Farmers in sub-Saharan Africa have repeatedly prioritised the need for improved methods of storage pest control. Reduction of storage losses will help to reduce the vulnerability of small-scale producers by improving household food security and improving income-generating opportunities and livelihood outcomes. Field trials in Zimbabwe have demonstrated that diatomaceous earths (DE) are highly effective and persistent grain protectants against the major storage insect pests attacking maize, sorghum and cowpeas. However, high application rates of DEs were required to prevent bostrichid beetle damage. As the damage caused by the bostrichid, Prostephanus truncatus, at the farm level in affected areas of sub-Saharan Africa is often much more severe than that of other storage insect pests, it is critical that any protectants used on grain are effective against it. The studies reported here evaluated combinations of Protect-It (R) DE with low levels of pyrethroids, plant extracts or soil bacteria metabolites against P. truncatus. Deltamethrin and permethrin, which are synthetic pyrethroids, caused a high knockdown effect and prevented progeny emergence of P. truncatus at application rates of 0.025 mg/kg and 2 mg/kg, respectively, and no further effects from the addition of Protect-It (R) were observed. The combinations of DE and plant extracts or soil bacteria metabolites, formulated as "All Natural" and "Spindeba", also prevented progeny emergence of P. truncatus at application rates of 50-100 ppm. The results are discussed in the context of improving the efficacy of DE against P. truncatus for use by small-scale producers in developing countries.

The "StorMax Insector" is a new, electronic device for detecting insects in stored grain. Naturally occurring arthropods captured using Insector prototypes were compared with those captured using Guard (R) pitfall traps (GGPT) and Storgard (R) WB Probe II (TM) traps (WBII) in 5 small bins containing wheat. Trap location within the bin and the Presence or absence of sunlight were also examined for their effect on the number of arthropods collected in the 3 trap types. The arthropods captured during the study consisted of 5 species of beetles, 2 parasitic Hymenoptera, a member of the Psocidae family, and mites. As expected, all arthropods were not captured in every bin during the 2-day sampling period in November when grain temperatures averaged 22.4 degrees C. Total insects and mites captured were affected by trap type and trap location within the bins. Significantly more arthropods were captured in the Insector and WBII traps than in the GGPT traps. Traps located on the south sides of the bins captured more arthropods than traps located in the northern portions of the bins. Presence or absence of sunlight did not affect the total number of insects and mites collected in the traps. When comparing species, more R. dominica were captured in the WBII trap than in the other two trap types and more A. advena were captured in the Insector than in the GGPT trap. More R. dominica were captured in traps located in the southern part of the bin than in the northern portion. Traps in bins receiving sunlight had significantly more mites than bins with no sunlight. Just the opposite was true for A. advena. Knowing that trap type, trap location, and the presence or absence of sunlight can affect trap capture is important in interpreting species counts for developing a management strategy to control pests.

A decision-support system, Stored Grain Advisor Pro, was developed to conduct risk analysis of large concrete commercial elevator facilities. A vacuum-probe sampler was used to take ten 3-kg grain samples in the top 12 to of each bin at grain elevators. After the insect species and numbers are determined for each sample, the data are entered into the risk analysis software. The program uses a model to predict future risk based on current insect density, grain temperature and moisture. The information is presented as a bin board layout to the manager. Recommended treatment strategies and an economic analysis are presented to the manager. Stored Grain Advisor correctly predicted for 71-80% of bins whether they were either safe or at high risk. In only 2 of 399 bins in Kansas, and in zero bins in Oklahoma did it predict that bins were safe when in fact they became infested weeks later. Elevator operators using the program tended to fumigate only the bins with high insect densities, rather than fumigating all bins. This resulted in better grain management because treating bins only when insect densities exceed economic thresholds and treating only the bins that need to be treated minimises the risk of economic losses from unexpected insect problems, and reduces the cost of pest management and the use of fumigant.

External egg morphology of the most common stored-product pest mites (genera Acarus, Glycyphagus, Lepidoglyphus, Tyrophagus, Carpoglyphus, Caloglyphus), the dust mite Dermatophagoides and the predatory mite Cheyletus was studied. The comparative morphological study deals with overall appearance, size and surface sculpturing of eggs. Morphological details are illustrated with scanning electron microscope micrographs. A key for distinguishing eggs at genus level is provided. The respiratory function of some surface structures is discussed.

We have assessed a relative-humidity sensor in five storage bins equipped with temperature sensors and filled with malting barley. Three bins were aerated with ambient air and two were not aerated. The moisture content (m.c.) of grain was measured and also calculated from automatically measured relative humidity and temperature, using the modified Chung-Pfost equation and a new one, the Jacobsen equation. The Jacobsen equation gives better results than the modified Chung-Pfost equation. The greatest discrepancy was under adsorption (cooling aeration) conditions. The difference from the measured moisture content is +2.3 % m.c. to the calculated moisture content using the modified Chung-Pfost equation and +1 % m.c. using the Jacobsen equation; a gap of 1.3 % m.c..

