甘薯小象虫发生原因分析及综合治理技术

甘薯小象虫是莆田市甘薯最主要害虫,近年来发生为害日趋严重.本文分析了甘薯小象虫在我市严重发生原因和为害特点,并提出以农业防治为主,辅以生物、药剂防治等的综合治理技术和办法,提供生产上参考应用.     

甘薯麦蛾性引诱试验初报

甘薯麦蛾 Brachmia triannuella Herrich-Schaffer又叫甘薯卷叶虫,是食害甘薯叶子的主要害虫。发生普遍,为害严重,对甘薯生产威胁很大。昆虫性外激素的利用是害虫测报与防治的新途径之一。现把1977年对此虫进行性引诱试验的结果整理于下。     

甘薯品种营养成份与抗小象虫的相关性研究

通过田间和网室测定结果,抗小象虫较好的甘薯品种有抗虫1号、台农26、Tis2534、Ricin和鸡蛋黄;抗小象虫较弱的品种有新种花、惠红早、“329”、广薯15等。甘薯品种的营养成份与抗小象虫相关性分析结果表明,抗、感品种与粗纤维、粗脂肪含量无明显相关,与粗淀粉有显负相关,R1=-0．9935,而与粗蛋白和18种氨基酸总量有显正相关,R2=0．9741,R3=0．9621。表现粗淀粉含量高的品种,其虫害指敦较低,抗虫性强;而粗蛋白含量和18种氨基酸总量高的品种,其虫害指数较高,抗虫性则表现较弱。测定分析说明了甘薯品种营养成份与抗虫性存在一定的相关性。     

甘薯天蛾的初步研究

甘薯天蛾即旋花天蛾(Herse convolvuli Linn-aeus)以在在安徽很少发生,1961年以来,宿县、阜阳两地区为害趋向严重,是甘薯生产上需要解决的问题。 为了摸清发生规律和防治方法,1962—1965年在五河县进行了系统观察和研究,近年来又作了补充调查,现汇总整理如下。     

福建省甘薯象虫发生和防治

甘薯象虫(Cylas formicarius Fabricius)俗名甘薯小象鼻虫,是我国东南各省的主要害虫之一。在福建有记录发生的达四十六个县市,其中尤以沿海各县市发生普遍,为害严重。甘薯受害后不仅块根不能生长,而且变质有苦臭味,不宜食用,造成极大损失。本省历     

旋花天蛾初步观察

旋花天蛾(Herse convolvuli L.)又名甘薯叶天蛾,群众叫它“花豆虫”,是我区甘薯上的重要害虫。我们进行了发生规律的观察,现将几年来的结果整理如下。 一、生活习性 1.生活史及各虫态历期 旋花天蛾在阜阳地区一年发生3—4代,以蛹在土中越冬。1964年黑光灯下出现了明显的四个高峰,初步认为该年发生不完全的4代(表1)。越冬蛹于5月中旬开始羽化,6月上旬羽化最多,6月中、下旬幼虫为害春甘薯,第一代成虫在7月中旬盛发,主要产卵于春甘薯,少数产在旱插的夏甘薯(即麦茬甘薯)上,7月中、下旬为幼虫为害时期,第二代成虫8月上旬盛发,8月中、下旬幼虫严重为害春、夏甘薯,第三代成虫于9月上旬盛发,9月中、下旬又进入暴食为害。从近几年观察来看,旋花天蛾在我区主要以8、9月为害最重,个别年份,7月份也能在局部地区发生为害。     

甘薯抗黑斑病种质资源的研究及育种利用

甘薯黑斑病(black rot)是危害甘薯严重且普遍发生的病害,生产上主要采用综合防治方法进行防治,其中选育抗病性品种是防治甘薯黑斑病最经济、有效的措施。长期以来人们围绕甘薯抗黑斑病种质资源进行了多方面研究,本文系统地概述了甘薯抗黑斑病种质资源鉴定、筛选,以及甘薯对黑斑病的抗性遗传特点和抗黑斑病种质资源的育种利用,并展望了甘薯抗黑斑病资源与育种的研究前景。     

