper nymphs and adults. The model simulated the rain-dependent dynamics and migration along a five-location south–north transect in Niger and Senegal, and the main outputs were the grasshopper pressure on the transect, measured as accumulated transect grasshopper days, and the density of eggs ready to emerge the following rainy season. The model was calibrated using observations from transects in Niger (2003, 2004) and Senegal (2004).

When input data from Niger 2003 and 2004 were applied, simulated reductions in grasshopper pressure during the rainy season from egg pod predators and birds, respectively, were within a range of 18–25%, but taken together the overall reduction in grasshopper pressure ranged between 35 and 37%. Using input from Senegal (2004) the birds accounted for reductions of around 25%.

When the impact of the natural enemies was measured in terms of reduction in the density of eggs hatching the following year, the simulated impact of the egg pod predators ranged between 45 and 83% and that of the birds between 33 and 39%, and the two groups combined caused reductions between 60 and 75%.

Analyses of the sensitivity to the bird species, added one by one, showed ‘predator saturation’ along the Niger transects (with low grasshopper density) but not along the Senegal transect.

For Niger, the sensitivity analyses revealed Cattle Egret, Grey-headed Sparrow, Chestnut-bellied Starling, Buffalo Weaver, Sudan Golden Sparrow, Grey Hornbill, Red-billed Hornbill and Abyssinian Roller to be the most important individual species. For Senegal the top-five individual bird species were Village Weaver, Buffalo Weaver, Savile's Bustard, Grey-headed Sparrow and Abyssinian Roller.     

放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制

为明确不同放牧模式对高山草地蝗虫群落生物多样性的影响及其作用机制,本研究调查牛放牧、羊放牧、牛羊混合放牧和休牧4种模式下高山草地植物群落特征、蝗虫群落组成和数量,分析蝗虫群落生物多样性特征,利用冗余分析方法分析植物群落与蝗虫群落的相关性,采用结构方程模型分析放牧模式对蝗虫群落的影响路径.结果 显示,与休牧相比,牛放牧、...     

The absorption of cypermethrin in the grasshopper Melanoplus sanguinipes (Fab.): Effects of volatilisation,temperature, age,sex and parasitisation by Malameba locustae (King and Taylor)

The residues from metered doses of cypermethrin were recovered from excised portions of grasshopper cuticle to determine losses by volatilisation. Residues from similar doses were also recovered from the cuticles of intact grasshoppers and from whole body homogenates after rinsing the cuticle, to determine rates of absorption and losses from metabolism. Residues were recovered from males and females one week and three weeks after fledging in grasshoppers infected with Malameba locustae and in uninfected ones. They were maintained at 15 or 30°C and sampled from each combination of factors at 4, 8, 16, 24, 30 and 48 h after treatment. There was no measurable loss of cypermethrin by volatilisation up to 72 h after application to excised portions of cuticle at either 15 or 30°C. In all combinations of factors, more cypermethrin was recovered externally (P <0.05) from grasshoppers held at 15°C than those held at 30°C and more from infected grasshoppers than from those that were uninfected. Significantly more cypermethrin was also recovered externally from males than from females (P <0.05) and more from infected one-week-old grasshoppers than those that were three weeks old. At 15°C there was a gradual trend towards accumulation of cypermethrin internally, but at 30°C an initial trend towards accumulation was followed by one of decline. Residual cypermethrin recovered could in general be related to the negative temperature coefficient of toxicity, to a decreased sensitivity to cypermethrin in infected grasshoppers and to an increased sensitivity in older grasshoppers.     

Sequential Sampling to Assess the Incidence of Infection by Monilinia vaccinii-corymbosi in Mechanically Harvested Rabbiteye Blueberry Fruit

ABSTRACT Blueberry fruit infected by Monilinia vaccinii-corymbosi, the causal agent of mummy berry disease, are unsuitable for use in processed food products. Fruit shipments that exceed a disease incidence threshold of 0.5% are redirected to alternative markets with substantial reductions in economic return to the producer. Because of this low tolerance, a sampling procedure with defined statistical properties is needed to determine disease incidence in the packinghouse. In this study, a sequential sampling plan was developed based on counts and dispersion patterns of infected fruit in 23 loads of mechanically harvested rabbiteye blueberries. Each load was sampled 20 to 100 times, with each sample containing 550 cm(3) of fruit. Various dispersion statistics (k of the negative binomial distribution, Lloyd' index of patchiness, and Iwao' b) were computed, all of which suggested aggregation of infected fruit. Because k was variable across loads, Iwao' regression procedure, which does not assume a single frequency distribution with fixed parameters describing the counts of infected fruit, was used to develop upper and lower stop lines for sequential sampling. For alpha = 0.05 and assuming a total of 250 fruit per 550-cm(3) sample, the resulting sampling plan would require only one sample to conclude that a load exceeds the threshold if the number of infected fruit in that sample is greater than four. A minimum of six samples would be needed to conclude that disease incidence in a load is below the threshold if the cumulative total of infected fruit in these samples is zero. Resampling analysis showed that most fruit loads could be classified reliably with <10 samples per load; for loads with a disease incidence very close to the 0.5% threshold, <50 samples were needed on average. Stop lines for sequential sampling for different fruit size classes are presented.     

Assessing regional scale weed distributions, with an Australian example using Nassella trichotoma

Knowledge of the spatial distribution of weed infestations over regional scales is essential for effective management of source populations and to assess future threats. To this end, the distributions of Nassella trichotoma across a study area in south‐east New South Wales, Australia, were analysed using the geographically local Getis–Ord G_i* spatial hotspot clustering statistic. The clustering of N. trichotoma observations was analysed at three infestation levels: presence (at any density), patch level and the occasional plant level. The results indicate that there are c. 578 km² of cells containing N. trichotoma in strongly clustered infestations, 11.2 km² within weakly clustered infestations distinct from the main clusters, and 55 km² that are not clustered. There are 117 km² of strongly clustered patch level cells, 3 km² in distinct but weak clusters, and none outside of a cluster area. Of the occasional plant level cells, 329 km² are strongly clustered, 6.2 km² are in distinct but weak clusters, and 19 km² are not clustered. These results provide a mechanism by which control efforts can be prioritized. The analysis approach described in this paper provides a consistent, quantitative and repeatable approach to assess weed infestations across regional scales and can be applied to any weed species for which spatial distribution data are available.