During the past five years, Argentine farmers have faced a shortage of storage capacity and high costs of sending grain to the elevator during the harvest. In order to reduce costs and get some extra profit through grain segregation, farmers in increasing numbers are choosing to store grain in the field in 67-m long plastic "silobags", each holding around 200 tons of grain. During 2001, more than 1.5 million tons of corn, soybeans and wheat were stored this way, and it is expected in the coming years that this will increase to around 7 million tons. In January 2001 (summer) two bags were filled with wheat at 12.5% and 16.4% average moisture content. The grain was stored in the field for six months until winter. Temperature, moisture content, test weight, germination, baking quality, CO2 concentration and insect activity were the main evaluation parameters. Wheat stored at 12.5% moisture content suffered no deleterious effects in any of the quality parameters during storage. Wheat stored at 16.4% moisture content was negatively affected with respect to baking quality and seed viability. There was no increase of the grain temperature due to self-heating, and no insect activity was detected during the storage period.

The stored-grain-management group, including researchers in the Department of Biosystems Engineering, University of Manitoba and in the Cereal Research Centre, Agriculture and Agri-Food Canada was successful in obtaining 4.6 million dollars (Canadian) to construct and equip a new facility for research and development in all aspects of drying, handling, and storing grain. The major portion of the funds was provided by the Canada Foundation for Innovation, Manitoba Innovation Fund, Gateway to Future Capital Campaign, Manitoba Hydro, Agriculture and Agri-Food Canada, and the grain industry. This paper briefly describes the capabilities of the new research facility.

The relative effectiveness of propylene oxide (PPO) alone and in combination with vacuum (100-mm Hg) or 92% CO2 against all life stages of Tribolium castaneum (Herbst) during short exposure times in the laboratory was studied. Sorption of PPO by wheat, cacao bean and maize at initial concentration of 82 mg/L for a 4-h exposure was determined. All the tests were carried out in desiccators at 30 degrees C and 70% r.h. Exposures to vacuum or 92% CO2 alone, and an untreated control, were used in each test. The order of tolerance of the life stages to PPO alone was pupae > larvae > adults > eggs, these stages requiring, respectively, a concentration of 147, 84, 55 and 30 mg/L to achieve LD99 for a 4-h exposure. PPO in combination with both 100-mm Hg vacuum or 92% CO2 produced a significant decrease in the LD99 of the larvae, pupae and adults (6.2- to 7.1-fold) compared with exposure to PPO alone. There was negligible mortality of all life stages except eggs when they were exposed to 92% CO2 or vacuum (100 mm Hg) alone for 4 h. The results suggest that vacuum and CO2 have a synergistic effect on the test insects when they are exposed to PPO. Sorption of PPO by wheat, cacao bean, and maize after a 4-h exposure time varied between 57% and 79% of the initial concentration. This study suggests that combination of PPO with CO2 or vacuum could be a potential alternative to methyl bromide.

In Indian villages, many households rely for their food security on the government-sponsored Public Distribution System (PDS) that offers relatively poor quality rice or wheat at low prices. However, even in the medium term, the cost of public sector grain management to ensure food security is unsustainable. For this reason, central and state authorities in India have encouraged research into policy and practical guidelines for village-level food security. The approach being tested is to develop grain banks with groups of landless women in dryland areas of Andhra Pradesh, where the cereal staple is sorghum. These self-help groups are formed with the help of a local NGO. The research partners in this exercise are seeking to understand the situation, characteristics and needs of the village communities, recognising that any initiative in community storage should be developed through a process in which demand is established and the way of working elaborated within the group. The sustainability of this approach will become apparent over next few years. The strong emphasis on group formation and the development of appropriate systems by the group itself should encourage a high degree of "ownership" and give a greater chance of success than experienced with grain banks in the Sahel since the 1970s.

For the effective industrial use of cereal straw, the storage quality needs to be conserved over a period of 6-9 months. This study has examined the use of an automated electrolytic respirometer for quantifying the dry matter losses of cereal straw due to mixed fungal populations and individual species under different environmental conditions (0.75-0.98 water activity, a(w); 10-30 degrees C). The use of this system for screening of three different biocides for control of spoilage fungi under different environmental regimes, and for predicting levels of control, were also determined. This study has shown that dry matter losses due to fungal populations ranged up to 3.5%, while individual species on sterile straw produced up to 10% losses regardless of species used. Biocides could be effectively screened using respirometry to determine those most effective for control of fungal activity under different a, regimes. The best biocides examined could reduce dry matter loss by 50-60% at 0.95 and 0.98 a(w).

