Occurrence of aflatoxins and its management in diverse cropping systems of central Tanzania

The staple crops, maize, sorghum, bambara nut, groundnut, and sunflower common in semi-arid agro-pastoral farming systems of central Tanzania are prone to aflatoxin contamination. Consumption of such crop produce, contaminated with high levels of aflatoxin B₁ (AFB₁), affects growth and health. In this paper, aflatoxin contamination in freshly harvested and stored crop produce from central Tanzania was examined, including the efficacy of aflatoxin mitigation technologies on grain/kernal quality. A total of 312 farmers were recruited, trained on aflatoxin mitigation technologies, and allowed to deploy the technologies for 2 years. After 2 years, 188 of the 312 farmers were tracked to determine whether they had adopted and complied with the mitigation practices. Aflatoxigenic Aspergillus flavus and aflatoxin B1 contamination in freshly harvested and stored grains/kernels were assessed. A. flavus frequency and aflatoxin production by fungi were assayed by examining culture characteristics and thin-layer chromatography respectively. AFB₁ was assayed by enzyme-linked immunosorbent assay. The average aflatoxin contamination in freshly harvested samples was 18.8 μg/kg, which is above the acceptable standard of 10 μg/kg. Contamination increased during storage to an average of 57.2 μg/kg, indicating a high exposure risk. Grains and oilseeds from maize, sorghum, and sunflower produced in aboveground reproductive structures had relatively low aflatoxin contamination compared to those produced in geocarpic structures of groundnut and bambara nut. Farmers who adopted recommended post-harvest management practices had considerably lower aflatoxin contamination in their stored kernels/grains. Furthermore, the effects of these factors were quantified by multivariate statistical analyses. Training and behavioral changes by farmers in their post-harvest practice minimize aflatoxin contamination and improve food safety. Moreover, if non-trained farmers receive mitigation training, aflatoxin concentration is predicted to decrease by 28.9 μg/kg on average.     

Grain injury models for Prostephanus truncatus (Coleoptera: Bostrichidae) and Sitophilus zeamais (Coleoptera: Curculionidae) in rural maize stores in West Africa

Prostephanus truncatus (Horn) and Sitophilus zeamais Motschulsky have been reported as the two most serious pests of stored maize in sub-Saharan Africa and smallholder farmers are in urgent need of guidelines for their proper management. In this article we investigate the injury rates attributable to these two species in terms of percentage weight loss and percentage grain damage, and we derive functional response models for the two species on maize. The models successfully described the progression of grain injury in an extensive data set compiled from previously published studies, comprising 46 time series of data relating maize injury and insect pest density. The grain injury models can be used in conjunction with predictive models of pest population dynamics to guide the development of integrated management strategies for postharvest maize pests in West Africa and comparable regions elsewhere.     

Development of combined use of neem (Azadirachta indica) and water management for the control of culicine mosquitoes in rice fields

Abstract. Crude neem products have earlier shown considerable promise for control of culicine mosquito vectors in rice fields as a by-product of their agricultural use as fertilizers, but suffer from disadvantages of bulkiness and lack of stability in storage. Relatively stable lipid-rich fractions of neem were shown to be as effective as good-quality crude neem products in control of breeding of culicine vectors of Japanese encephalitis, and also produced a slight but significant reduction in populations of anopheline pupae. Neem-based formulations coated over urea significantly increased grain yield, but used alone did not, whereas combining the use of neem-coated urea and water management by intermittent irrigation had a greater effect on grain yield than that of water management alone. The neem fractions were relatively cost-effective, and the combined water management and neem-coated urea strategy is acceptable to farmers, who are already aware of the benefits of the use of neem-coated urea, and of water management. This technology therefore has considerable promise as an environmentally benign method of rice-field mosquito control that could be sustainably implemented by farmers.     

Traditional Maize Storage Methods of Mayan Farmers in Yucatan, Mexico: Implications for Seed Selection and Crop Diversity

