Planting transgenic insecticidal corn based on economic thresholds: consequences for integrated pest management and insect resistance management

A simulation model of the western corn rootworm, Diabrotica virgifera virgifera LeConte, was used to investigate whether sampling and economic thresholds can improve integrated pest management (IPM) and insect resistance management (IRM) when transgenic insecticidal crops are used for insect pest management. When transgenic corn killed at least 80% of susceptible larvae, the calculated economic threshold increased linearly as the proportion of susceptible beetles surviving the toxin increased. The use of economic thresholds slightly slowed the evolution of resistance to transgenic insecticidal crops. In areas with or without rotation-resistant western corn rootworm phenotypes, the use of sampling and economic thresholds generated similar returns compared with strategies of planting transgenic corn, Zea mays L., every season. Because transgenic crops are extremely effective, farmers may be inclined to plant transgenic crops every season rather than implementing costly and time-consuming sampling protocols.     

Using non-smooth models to determine thresholds for microbial pest management

Journal of Mathematical Biology - Releasing infectious pests could successfully control and eventually maintain the number of pests below a threshold level. To address this from a mathematical...     

正确理解和应用经济阈值

分析了害虫经济阈值制定与应用中的若干常见问题。制定问题主要来自试验和计算两方面。试验方面涉及虫量设置的梯度和范围、模拟为害、考察时间和供试虫龄以及样本大小等 ,计算方面涉及虫量计算、理论产量和防治效果等。阈值应用的问题涉及防治行动时间、多项投资选择、害虫自然存活率以及作物产量水平等。为避免这些陷阱 ,作者提出个人见解。     

几种农田作物害鼠经济阈值的测定

1 引言 农田害鼠的危害经济阈值是害鼠防治的依据,也是害鼠管理的一个重要指标,王华弟等及邢林等曾报道过这方面的研究,但未能考虑害鼠群落中各种鼠的数量组成比例和危害强度的不同,1983年,在山东     

A heat polyethylene glycol procedure as an alternative method for plasmafractionation

Polyethylenglycol 4000 was used in a combined process of fractionation at normal temperature for preparing gammaglobulin and albumin in a heat denaturation process. Albumin can be gained from human plasma with a high yield and purity by using a heat procedure at the presence of polyethylglycol 4000 and sodium octanate at 75 degrees C. The concentration of polyethylglycol 4000 varies during this heat procedures from 3-10% W/V.     

Fertility control using intrauterine devices: an alternative for population control in wild horses

The purpose of this study was to develop a contraceptive method for feral horses. The feral horse population has increased significantly in recent years despite attempts to control numbers. As in most wild animal population control programs, contraceptive methods must be easy to apply, cause minimal disruption to the social structure and be fully reversible. In the present study, we tested the effectiveness of an intrauterine device (IUD) for fertility control in mares. Six mares were fitted with a silastic O-ring-shaped IUD on July 1 of Year 1. The IUD-treated mares were turned out with 12 nontreated mares and a fertile stallion in a large pasture until October 20 (112 d). None of the IUD-treated mares and all the nontreated mares became pregnant. The IUD-treated mares were maintained separately from the stallion during the winter. Following removal of the IUD on April 27 of Year 2, the mares were again introduced to the pasture with the stallion together with 6 nontreated mares. For the 6 mares previously treated with an IUD, the mean interval from introduction to the stallion to conception was 17.5 +/- 5 d or 1.3 cycles per pregnancy, and all mares produced a normal foal at term. Subsequently, 19 recorded mare breeding seasons resulted in 18 foals. Uterine cytology and histopathology indicate that the IUD causes mild chronic endometritis without permanent changes in the endometrium. We conclude that based on our observations, the O-ring-shaped IUD is an effective, safe and practical contraceptive method for mares.     

Symbiotic microorganisms: untapped resources for insect pest control

Symbiotic microorganisms offer one route to meet the anticipated heightened demand for novel insect pest management strategies created by growing human populations and global climate change. Two approaches have particular potential: the disruption of microbial symbionts required by insect pests, and manipulation of microorganisms with major impacts on insect traits contributing to their pest status (e.g. capacity to vector diseases, natural enemy resistance). Specific research priorities addressed in this article include identification of molecular targets against which highly specific antagonists can be designed or discovered, and management strategies to manipulate the incidence and properties of facultative microorganisms that influence insect pest traits. Collaboration with practitioners in pest management will ensure that the research agenda is married to agricultural and public health needs.     

Bacterial symbiosis in Bactrocera oleae,an Achilles’ heel for its pest control

Investigations on microbial symbioses in Tephritidae have increased over the past 30 years owing to the potential use of these relationships in developing new control strategies for economically important fruit flies. Bactrocera oleae (Rossi)—the olive fruit fly—is a monophagous species strictly associated with the olive tree, and among all the tephritids, its symbionts are the most investigated. The bacterium Candidatus Erwinia dacicola is the major persistent resident endosymbiont in wild B. oleae populations. Its relationship with B. oleae has been investigated since being identified in 2005. This endosymbiont is vertically transmitted through generations from the female to the egg. It exists at every developmental stage, although it is more abundant in larvae and ovipositing females, and is necessary for both larvae and adults. Studying B. oleae–Ca. E. dacicola, or other B. oleae–microbe interactions, will allow us to develop modern biological control systems for area-wide olive protection and set an example for similar programs in other important food crops. This review summarizes the information available on tephritid–microbe interactions and investigates relationships among fruit flies, bacteria and host plants; however, its focus is on B. oleae and its strict association with Ca. E. dacicola to promote environmentally friendly control strategies for area-wide pest management.     

Purchasing for all: an alternative to fundholding.