Three types of selection were used to test for the development of resistance to diatomaceous earth (DE). Insects were constantly cultured on wheat with a low dose of DE, or were constantly exposed to DE with twice the low dose but in only the top half of the wheat. In the third method of selection, adults were exposed to a high dose of DE for 10-14 days. The dose used killed some 50-80% of the population approximately every 2-3 months. Three insect species were tested: Tribolium castaneum (Herbst) (red flour beetle), Cryptolestes ferrugineus (Stephens) (rusty grain beetle) and Sitophilus oryzae (L.) (rice weevil). Constant exposures to sublethal concentrations of DE, either mixed throughout the wheat or in only the top half, did not increase tolerance to DE over a three-year period. Occasional high doses of DE that killed 50-80% of the population increased the tolerance of all three insect species tested. At the end of the three years of selection, T. castaneum had a LD50 of 1004 (831-1143) ppm (twice the control), C. ferrugineus had a LD50 of 379 (321-501) ppm (three times the control), and S. oryzae had a LD50 of 1286 (1198-1375) (four times the control). This work suggests that the method of using diatomaceous earth will affect the rate at which DE-resistant populations develop.

There is a requirement for rapid early detection of mould activity in grain throughout the food chain as part of a quality assurance programme and to enable critical control points to be effectively monitored. The rapid development of electronic-nose (e.nose) technology has resulted in examination of the potential of using this qualitative approach to enable decisions to be made about the status of grain and bakery products. Since moulds produce characteristic odours when growing on different substrates, the opportunity exists to use these volatile production patterns to improve decision-support systems for making decisions about grain quality. We have examined the use of e.nose systems for the discrimination between different grain spoilage fungi in vitro and in situ in grain. A real-time grain-monitoring system was developed which is able to evaluate a sample in less than 10 mins and give information on whether the grain is "good", "bad" or "intermediate". Subsequent studies in bakery products have shown that it is possible to detect and differentiate spoilage mould growth on bread within 24-40 h of inoculation, before visible growth. Alternative methods such as enzyme detection and colony-forming units could detect changes only much later. The use of e.nose systems as part of a HACCP scheme is discussed.

Variation among strains of Callosobruchus maculatus (F.) (Coleoptera: Bruchidae) in several life-history traits is well known. Differential respiration rates in larvae of this pest species may provide insights into how the behavioural process of larval competition within a seed produces different outcomes. Therefore, larval respiration rates in five strains of C maculatus (from Brazil, Nigeria, South India, Uganda and Yemen) were measured during their early development. Per capita consumption of cowpea seeds by larvae of the same five strains was also carried out in another bioassay. The Brazil strain is reported as having a scramble-type of outcome of larval competition and it showed the smallest respiration rate of all five strains (6.13 ml O-2/day/larva), while the strains from Uganda and Nigeria that also resemble more closely the scramble-type of competition outcome showed intermediate levels of respiration rate (7.24 and 7.34 ml O-2/day/larva respectively). In contrast, the Yemen and South India strains are reported as having a contest-type of outcome of larval competition, although the behavioural process has been determined as contest only for the South India strain. The Yemen strain of C maculatus showed the highest larval respiration rate, which did not significantly differ from the South India strain (8.39 and 7.49 ml O-2/day/larva respectively). Larvae from Yemen and South India strains also showed significantly higher per capita consumption rates of cowpea (15.15 and 11.31 mg respectively) than in larvae from the other strains (varying from 15.15 to 7.67 mg). This provides support for the hypothesis that the differential feeding rate is an important component of the larval competition outcomes observed in strains of C. maculatus.

The phase-out of methyl bromide has created a need for alternative fumigants for the treatment of stored products. One such alternative, ethyl formate (EtF), is already widely used for treatment of dried fruit in Australia. To be a viable treatment for other stored products, an allowance for the loss of EtF from the headspace during fumigation must be made in order to develop efficacious treatment schedules. There is little data on the fate of EtF during fumigation of stored products, or the mechanism of the loss from the headspace. Therefore, the fate of EtF during treatment of a number of cereals (wheat, rice, barley, oats), oilseeds (canola, sunflower, cotton), legumes (field peas, kidney beans), dried fruits (sultanas, apricots), and oaten hay was followed during fumigation under laboratory conditions at both 25 degrees and 10 degrees C. A similar study was carried out on seven rice-milling fractions. Fumigation with EtF at 25 degrees C promises to be an efficacious pest control measure in commodities where concentrations could be maintained at 60-70 g/m(3) for a period of 24 h. The high rate of loss of EtF from the headspace of fumigated paddy rice, fuzzy cotton seed, sunflower seed and kidney beans would require the application of very high dosages of fumigant to achieve headspace concentrations that would allow effective insect control in these commodities. Dried fruits, oats and wheat, field peas, oaten hay and milled rice were more promising candidates for EtF treatment. Headspace concentrations during fumigation of dried fruit were higher than during treatment of other commodities. EtF shows potential as a chemical for the protection of products that interact similarly with EtF contained in their headspace and to which the product can be applied in a similar fashion.