For small-scale farmers who maintain genetically diverse crop populations, aspects of the storage of their seeds and harvest may be just as important for successful farming as those related to productivity. The community of Yaxcaba, Yucatan, Mexico was studied to understand how the conditions under which Maya farmers store their maize harvests influence their seed selection practices and the diversity of maize varieties grown. Most farmers select their maize seed based primarily on ear characteristics and secondarily on grain characters. Farmers incorporate storability concerns by selecting for an archetypal healthy ear and by conducting selection in several steps between harvest and planting of the subsequent crop generation. Most farmers store their maize harvest in the husk, initially in the field and then in rustic granaries constructed of logs and palm thatch, in which farmers conserve separately their different seed lots. All local landrace populations show morphological adaptation (principally husk characteristics) for local storage conditions, indicating that storability has been an important selection pressure on traditional maize. Storability also appears to be a key factor working against the straightforward adoption of improved maize seed in Yaxcaba. Local farmers value many qualities of improved maize varieties, but their principal complaint is that improved maize cannot be conserved reliably under local storage conditions. Nearly all farmers who utilize improved seed stock in Yaxcaba grow locally adapted or ‘creolized’ versions of improved varieties, displaying characteristics of local maize landraces that facilitate their storage.     

Pest management in traditional maize stores in West Africa: a farmer's perspective

Farmers in the Republic of Benin have few resources to invest in protection of stored maize, and prophylactic pesticide application is often recommended by extension and development agencies. Neither the efficacy nor profitability of such an application in traditional maize storage facilities has been addressed quantitatively. In this study, existing management options for stored maize were evaluated monthly over 6 mo in central and southern Benin with respect to their effects on grain injury and on densities of Prostephanus truncatus (Horn) and Sitophilus zeamais Motschulsky. P. truncatus infested 54% of the experimental stores in the study even though Teretrius nigrescens (Lewis), a natural enemy introduced against P. truncatus, was well established in the region. S. zeamais was the most common pest, found in 85% of the experimental storage facilities. Prophylactically treated maize was, on average, worth more than untreated maize for month 1 through 5 in southern Benin, after taking into account market price, pesticide costs, percentage grain damage and weight loss, but maize storage was not profitable overall. No difference was observed between treatments in central Benin. After 6 mo treated storage facilities were not significantly different from untreated storage facilities in terms of either percentage damage or profit in either region. A rapid scouting plan intended to provide farmers with a means for identifying storage facilities at greatest risk of severe P. truncatus infestation was field validated. Given that unsafe pesticide use is prevalent in Benin, research and extension services should clearly state the limitations to prophylactic treatment and increase the effort to educate farmers on appropriate pesticide use, store monitoring and marketing.     

Biological nitrogen fixation in resource-poor agriculture in South Africa

Farm lands of resource-poor communities in South Africa are depleted of nutrients due to continuous mono-cropping, limited use of fertilisers, and sometimes leaching caused by high rainfall. Despite the well-known advantages of biological nitrogen fixation (BNF) in cropping systems, less than 10% of the grain crops planted annually in these areas are legumes. Using a participatory research and development approach, resource-poor farmers were introduced to conservation agriculture (CA) practices, including BNF, that promoted zero (or reduced) tillage, increased retention of soil cover, as well as crop diversification. Because crop rotation and intercropping of legumes with cereals are known to contribute to soil fertility while enhancing food security, resource-poor farmers from various Provinces in South Africa were trained on the benefits of legume culture for eight years. As a result, these resource-poor farmers did not only get training in inoculation techniques, but were also supplied with inoculants for use on their farms. Data collected from Farmers Demonstration Trials at Belvedere, Dumbarton and Lusikisiki, showed that the grain and fodder yield of maize planted after legumes, and maize intercropped with legumes, were comparable to those of maize receiving high N fertilizer dose (i.e. 54 kg N at planting and 54 kg N as top-dressing). The same data further showed thatRhizobium inoculation, when combined with application of low levels of P and K, significantly increased crop yields within farmers’ trial plots. BNF therefore offers a great opportunity for resource-poor farmers in South Africa to increase their crop yields and thus improve the quality of their livelihoods through the adoption of affordable and sustainable biological technologies that enhance soil fertility.     

Ethnobotany of the Monpa ethnic group at Arunachal Pradesh, India

Background

Barley is the number one food crop in the highland parts of North Eastern Ethiopia produced by subsistence farmers grown as landraces. Information on the ethnobotany, food utilization and maintenance of barley landraces is valuable to design and plan germplasm conservation strategies as well as to improve food utilization of barley.

Methods

A study, involving field visits and household interviews, was conducted in three administrative zones. Eleven districts from the three zones, five kebeles in each district and five households from each kebele were visited to gather information on the ethnobotany, the utilization of barley and how barley end-uses influence the maintenance of landrace diversity.

