Biological control of pest Bruchidae may provide an important management strategy against infestation of stored grain legumes, a key source of dietary protein in developing countries. Previous related research has focused on the potential of parasitoids to control bruchids; the role of generalist predators in this application has not yet been extensively explored. / The anthocorid true bug Xylocoris flavipes (Reuter) exhibited a Type II density dependent functional response to five species of adult bruchids. The rate of kill of these large prey was quite low but fairly consistent and female predators were generally more effective. Of the species examined, only the eggs and neonate larvae of A. obtectus were accessible and predation on these stages was high. / Population interaction studies evaluating the effects of predator density and of time elapsed between infestation of commodity and predator addition indicated that adding the predator simultaneously with the pests significantly reduced the number of F$ sb1$, bruchid progeny for all species. Predator density contributed less to bruchid suppression than time of predator addition and bruchid progeny suppression was much greater than anticipated given the rate of kill observed in the functional response experiments. Reproduction by A. obtectus was almost entirely inhibited by the predator. / The high levels of suppression achieved with the predator indicated a significant biological control potential; however, the more fecund bruchid species with inaccessible immature stages continued to produce a large number of progeny. The predator was then combined with larval parasitoids capable of utilizing the internally-developing stages of the bruchids; bruchid suppression was considerably enhanced over the predator alone, and for the most fecund pests, suppression was greater than for the parasitoids alone.

[Truncated abstract] Faba bean (Vicia Faba L.) ranks third worldwide in overall production among coolseason legume crops and is used as a main source of protein both for food and feed purposes in many parts of the world. Australia is a major exporter of faba beans and the price received depends on the quality of the seed especially colour of the seed coat. Consumers don?t like faba beans that are dark coloured or that have blemishes on the seed coat. Environmental staining and storage discolouration deteriorate seed colour causing substantial economic losses to growers and grain handlers. To investigate the influence of environmental conditions, especially during pod/seed development and maturity, on the degree of environmental staining, field trials were conducted using four faba bean varieties (Fiord, Fiesta, Ascot and Cairo) in a range of environmental conditions under the Mediterranean-type climate of south western Australian grain belt. Although a majority of seeds had good colour but 3-25% were stained up to an unacceptable level across the trials and this varied with location and variety. Seeds formed later in plant development (located on the upper nodes of the plant) were more stained than seeds formed earlier (located on the lower nodes). This may be due to end of season environmental factors, such as high temperature and light intensity, and water and nutrient stress. Similarly seeds formed on small and weak plants, which may have developed under stressful conditions, had more staining than seeds formed on normal sized and healthy plants. Genotypic variation was also evident with Fiord showing greater staining than Ascot, Fiesta and Cairo. The cause of environmental staining appears to be complex but was associated with phenolic contents. Storage discolouration was influenced by a number of factors including temperature, seed moisture content, light and storage period and these were critical in determining storage life. ... Faba bean hardness, examined by the hard-to-cook test, also increased with increased storage temperature. There was a high negative correlation (r2 = 0.98) between storage temperature and cooking ability of faba bean. There was a three-fold increase in lignin content of faba bean stored at 50°C compared to those stored at 5°C and it was correlated with bean hardness (r2 = 0.98). Reduction in free phenolics was negatively correlated (r2 = 0.75) with bean hardness. The environmental staining in faba bean can be minimized with correct choice of varieties, robust agronomic practices to establish and maintain healthy plants and the use of mechanical graders and colour sorters. For minimizing storage discolouration faba beans must be dehydrated to ≤12% seed moisture content and stored in insulated bins (silos) or at least bins painted white and constructed under trees shades. In addition occasional flushing with N2 will further help reduce the colour darkening. The above approaches will improve quality, market opportunities, price and hence profitability of faba bean in the farming systems.

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