稀点雪灯蛾的生物学及防治

<正> 稀点雪灯蛾Spilosoma urticae(Esper)属鳞翅目,灯蛾科。我省过去很少发生,近年来,为害麦田套播玉米幼苗日趋严重。我们经过三年室内饲养和田间调查,已摸清其生物学特性、发生规律及防治方法,现将研究结果总结如下。 一、为害及分布 稀点雪灯蛾是一种杂食性害虫,为害玉米、豆类、棉花、甘薯、蓖麻、芝麻、向日葵、麻类、瓜类、小麦、高梁、谷子、黍子、苜蓿、白菜、辣椒、茄子、西红柿及桃、李、柳、榆、泡桐、紫穗槐等。稀点雪灯蛾以第1代幼虫为害麦田套播玉米幼苗最盛,可将幼苗全部吃光,造成缺苗断垄,甚至     

广州甘薯象虫的初步观察及防治意见

甘薯象虫(Cylas formicarius Fabricius)又名甘薯象鼻虫或甘薯小象鼻虫,属鞘翅目、象虫科,是一种检疫性害虫,也是我国南方甘薯产区里一种重要甘薯害虫。它在广州发生甚多,容易猖獗为害,被列为急待解决的一个虫害问题。 我们于1955年9月间在广州开始进行此虫的调查观察,并着手作小规模的药剂杀除试验,     

烦夜蛾生活习性的研究

<正> 烦夜蛾Anophia leucomelas Linnaeus分布于广东、四川、福建。在福建沿海甘薯产区,近年来发生普遍,为害严重,已成为甘薯生产上的主要害虫之一。作者于1978年以来对此虫进行了研究,现将结果整理介绍于下。     

Biological control of Salvinia molesta in some areas of Moremi Game Reserve,Botswana

The Curculionid weevil, Cyrtobagous salviniae Calder & Sands, has been established on Salvinia molesta (salvinia) in Botswana. The study determined the intensity of weevil activity on the weed at the margin and the centre of four selected sites on the Khwai system of the Okavango Delta. Random samples of salvinia were collected from each site at monthly intervals in 1998 to extract weevils and to demonstrate the effect of weevil on the weed. The rate at which the weed was controlled at different sites varied with mat and weevil density. The biological control at Paradise Pools was moderate without much increase in the weed biomass per m², while fluctuations in both weevil and plant populations were noticed in the Khwai streams. Weevil numbers remained low at Dombo for the first nine months of the year, during which time the mat density increased. With the onset of higher temperatures, weevil numbers increased to 155 and 457/kg fresh weight of salvinia at the margin and centre respectively in Dombo Pool in early summer. A significant control in MGR 6 HATAB pool between mat biomass and the weevil number resulted in the disappearance of the weed in three months. This study shows that C. salviniae is an effective biological control agent of S. molesta in semiarid areas.     

Impact of different densities of Neohydronomus affinis (Coleoptera:Curculionidae) on Pistia stratiotes (Araceae) under laboratory conditions

In Senegal, a laboratory study was conducted in 2005 to ascertain the effect that different numbers of the host-specific weevil Neohydronomus affinis Hustache (Coleoptera: Curculionidae) per plant had on selected plant growth parameters of its target weed, water lettuce Pistia stratiotes Linnaeus (Araceae). Compared to the control, the weevil caused a significant reduction in all parameters measured, except for daughter plant production. There were no significant differences in impact on the plant between the three different densities of weevil (one, two and three pairs per plant). Under laboratory conditions one pair per plant is deemed sufficient to effect complete control of water lettuce over a six-week period.     