Results

According to farmers, barley is the "king of crops" and it is put for diverse uses with more than 20 types of barley dishes and beverages reportedly prepared in the study area. The products are prepared from either boiled/roasted whole grain, raw- and roasted-milled grain, or cracked grain as main, side, ceremonial, and recuperating dishes. The various barley traditional foods have perceived qualities and health benefits by the farmers. Fifteen diverse barley landraces were reported by farmers, and the ethnobotany of the landraces reflects key quantitative and qualitative traits. Some landraces that are preferred for their culinary qualities are being marginalized due to moisture shortage and soil degradation.

Conclusions

Farmers' preference of different landraces for various end-use qualities is one of the important factors that affect the decision process of landraces maintenance, which in turn affect genetic diversity. Further studies on improving maintenance of landraces, developing suitable varieties and improving the food utilization of barley including processing techniques could contribute to food security of the area.     

Complex agro-ecosystems for food security in a changing climate

Attempts to increase food crop yields by intensifying agricultural systems using high inputs of nonrenewable resources and chemicals frequently lead to de-gradation of natural resources, whereas most technological innovations are not accessible for smallholders that represent the majority of farmers world wide. Alternatively, cocultures consisting of assemblages of plant and animal species can support ecological processes of nutrient cycling and pest control, which may lead to increasing yields and declining susceptibility to extreme weather conditions with increasing complexity of the systems. Here we show that enhancing the complexity of a rice production system by adding combinations of compost, azolla, ducks, and fish resulted in strongly increased grain yields and revenues in a season with extremely adverse weather conditions on East Java, Indonesia. We found that azolla, duck, and fish increased plant nutrient content, tillering and leaf area expansion, and strongly reduced the density of six different pests. In the most complex system comprising all components the highest grain yield was obtained. The net revenues of this system from sales of rice grain, fish, and ducks, after correction for extra costs, were 114% higher than rice cultivation with only compost as fertilizer. These results provide more insight in the agro-ecological processes and demonstrate how complex agricultural systems can contribute to food security in a changing climate. If smallholders can be trained to manage these systems and are supported for initial investments by credits, their livelihoods can be improved while producing in an ecologically benign way.     

土壤水分亏缺对水稻茎秆贮藏碳水化合物向籽粒运转的调节

以两个茎秆贮藏物质利用效率不同的水稻(Oryza sativa)杂交组合(‘汕优63’和‘Pc311/早献党’)为材料,进行土壤水分亏缺处理(Water-deficit),以水层灌溉为对照(Well-watered),研究水分亏缺对水稻茎贮藏性碳水化合物运转及其关键酶活性的调节作用。结果表明,水分亏缺促进了水稻茎秆贮藏物质的运转和对籽粒产量的贡献,开花前茎秆贮藏的碳水化合物对产量贡献率分别提高了1.9~3.0倍(与水层灌溉相比)。土壤水分亏缺诱导了水稻茎节间α-淀粉酶、β-淀粉酶、α-葡萄糖苷酶、D-酶活性上升,但淀粉磷酸化酶受到了抑制,说明土壤水分亏缺加强水稻茎秆贮藏淀粉水解途径,而不是磷酸解途径。就蔗糖代谢而言,土壤水分亏缺提高了蔗糖磷酸合成酶的活性和活化状态,抑制蔗糖转化酶活性,促进蔗糖合成,加速贮藏物质快速降解和转移,从而调节稻株贮藏碳水化合物向籽粒的分配。     

北方农牧交错带农村居民食物消费特征

北方农牧交错带是我国典型生态脆弱区之一,恶劣的自然环境和落后的基础条件制约着生产和消费的发展。自2000年起,当地实施了一系列生态工程措施,引导农牧民由粗放型生产经营方式向集约型转变,改善区域生态环境的同时也优化了农牧业生产格局,居民食物消费结构随之改变。由于入户跟踪调查数据较难获取,现有食物消费研究缺少长时间尺度的消费特征变化研究,且农区和牧区的对比研究较少。以赤峰和鄂尔多斯为例,采用基于随机抽样调查方法收集的食物消费面板数据,对比研究2000—2020年典型农牧交错区的食物消费类型、结构及其数量变化。结果表明：生态工程实施以来,农牧居民食物消费种类趋于多样化,但消费结构不尽合理。赤峰趋于传统农区以谷类为主的消费结构,其谷类消费正在稳步减少,其他食物类型的消费增加;鄂尔多斯表现为多粮肉、少果蔬的消费结构,兼具农牧区的消费特点,其谷类和畜肉消费的年际波动较大,体现出传统牧区粗放式经营下产出不稳定的特点。食物消费总量持续增长,截至2020年,农牧居民谷类消费偏多,肉蛋类、豆类和食用油消费较为适度,薯类和果蔬类消费不足,奶类消费涨幅虽十分突出,但仍比我国膳食标准低20倍以上,因此减少谷类消...     

