储粮害虫检测方法研究进展

科学、快速、准确进行储粮害虫检测是高效开展害虫综合防治的前提,也是保障粮食安全储藏的重要措施。本文根据国内外储粮害虫检测方法研究与应用进展情况,介绍了直观检查法、取样检查法、诱集检查法、电子检查法等储粮害虫检测方法及其优缺点,展望了储粮害虫检测技术发展方向,以期对我国储粮害虫发生的预测预报研究与应用有所裨益。     

RNAi在储粮害虫防治应用中的研究现状及展望

RNAi具有防治效果好、靶向性强等优点,因此被认为是下一代的害虫防控技术。近年,美国环境署(EPA)和食药局(FDA)先后批准了两款基于该技术的害虫防治及作物改良产品上市,标志着该技术在粮食领域的商品化开端。目前RNAi在多种储粮害虫中的可行性已经得到证实,但是该技术还存在一些问题,例如不同的害虫种类、dsRNA递送方式和分子设计差异都会影响RNAi防治效果。因此,本文系统性概述了RNAi技术在储粮害虫防治领域的研究及应用现状,并首次对RNAi技术在储粮害虫防控中的可行性、效率影响因素和增效方法进行了较为详细的总结。最后,还对RNAi技术在储粮害虫中的应用实践进行了展望,以期为该技术广泛应用于储粮害虫绿色防控提供理论基础。     

Factors influencing economic profitability of sampling-based integrated pest management of wheat in country elevators

Integrated pest management (IPM) in stored wheat could increase worker safety, reduce environmental concerns, and may reduce the chances of loss in grain quality. Managers of many country elevators, however, continue to use chemical-based approaches. To determine if this choice is economically justified, total costs (including both costs of implementation and costs of failing to control insects) for sampling-based IPM and calendar-based chemical approaches were simulated and compared for country elevators operating under typical conditions in the Central and Southern Plains of the United States.When we simulated a constant insect immigration rate into all bins at an elevator, results suggested that managers of country elevators storing hard red winter wheat under standardized assumptions and typical conditions have little economic incentive to switch from conventional calendar-based fumigation to sampling-based fumigation when both cost of treatment and cost of failing to control insects are considered. Under these assumptions, the reason sampling was not profitable was that fumigation eventually became necessary in all the bins, so sampling was just an extra cost. However, changing some of the standardized assumptions can make sampling-based fumigation profitable. In particular, the simulation suggests that if an elevator has some bins with a low rate of immigration and others with a medium rate of immigration, sampling-based fumigation becomes an economically attractive alternative. Other factors such as increased sanitation, reducing the cost of sampling, and storing the grain for shorter periods may also make a sampling-based approach more economical.     

Strawberries from integrated pest management and organic farming: Phenolic composition and antioxidant properties

Consumer awareness, pesticide and fertilizer contaminations and environmental concerns have resulted in significant demand for organically grown farm produce. Consumption of berries has become popular among health-conscious consumers due to the high levels of valuable antioxidants, such as anthocyanins and other phenolic compounds. The present study evaluated the influence that organic farming (OF) and integrated pest management (IPM) practise exert on the total phenolic content in 22 strawberry samples from four varieties. Postharvest performance of OF and IPM strawberries grown in the same area in the centre of Portugal and harvested at the same maturity stage were compared. Chemical profiles (phenolic compounds) were determined with the aid of HPLC-DAD/MS. Total phenolic content was higher for OF strawberry extracts. This study showed that the main differences in bioactive phytochemicals between organically and IPM grown strawberries concerned their anthocyanin levels. Organically grown strawberries were significantly higher in antioxidant activity than were the IPM strawberries, as measured by DPPH and FRAP assays.     