Proactive spraying against boll weevils (Coleoptera: Curculionidae) reduces insecticide applications and increases cotton yield and economic return

The current standard practice of two to three preemptive insecticide applications at the start of pinhead (1-2-mm-diameter) squaring followed by threshold-triggered (whenever 10% of randomly selected squares have oviposition punctures) insecticide applications for boll weevil, Anthonomus grandis grandis Boheman, control does not provide a reliably positive impact on cotton, Gossypium hirsutum L., yields in subtropical conditions. This study showed that four fewer spray applications in a "proactive" approach, where spraying began at the start of large (5.5- 8-mm-diameter) square formation and continued at 7- to 8-d intervals while large squares were abundant, resulted in fewer infested squares and 46-56% more yield than the standard treatment at two locations during 2004. The combination of fewer sprays and increased yield made the proactive approach 115-130% more profitable than the standard. The proactive approach entails protection only at the crop's most vulnerable stage (large squares) that, as a source of food, accelerates boll weevil reproduction. In contrast, the standard approach protects early season small squares and later season bolls, both of which contribute less to boll weevil reproduction than large squares. Proaction is an in-season crop protection approach that can be used to increase yield in individual fields during the same season and that could be incorporated into boll weevil eradication strategy that involves later diapause sprays. Because proaction is based on an important relationship between the cotton plant and boll weevil reproduction, the tactic will probably be effective regardless of climate or region.     

Field parasitism of nontarget weevil species (Coleoptera: Curculionidae) by the introduced biological control agent Microctonus aethiopoides Loan (Hymenoptera: Braconidae) over an altitude gradient

The parasitoid, Microctonus aethiopoides Loan (Hymenoptera: Braconidae) was introduced into New Zealand in 1982 to control the alfalfa pest, Sitona discoideus Gyllenhal (Coleoptera: Curculionidae). Studies have shown that a number of nontarget weevil species are attacked in the field by this parasitoid. A field study was carried out to investigate nontarget parasitism by M. aethiopoides over an altitudinal sequence from the target host habitat (alfalfa) into native grassland. Three locations were selected for the study, and at each, the alfalfa growing in the valley floor was sampled annually for parasitism of the target pest that ranged between 17 and 78%. At progressively higher altitudes, three further grassland sites at each location were sampled monthly during spring to autumn for up to 6 yr. Weevil densities were estimated, species identified, and dissections carried out to determine reproductive status and parasitism. Almost 12,000 weevils were collected during the study, which were identified as 36 species in total from the three locations. Eight weevil species were found to be parasitized, including S. discoideus, the target host that was found at all sites. Parasitism of nontarget species was approximately 2% overall but varied with location, site, and season. Substantial nontarget parasitism was found at only one of the locations, with up to 24% parasitism of a native weevil, Nicaeana fraudator Broun (Coleoptera: Curculionidae), recorded. Another species, Irenimus egens (Broun) (Coleoptera: Curculionidae), was also found at this location at similar population densities but was attacked far less by M. aethiopoides. Results are discussed in relation to weevil phenology.     

Employing in vitro directed molecular evolution for the selection of α-amylase variant inhibitors with activity toward cotton boll weevil enzyme

Numerous species of insect pests attack cotton plants, out of which the cotton boll weevil (Anthonomus grandis) is the main insect in Brazil and must be controlled to avert large economic losses. Like other insect pests, A. grandis secretes a high level of α-amylases in the midgut lumen, which are required for digestion of carbohydrates. Thus, α-amylase inhibitors (α-AIs) represent a powerful tool to apply in the control of insect pests. Here, we applied DNA shuffling and phage display techniques and obtained a combinatorial library containing 10⁸α-AI variant forms. From this library, variants were selected exhibiting in vitro affinity for cotton boll weevil α-amylases. Twenty-six variant sequences were cloned into plant expression vectors and expressed in Arabidopsis thaliana. Transformed plant extracts were assayed in vitro to select specific and potent α-amylase inhibitors against boll weevil amylases. While the wild type inhibitors, used to create the shuffled library, did not inhibit the A. grandis α-amylases, three α-AI mutants, named α-AIC3, α-AIA11 and α-AIG4 revealed high inhibitory activities against A. grandis α-amylases in an in vitro assay. In summary, data reported here shown the potential biotechnology of new α-AI variant genes for cotton boll weevil control.     