Using Realistic Evaluation to understand how interventions work on dairy farms

Interventions that aim to help farmers change on-farm practices recommend that advisors communicate effectively with farmers, work collaboratively to set goals and provide farmers with resources that are applicable to the farm context. We developed an intervention that aimed to help farmers modify and use a standard operating procedure (SOP) for colostrum management; failure of passive transfer of immunoglobulins is common on dairy farms and SOPs for colostrum management are increasingly required by farm animal welfare assurance programs. We used Realistic Evaluation to evaluate whether, how and why our intervention to help farmers modify and use SOPs for colostrum management facilitated change and provide recommendations based on our approach that can improve the design and implementation of future interventions. We used a multiple case study on five farms over 8 months, collecting data through interviews, participant observation, document analysis and field notes. We identified three mechanisms that influenced whether participants modified and used their SOP. The purpose mechanism distinguished between participants who thought the aim of the SOP was for farm staff to learn and understand how to complete a task versus those who thought that the SOP was only useful for compliance with assurance programs. The utility mechanism distinguished between participants who thought that the SOP would be helpful for daily use on their farm, versus those who did not. The physical text mechanism distinguished between participants who used the templates we provided to modify and use their SOP, versus those who did not. A key contextual factor on all farms was participant belief of having capable and engaged staff on their farm; modification and use of the SOP did not occur unless this was the case. To facilitate change, intervention developers should actively participate in the intervention to develop an understanding of farmer needs, understand the purpose behind different goals set by farmers and integrate tools, advice and resource demonstrations when possible. We conclude that Realistic Evaluation is a useful framework for evaluating how contexts and mechanisms generate outcomes on farms, and to understand how, and in which contexts, complex interventions facilitate change. We suggest that this approach can improve the success of interventions and help direct the approaches used on different farms.     

An agent‐based modelling approach to evaluate factors influencing bioenergy crop adoption in north‐east Scotland

An agent‐based modelling (ABM) framework was adapted to assess bioenergy crop uptake and integrate social and economic processes with biophysical elements. Survey results indicated that economic rationalisation was intrinsic to farmers’ decision‐making, but was not the only consideration. This study presents an approach, set within an established resource management framework, to incorporate a number of key socio‐economic factors, which we call Mitigation Willingness Factors (MWFs), using survey data collected from farmers and land managers, into the ABM. The MWFs represent farmers’ willingness to compromise revenue in order to reduce GHG emissions, derived from their attitudes to climate change and the ability of different economic mechanisms to stimulate energy crop uptake. Adoption of bioenergy crops of different farmer types and farming enterprises was also assessed. Adoption rates and scenarios that take into account noneconomic factors are presented, and particular farming enterprises that may respond more positively to policy initiatives are identified.     

Analysis of the benefits to wheat yield from assimilates stored prior to grain filling in a range of environments*

Grain yields of rainfed agriculture in Australia are often low and vary substantially from season to season. Assimilates stored prior to grain filling have been identified as important contributors to grain yield in such environments, but quantifying their benefit has been hampered by inadequate methods and large seasonal variability. APSIM-Nwheat is a crop system simulation model, consisting of modules that incorporate aspects of soil water, nitrogen (N), crop residues, crop growth and development. Model outputs were compared with detailed measurements of N fertilizer experiments on loamy soils at three locations in southern New South Wales, Australia. The field measurements allowed the routine for remobilization of assimilates stored prior to grain filling in the model to be tested for the first time and simulations showed close agreement with observed data. Analysing system components indicated that with increasing yield, both the observed and simulated absolute amount of remobilization generally increased while the relative contribution to grain yield decreased. The simulated relative contribution of assimilates stored prior to grain filling to grain yield also decreased with increasing availability of water after anthesis. The model, linked to long-term historical weather records was used to analyse yield benefits from assimilates stored prior to grain filling under rainfed conditions at a range of locations in the main wheat growing areas of Australia. Simulation results highlighted that in each of these locations assimilates stored prior to grain filling often contributed a significant proportion to grain yield. The simulated contribution of assimilates stored prior to grain filling to grain yield can amount to several tonnes per hectare, however, it varied substantially from 5–90% of grain yield depending on seasonal rainfall amount and distribution, N supply, crop growth and seasonal water use. High N application often reduced the proportion of water available after anthesis and decreased the relative contribution of remobilization to grain yield as long as grain yields increased, particularly on soils with greater water-holding capacity. Increasing the capacity or potential to accumulate pre-grain filling assimilates for later remobilization by 20% increased yields by a maximum of 12% in moderate seasons with terminal droughts, but had little effect in poor or very good seasons in which factors that affect the amount of carbohydrates stored rather than the storage capacity itself appeared to limit grain yield. These factors were, little growth due to water or N deficit in the weeks prior to and shortly after anthesis (when most of the assimilates accumulate for later remobilization), poor sink demand of grains due to low grain number as a result of little pre-anthesis growth or high photosynthetic rate during grain filling. Increasing the potential storage capacity for remobilization is expected to increase grain yield especially under conditions of terminal drought.     