Qualitative reasoning and integrated management of the quality of stored grain: a promising new approach

Grain quality maintenance has traditionally been the responsibility of grain storekeepers who rely on measurements of grain or its milled products and on implicit knowledge gained through scientific results, common sense and job experience. Thus, managers of grain stores must comprehend the ecological, economic and technical consequences of their actions. Practical application of available knowledge by a grain-store manager may be greatly enhanced by the combination of fundamental concepts from stored-grain ecosystems with principles of expert systems (ES). The ES are computer programs with the capacity to mimic the reasoning logic of human experts when solving complex problems. They have been available as aids for stored-grain management for about a decade. The existing systems that focus mainly on pest management issues are briefly reviewed in the introductory part.Today, there is increasing pressure on the grain-handling industry to manage not only pests but also a broader range of parameters involved in grain quality maintenance. The implementation of a new type of ES to manage grain quality parameters during storage through an integrated qualitative approach is presented. In practice, most of the existing basic knowledge on progressive changes in grain quality attributes can be approximated by the statement of an initial state of quality and predictive models using only three variables: storage duration, grain temperature and water activity (or related moisture content). Combinations of qualitative variables through a logical decision network, predicting changes in different aspects of quality, may enable the prediction of quality from the initial diagnosis. Such a rule-based reasoning approach called “qualitative reasoning” has recently been developed as a decision support tool, starting from the diagnosis of quality attributes of a grain batch upon delivery at a grain store and anticipating the changes that will occur during the storage period. The new approach, based on high level reasoning methods and using a knowledge base (KB) of interactive rules about grain quality changes, is briefly presented. The implementation of this KB has focused on attributes that change very early in unsafe storage conditions such as germination capacity, micro-organism respiration, dry matter loss, visible moulding appearance, pest dynamics, cooling aeration effects and efficacy of residual protectants. Available models that may be introduced into the KB of the system have been reviewed. Most of the parameters of predictive models can be obtained by computation of existing experimental data. The prototype testing indicates that the system may give reliable quality diagnosis and prediction of optimal storage with a level of expertise and advice comparable to human experts. The additional work needed to extend the scope and domain of applicability of this new generation of ES is discussed. The procedure of qualitative reasoning applied to the whole grain ecosystem is shown to be a promising tool for detecting the weaknesses of basic knowledge about changes in cereal quality during storage.     

Stored Grain Advisor Pro: Decision support system for insect management in commercial grain elevators

A decision support system, Stored Grain Advisor Pro (SGA Pro) was developed to provide insect pest management information for wheat stored at commercial elevators. The program uses a model to predict future risk based on current insect density, grain temperature and moisture. A rule-based system was used to provide advice and recommendations to grain managers. The software was tested in a research program conducted at commercial grain elevators in Kansas and Oklahoma, USA. A vacuum-probe sampler was used to take ten 3-kg grain samples in the top 12 m of each bin that contained wheat. After the insect species and numbers were determined for each sample, the data were entered into SGA Pro. A risk analysis and treatment recommendation report for all bins was presented to the grain managers every 6 weeks. SGA Pro correctly predicted for 71–80% of bins whether the grain was safe or at high risk of dense infestation and grain damage. SGA Pro failed to predict “unsafe” insect densities in only 2 out of 399 Kansas bins (0.5%) and in none of 114 bins in Oklahoma. Grain managers who followed SGA Pro's recommendations tended to fumigate only the bins with high insect densities instead of fumigating all bins at their facility. This resulted in more efficient insect pest management because fumigating bins only when insect densities exceeded economic thresholds and treating only the bins that required fumigation minimized the risk of economic losses from insects, reduced the cost of pest management, and reduced the use of grain fumigant.     

Olfactory host location in the rusty grain beetle parasitoid Cephalonomia waterstoni (Gahan) (Hymenoptera: Bethylidae)

Parasitoids can suppress populations of their host and thus play a primary role in Integrated Pest Management. The parasitic wasp Cephalonomia waterstoni Gahan (Hymenoptera: Bethylidae) is a natural enemy of the rusty grain beetle Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae). In the stored product environment, stimuli deriving from plant products, damaged plant products and hosts might be important for host location by the parasitoids. We tested the response of female parasitoids to odours deriving from infested and uninfested plant products, the grain dust produced by feeding primary pests, and various life stages of the rusty grain beetle. The olfactory response of C. waterstoni was found to be strongly elicited both by chemicals emitted by the dust, adult C. waterstoni and C. waterstoni third and fourth instar larvae. Our findings may contribute towards biological control of C. ferrugineus and the chemical ecology of olfactory host location by C. waterstoni.     