OBJECTIVE--To evaluate general practitioner participation in a district health authority''s purchasing work. DESIGN--Questionnaire study of 131 Hackney general practitioners and 33 senior health service managers; review of the minutes of 28 meetings of the Hackney General Practitioners'' Forum and the contract between City and Hackney Health Authority and the St Bartholomew''s NHS Trust. SETTING--Hackney General Practitioners'' Forum. MAIN OUTCOME MEASURES--General practitioners'' and managers'' perceptions of how representative and effective the general practitioners'' forum is; proportion of new quality targets and service developments contributed by general practitioners; main issues discussed by the forum and impact on district health authority policy. RESULTS--99 (76%) general practitioners and 27 (82%) managers responded. Both groups perceived the forum as representative. 92% (24/26) of the managers thought the forum was effective but only 74% (70/95) of general practitioners did so, largely because some doubted that the forum was listened to 75% (103/138) of quality targets and 55% (16/29) of service developments planned in the 1993-4 contract were contributed by general practitioners. They also lobbied successfully for more resources for urology and community mental health services. CONCLUSIONS--Input into commissioning via a general practitioners'' forum can be both representative and effective. General practitioners need to work closely to achieve a consensus and those involved need administrative support. The relation between general practice and public health medicine needs to be strengthened.     

Zanamivir: an alternative translation.

This paper offers an alternative view to that given elsewhere regarding the value of zanamivir as an agent for treating patients who develop influenza symptoms. The position taken here has developed as a result of an analysis of the data that was undertaken by the journal Drug and Therapeutics Bulletin.     

Evaluation of action thresholds and spinosad for lepidopteran pest management in Minnesota cabbage

Action thresholds, based on the percentage of plants infested, for the lepidopteran pest complex in fresh-market cabbage Brassica oleracea variety capitata were evaluated in 1996 and 1997 in southern Minnesota. Three lepidopteran pests are common in Minnesota, including the imported cabbageworm, Pieris (=Artogeia) rapae (L.), diamondback moth, Plutella xylostella (L.), and the cabbage looper, Trichoplusia ni (Hübner). Most of the thresholds tested included all three pests. However, because T. ni is often the most consistent and damaging pest in Minnesota, two thresholds were based solely on the percentage of plants infested with T. ni eggs and larvae. Action thresholds were also evaluated for their compatibility with a recently labeled biologically based insecticide, spinosad, and a conventional pyrethroid, permethrin. Although all three lepidopteran pests were present in both years of the study, P. rapae provided most of the pest pressure in 1996, and T. ni was most abundant in 1997. Compared with the 0% larval infestation treatment (approximately weekly sprays from early heading to harvest), all action thresholds resulted in less insecticide use (17- 80%), while maintaining high levels of marketability. Despite variable pest pressure between years, one of the thresholds based solely on T. ni (10% of plants infested with eggs or larvae) performed as well as each of the thresholds based on all three species combined. For both years, and compared with a weekly spray schedule from early heading to harvest (average of 5.5 sprays per year), use of the 10% T. ni egg or larval threshold resulted in an average of 36.5% (3.5 sprays) and 65% (2.0 sprays) fewer applications of spinosad and permethrin, respectively, with no significant loss in marketability. The results indicate that a variety of incidence-based action thresholds can be used to ensure the production of high-quality cabbage in the midwestern United States with only minimal applications of spinosad or permethrin.     

RNAi technology: a new platform for crop pest control

The insect pests are big threat in meeting the food demands for future generation. The present pest control strategies, including the existing transgenic approaches show certain limitations and are not completely successful in limiting the insect pests. However, the sequence-specific gene silencing via RNA interference (RNAi) holds a great promise for effective management of agricultural pests. RNAi is naturally occurring conserved process responsible for gene regulation and defense against pathogens. The efficacy of RNAi varies among different insect orders and also depends upon various factors, including the target gene selection, method of dsRNAs delivery, expression of dsRNAs and presence of off-target effects. RNAi-mediated silencing of different insect genes involved in various physiological processes was found to be detrimental to insects growth, development and survival. In this article, we have reviewed the potential of RNAi-based strategies for effective management of insect pests. We have also discussed the various parameters, which are to be considered for host-induced RNAi-mediated control of insect pests without producing any effect on non-target organisms and environment.     

Oxygen-limited fed-batch process: an alternative control for Pichia pastoris recombinant protein processes

An oxygen-limited fed-batch technique (OLFB) was compared to traditional methanol-limited fed-batch technique (MLFB) for the production of recombinant Thai Rosewood β-glucosidase with Pichia pastoris. The degree of energy limitation, expressed as the relative rate of respiration (q _O/q _O,max), was kept similar in both the types of processes. Due to the higher driving force for oxygen transfer in the OLFB, the oxygen and methanol consumption rates were about 40% higher in the OLFB. The obligate aerobe P. pastoris responded to the severe oxygen limitation mainly by increased maintenance demand, measured as increased carbon dioxide production per methanol, but still somewhat higher cell density (5%) and higher product concentrations (16%) were obtained. The viability was similar, about 90–95%, in both process types, but the amount of total proteins released in the medium was much less in the OLFB processes resulting in substantially higher (64%) specific enzyme purity for input to the downstream processing.     

Pheromone trapping models for insect pest control

Pheromones have recently been suggested for use in insect pest control. We formulate a discrete version of a model with virgin females (or female equivalent of pheromone) in traps, and explore conditions under which this mechanism can eradicate the pest. Our model is density independent, thus when eradication is not possible, the pest increases without bound, in reality density dependent effects limit population growth. Successive refinements incorporating various features, show that delayed mating together with monogamy has a strong influence on the outcome, whereas other aspects of mating behaviour are relatively unimportant. All our models show that when males are in excess control is impossible but when some virgins are left unmated each day the outcome depends on the parameters. As the birth rate or survivorship increase, control by this method becomes more difficult.