Combating food insecurity on sandy soils in Zimbabwe: The legume challenge

The continued rise in mineral fertilizer costs has demanded cheaper alternative N sources for resource-constrained smallholder farmers, with N₂-fixing legumes presenting a viable option to maintain crop productivity. A study was conducted over two years on a coarse sandy soil (Lixisol with <80 g clay kg^?1 soil) to determine the productivity of (i) five grain legumes, (ii) a green manure legume, and (iii) maize on smallholder farmers’ fields, identified as SOFECSA Leaming Centres, in Chinyika, north-east Zimbabwe. The objective of the study was to promote appropriate targeting of soil fertility technologies to different farmer resource groups. Emphasis was put on establishing the scope for improving nutrient resource allocation efficiency and crop yields in relation to different management practices as dictated by resource endowment. Both biomass and grain yield results indicated a general conformity to farmer resource group as follows: Resource-endowed farmers (RG1) > Intermediate farmers (RG2) > Resource-constrained farmers (RG3). Although overall biomass productivity for the grain legumes was generally low, <2.8 Mg ha^?1 across all Learning Centres, soyabean grain yields increased by between 30% (RG1) and >500% (RG3) over the two seasons. However, there was a general preference for bambara nut by RG3 farmers who cited low cash demands in terms of seed and external inputs, and pest-resistance compared with other grain legumes. Increased maize grain yields following legumes, and which exceeded 7 Mg ha^?1 for RG1 under green-manure, was apparently due to an increase in soil available N. The results showed scope for enhancing the contribution of legumes to both soil fertility and household nutrition within smallholder farming systems if targeted according to farmers’ resource endowment. The challenge is availing the minimum level of external inputs to RG3 farmers to achieve significant yield benefits on poor soils. The paper presents three main scenarios constituting major challenges for integrating legumes into the current farming systems.     

中国绿色食品产业化发展的理论与实践

对天津蓟县国家级绿色食品生产示范区和国家级龙头企业草原兴发集团进行案例研究,得出绿色食品产业化经营的基本框架结构及其理论依据。绿色食品产业化的基本框架是由农产品生产、加工企业、农户、市场销售部门等组成,各部分之间存在特定的、相互依存的经济技术关系,共同构成统一的产业结构体系。在农业产业化、农业可持续发展、绿色经济、绿色营销、市场经济、以及农业生态学等理论与原理的指导下,该体系以市场为导向,以提高经济效益为中心,按照“市场牵龙头,龙头带基地、基地联农户”的形式,优化组合各生产要素,实行区域化布局、专业化生产、一体化经营、社会化服务、企业化管理。实现了资源持续利用和生态环境优化,从而获得最佳的社会、经济、生态综合效益,有利于提高中国农业的综合生产能力和出口能力。     

达乌尔鼠兔扩散过程中的生境选择

通过调控牧压,研究了达乌尔鼠兔扩散过程中的生境选择。结果表明,放牧活动强了草原植被的斑块性,改变了植被为鼠兔提供的资源条件,导致鼠兔斑块间的扩散和扩散鼠兔对不同植被斑块的生境选择。     

Impact of food processing and detoxification treatments on mycotoxin contamination