The biology,ecology and management of the larger grain borer,Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae)

The invasive larger grain borer, Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), originating from Meso-America, is a devastating stored product pest of maize (Zea mays L.) and cassava (Manihot esculenta). This species can destroy up to 40% of stored maize within four months. Despite four decades of research, P. truncatus has spread throughout Africa, while decimating maize and cassava production. Given the continuing problems with P. truncatus, the likelihood for its continued range expansion under climate change, and its status as a species of concern in many countries, the objective of this review was to provide an updated and comprehensive freely accessible record of the distribution and spread, biology, development, and ecology, host preferences, chemical ecology, detection, and monitoring, and management of P. truncatus. We conducted a search of the literature from 1911 to 2021 using Google Scholar and Web of Science to find all papers related to key search terms. We found that P. truncatus has been recorded in 36 countries across the globe, including 21 now in Africa. A recent predictive model found that the insect has been limited to tropical and subtropical regions but could likely spread to temperate regions as temperatures rise with climate change. Conspecifics respond to their two component, male-produced aggregation pheromone early after eclosion, but quickly switch to other cues as older adults. At close-range, P. truncatus may use food cues, but host volatiles are not involved in long-range host finding of commodities. Research on managing P. truncatus has mostly focused on chemical control to the detriment of other tactics, with the most promising tactic likely to be the different hermetic storage technologies. Many outstanding areas of basic behavior and ecology remain to be assessed for P. truncatus. We highlight specific areas that should be prioritized for further work in order to better manage and reduce the impact of this invasive insect pest.     

Deep-bed simulation of the cooling of stored grain with ambient air: a test bed for ventilation control strategies

A simulation model for grain cooling is presented and verified against experimental data. The model is applied to grain cooling during a typical season at a location in the southeast of the U.K. Fan control strategies are investigated, and the use of differential control based on the grain to air temperature difference is found to be effective. In the simulation, barley placed in store at 16% w.b. moisture content (0.191 d.b.) and 30 °C in late July was cooled to 15 °C in 1 month using a 2 °C differential, whereas for malting barley it was necessary to use a 6 °C differential to reduce rewetting. Rewetting of the bed at the air entry region was significant in all situations simulated and, for malting barley, the heat of absorption significantly affected cooling. The simulations for wheat and barley were very similar. The results indicate that cooling, even during this warm period, can achieve temperatures which will greatly decelerate insect development.     

Low-temperature aeration to control Indianmeal moth, Plodia interpunctella (Hübner), in stored grain in twelve locations in the United States: a simulation study

Aeration management strategies were developed to control cold-acclimated and diapausing Indianmeal moth, Plodia interpunctella (Hübner), larvae in grain bins during winter in north- and east-central regions of the US. The application in this study focuses on corn because it is the dominant crop in these regions, but we believe that the analyses can be applied to other grains as well. Contour maps for hours below −10 °C for the months of December, January, and February were developed to help effective planning and management of aeration to control overwintering stored-grain insects. Two cumulative lethality index (CLI) models were developed to estimate mortality of laboratory-reared (diapausing without cold-acclimation) and field-collected (cold-acclimated, and diapausing with cold-acclimation) P. interpunctella larvae under changing temperature conditions. The CLI models were used for evaluating aeration management strategies. Simulation studies were conducted using 30 years of weather data for 12 locations in north- and east-central regions of the US to evaluate different aeration management strategies for controlling P. interpunctella larvae. For each strategy, temperatures of headspace air and grain in the top meter of the grain mass were simulated using an existing model for the period of December-February. The tested management strategies included no aeration, continuous aeration, and intermittent aeration by controlling fan operation. During aeration, air was pulled from the headspace downward through the grain with an airflow rate of 0.11 m³/min-t (0.1 cfm/bu). Simulation results indicated that a fan control strategy that turned the aeration fan on when the grain temperature at 0.4-m depth was greater than the headspace-air temperature was the best strategy for managing P. interpunctella larvae in all tested locations. For this strategy, the CLI model indicated that 100% mortality of P. interpunctella larvae could be achieved at a grain depth of 0.4 m from the top grain surface in all locations. For this strategy, the aeration fan operated about 10% of the time from December to February. The average cost of electrical energy required for aeration fan operation with this strategy for all locations was 1.3 ¢/t (0.033 ¢/bu) based on an electrical energy cost of 7 ¢/kWh.