ABSTRACT
Field evaluation of six grain storage technologies under hot and arid conditions (32-42 °C; rainfall < 450 mm/year) in two locations in Zimbabwe were conducted over two storage seasons. The treatments included three hermetic technologies (Purdue Improved Crop Storage bags, GrainPro Super Grainbags, metal silos); three synthetic pesticide-based treatments; and an untreated control, all using threshed sorghum grain. Sampling was at eight-week intervals for 32 weeks. Highly significant differences (p < 0.01) occurred between hermetic and non-hermetic treatments regarding grain damage, weight loss, insect pest populations, and grain moisture content; with the hermetic containers exhibiting superior grain protection. Weight losses were low (< 3%) in hermetic treatments compared to pesticide-based treatments (3.7 to 14.2%). Tribolium castaneum developed in metal silos, deltamethrin-incorporated polypropylene bags and a pesticide treatment containing deltamethrin 0.13% and fenitrothion 1% while Sitotroga cerealella developed in a pesticide treatment containing pirimiphos-methyl 0.16% + thiamethoxam 0.036%. Mechanisms of survival and development of these pests in the tested treatments and under similar climatic conditions need further elucidation. These hermetic technologies can be successfully used by smallholder farmers in developing countries as alternatives to synthetic pesticides for protecting stored-sorghum grain under hot and arid climatic conditions to attain household food security. To our knowledge, this is the first published study on modern hermetic storage of sorghum grain under typical smallholder storage conditions and involving stakeholders.
ABSTRACT
Climate change and variability are a threat to sustainable agricultural production in semi-arid areas of Malawi. Overdependence on subsistence rain-fed agriculture in these areas calls for the identification of sustainable adaptation strategies. A study was therefore conducted in Chikwawa, a semi-arid district in southern Malawi, to: (1) assess community's perception of a changing climate against empirical evidence, (2) determine their local adaptive measures, (3) evaluate the potential of irrigated agriculture as an adaptive measure in household food security and (4) challenges over access to available water resources. The study employed focus group discussions and key informant interviews to assess people's perceptions of climate change and variability and their desired interventions. To validate the people's perceptions, rainfall and temperature data for the period 1960-2010 were analysed. A participatory complete randomised experimental design in both rain-fed and dry season-irrigated conditions was conducted to assess a maize cropping system that would improve adaptation. The study established persistent declining yields from rain-fed production in part because of perennial rainfall failure. In response, the community has shifted its focus to irrigation as an adaptation strategy, which has in turn triggered water conflicts in the community over the control of the resource. Water legislation however fails to adequately provide for rules governing sharing of water resources between various stakeholders. This article therefore recommends development of an appropriate institutional framework that forms a strong basis for equitable distribution of water for irrigation in areas most vulnerable to extreme climate events - including droughts and floods.
ABSTRACT
Laboratory and field investigations were carried out to investigate the nature and role of the male pheromone emitted by the Dynast beetle Scapanes australis and to develop a mass trapping technique against this major coconut pest in Papua New Guinea. We report the biological data obtained from natural and synthetic pheromone, previously described as an 84:12:4 (w/w) mixture of 2-butanol (1), 3-hydoxy-2-butanone (2), and 2,3-butanediol (3). EAG recordings from natural and synthetic pheromone and a pitfall olfactometer were poorly informative. In contrast, extensive field trapping trials with various synthetic pheromone mixtures and doses showed that 1 and 2 (formulated in polyethylene sachets in 90:5 v/v ratio) were necessary and sufficient for optimum long-range attraction. Beetles were captured in traps baited with racemic 1 plus 2, with or without a stereoisomer mixture of 3 (2.5- to 2500-mg/day doses). Plant pieces, either sugarcane or coconut, enhanced captures by the synthetic pheromone, which was active alone. Traps with the pheromone caught both sexes in a 3:2 female-male ratio. A pheromone-based mass trapping led to the capture of 2173 beetles in 14 traps surrounding 40 ha of a cocoa-coconut plantation. The captures followed a log-linear decrease during the 125-week trapping program. The role of the male pheromone and its potential for crop protection are discussed.