Mycotoxins are fungal metabolites commonly occurring in food, which pose a health risk to the consumer. Maximum levels for major mycotoxins allowed in food have been established worldwide. Good agricultural practices, plant disease management, and adequate storage conditions limit mycotoxin levels in the food chain yet do not eliminate mycotoxins completely. Food processing can further reduce mycotoxin levels by physical removal and decontamination by chemical or enzymatic transformation of mycotoxins into less toxic products. Physical removal of mycotoxins is very efficient: manual sorting of grains, nuts, and fruits by farmers as well as automatic sorting by the industry significantly lowers the mean mycotoxin content. Further processing such as milling, steeping, and extrusion can also reduce mycotoxin content. Mycotoxins can be detoxified chemically by reacting with food components and technical aids; these reactions are facilitated by high temperature and alkaline or acidic conditions. Detoxification of mycotoxins can also be achieved enzymatically. Some enzymes able to transform mycotoxins naturally occur in food commodities or are produced during fermentation but more efficient detoxification can be achieved by deliberate introduction of purified enzymes. We recommend integrating evaluation of processing technologies for their impact on mycotoxins into risk management. Processing steps proven to mitigate mycotoxin contamination should be used whenever necessary. Development of detoxification technologies for high-risk commodities should be a priority for research. While physical techniques currently offer the most efficient post-harvest reduction of mycotoxin content in food, biotechnology possesses the largest potential for future developments.     

On farm plant reintroduction: A decision framework for plant conservation translocation in EU agro-ecosystems

The increased demand of food produced through sustainable agriculture has resulted in localised amelioration of intensive management imposed by agroecosystems. However, these newly available niches are often isolated and plant species may not be able to recolonise fragmented agroecosystems from where they have been extirpated. Plant reintroduction can overcome dispersal limitation in agroecosystems but may also generate conflicts that jeopardise conservation efforts. Conflicts arise when reintroductions are perceived to place constraints on the management and productivity of agroecosystems: the translocated plants may require space sharing with crops, may have negative effects on crop yields, and come with the expectation that farmers must modify their farming practices and accommodate legal obligations deriving from protected species status. Benefits include economic incentives that pay farmers through CAP, the conservation of nature, ecosystem services, an effective marketing strategy and increased aesthetic value that might generate ecotourism.We discuss the practical implications of the abovementioned issues by reference to two cases of European species in which different approaches to reintroduction resulted in opposite outcomes (i.e., consensus vs. opposition). Coexistence of threatened plants and crops is possible if farmers and local stakeholders are involved in a conservation project from an early stage and if farmers conservation efforts turn into benefits for their income. Based on these considerations, we propose a strategic framework to promote reintroduction of threatened plants in agroecosystems (land sharing) and policy advancement aimed at recognising the role of farmers in maintaining biodiversity on their lands.     

啮齿动物分散贮食的影响因素

分散贮藏食物是许多啮齿动物所采取的一种重要的觅食策略。分散贮藏方式对于植物的幼苗建成、更新、群落演替和生态系统功能的维持有着积极的意义。多种因素影响啮齿动物对食物分散贮藏。内部因素有性别、年龄、社群关系、饥饿状态等;外部因素包括食物特征、竞争与盗食环境条件等。这些因素并非独立地发挥作用,内部因素受外部刺激的综合影响,而且外部因素只能通过改变动物的内部状态才能发挥作用。特别是在一些室内的或围栏实验中,实验设计的差异不仅影响动物的食物贮藏及其管理,也会造成实验结果的不同。     

The effect of dominance on food hoarding: a game theoretical model

Many food hoarding animals live in small groups structured by rank. The presence of conspecifics in the hoarding area increases the risk of losing stored supplies. The possibility of stealing from others depends on a forager's rank in the group. Highly ranked individuals can steal from subordinates and also protect their own caches. Since storing incurs both costs and benefits, the optimal hoarding investment will differ between individuals of different rank. In a game theoretical model, we investigate how dominant and subordinate individuals should optimize their hoarding effort. Our model imagines animals that are large-scale hoarders in autumn and dependent on stored supplies for winter survival. Many examples can be found in the bird families Paridae and Corvidae, but the model can be used for any hoarding species that forage in groups. Predictions from the model are as follows: First, subordinates should store more than dominants, but in a predictable environment, this difference will decrease as the environment gets harsher. Under harsh conditions, dominants should store almost as much as subordinates and, later, spend almost as much time retrieving their own caches as subordinates. Second, if on the other hand, bad winter conditions were not expected when storing, dominants should spend more time pilfering caches from subordinates. Third, in populations that are highly dependent on stored supplies, dominants should store relatively more than in populations that are less dependent on stored supplies. Fourth, harsher environments will favor hoarding. And finally, if dominant individuals store, it implies that hoarders have a selfish recovery advantage over conspecific pilferers.