Killing power of the red imported fire ant [Hym.: Formicidae]: a key predator of the boll weevil [Col.: Curculionidae]

The red imported fire ant,Solenopsis invicta Buren, was identified as a key predator of the boll weevil,Anthonomus grandis Boheman. Although key factor analysis does not guarantee that the key factor is the causative agent, the evidence of boll weevil mortality was so clear that the fire ant could be identified as causing the mortality. Ant predation on immature boll weevils during the summer of 1981 averaged 84%. When this predation was combined with other natural mortality factors, the weevil population density throughout the season never exceeded levels that required control measures.     

Comparative susceptibility of sweetpotato weevil (Coleoptera: Brentidae) to selected insecticides

The response of sweetpotato weevil, Cylas formicarius (F.) (Coleoptera: Brentidae), to insecticides used for its control was tested in laboratory bioassays. A glass vial bioassay technique was used to determine the susceptibility of two cohorts of sweetpotato weevil to selected insecticides. Vials were treated with methyl parathion, bifenthrin, cyfluthrin, carbaryl, and phosmet. Sweetpotato weevils demonstrated a mortality response to increasing concentrations of all insecticides tested, and our results indicated decreases in susceptibility of the Louisiana cohort of sweetpotato weevil compared with the Texas cohort for all insecticides tested. Methyl parathion was the most toxic chemical tested for both cohorts, followed by the pyrethroids, cyfluthrin and bifenthrin. Phosmet exhibited moderate toxicity compared with other chemicals tested, whereas sweetpotato weevils were least susceptible to carbaryl. Significant differences in lethal concentration (LC)50 and LC90 values for cyfluthrin and bifenthrin, the LC50 values for methyl parathion and phosmet, and the LC90 values for carbaryl were observed between the two cohorts. This study documents baseline toxicological data for five insecticides in two populations of sweetpotato weevil and demonstrates that susceptibility to all insecticides tested is lower for the Louisiana population compared with the Texas population.     

Long-term Assessment of the Biological Control of Sitona discoideus by Microctonus aethiopoides and Test of a Model

Autumn densities of the pest weevil Sitona discoideus and its braconid parasitoid Microctonus aethiopoides were monitored from 1996 to 1998 on the Canterbury Plains, New Zealand. M. aethiopoides was introduced as a biological control agent in 1982 and first appeared in the study area in 1986. By 1991 around 50% of autumn weevils were parasitized and weevil density had been reduced by 75%. A model for the system at that time suggested that this level of suppression would be sustained. In agreement with the model, the recent survey confirmed that successful biological control had been maintained, with 75% suppression of weevil density but slightly lower rates of parasitism of around 35%. Weevil densities showed a significant trend longitudinally across the area surveyed, increasing from east to west, probably reflecting soil type. Weevil sex ratio was significantly biased towards females, yet the proportion of males that were parasitized was twice that of females. Percent parasitism in autumn related positively to weevil density over time and space. The scale of homogeneity, and by implication effective annual dispersal, is estimated at 12 +/- 4 km radius for weevils.     

From Augmentation to Conservation of Entomopathogenic Nematodes: Trophic Cascades, Habitat Manipulation and Enhanced Biological Control of Diaprepes abbreviatus Root Weevils in Florida Citrus Groves

The use of entomopathogenic nematodes (EPN) for management of the root weevil, Diaprepes abbreviatus, in Florida citrus groves is considered a biological control success story and typically involves augmentation in which EPN are applied inundatively as biopesticides to quickly kill the pest. However, recent evidence indicates that efficacy of EPN applications in Florida citrus depends on soil type. They are very effective in the well drained coarse sands of the Central Ridge but often less so in poorly drained fine-textured soils of the Flatwoods. Moreover, groves on the Central Ridge can harbor rich communities of endemic EPN that might often suppress weevil populations below economic thresholds, whereas Flatwoods groves tend to have few endemic EPN and frequent weevil problems. Current research is examining the ecological dynamics of EPN in Florida citrus groves, the potential impact of EPN augmentation on soil food webs, especially endemic EPN, and whether habitat manipulation and inoculation strategies might be effective for conserving and enhancing EPN communities to achieve long-term control in problem areas. Conservation biological control could extend the usefulness of EPN in Florida citrus and be especially appropriate for groves with persistent weevil problems.