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.     

Simulation model of Rhyzopertha dominica population dynamics in concrete grain bins

Rhyzopertha dominica is one of the most damaging insect pests in grain elevators and causes millions of dollars worth of stored grain losses annually in the USA. A simulation model was developed for predicting R. dominica population dynamics in concrete grain bins. The model used a two-dimensional representation of a cylindrical concrete bin (33 m tall×6.4 m wide), and used hourly weather data to predict changes in grain temperature. Output from the grain bin temperature and moisture module was used by the insect module to predict changes in insect density in 32 different bin regions. When compared to validation data from nine grain bins, the model accurately predicted insect vertical distribution and insect density. In December, the highest insect density was in the top center of the grain mass, and decreased steadily with increasing depth and towards the periphery of the grain mass. R. dominica attains this spatial distribution because immigration is primarily through the top of the bin, and higher populations occur in the interior of the grain mass because of warmer temperatures there. Initially, the model underestimated actual insect density in the grain bins. We increased the immigration rate by 50% and this resulted in a much better prediction of R. dominica density by the model. From 20 September to 14 December, populations of R. dominica increased from 0.1 to 3.5 insects per kg of wheat.     

Protection of stored maize from insect pests using a two-component biological control method consisting of a hymenopteran parasitoid, Theocolax elegans, and transgenic avidin maize powder

The hymenopteran parasitoid, Theocolax elegans (Westwood), and transgenic avidin maize powder were tested to determine if their individual or combined use would protect stored grain from infestation by both internal and external insect pests. Small-scale tests were conducted in plastic jars containing 3 kg of non-transgenic maize. We tested treatments of 0.3% powdered avidin maize, the parasitoid wasp, and the combination of the parasitoid plus 0.3% powdered avidin maize. One pair each of Sitophilus zeamais Motschulsky, Tribolium castaneum (Herbst), and Cryptolestes ferrugineus (Stephens) was added to each jar. After 8 weeks, the entire contents of each jar were examined for adult insects. Control and avidin maize powders had no detrimental effects on the beneficial insect parasitoid T. elegans. The parasitoid suppressed populations of the internal feeder S. zeamais. The avidin maize powder treatment had no effect on S. zeamais because these larvae developed inside the maize kernels where no avidin maize powder was present. For S. zeamais, the combination treatment was not significantly different from the parasitoid treatment. In contrast, populations of the external feeder T. castaneum were not suppressed by the parasitoid but were suppressed by the avidin maize powder treatment. The parasitoid-avidin combination treatment produced the greatest percentage reduction for all three insect species and resulted in 78%, 94%, and 70% reductions in populations of S. zeamais, T. castaneum, and C. ferrugineus, respectively, when compared to the control treatment. The percentage reductions for the parasitoid treatment were 70%, 8%, and 20% for S. zeamais, T. castaneum, and C. ferrugineus, respectively. For the avidin maize powder treatment, populations of S. zeamais, T. castaneum, and C. ferrugineus were reduced by 10%, 85%, and 40%, respectively. The combination treatment of avidin maize powder plus the release of parasitoid wasps was superior to either treatment alone when applied to mixed populations of internal and external feeders.     

A simple technique to assess compounds that are repellent or attractive to stored-product insects

We have developed a simple and rapid technique that mimics storage conditions, and determines if products are repellent or attractive to stored-product insects. The technique determines the response of insects to potential repellents and attractants by measuring their movement from grain. The technique used a device consisting of a perforated cup (2 mm perforations) that holds 200 g of wheat. A Petri dish and cup collected the insects as they left the wheat. Several natural products were tested for repellency: diatomaceous earth (DE), ground peas (Pisum sativum), protein-rich pea flour, pea starch, and pea fibre. Adult insects of three species were tested: the rice weevil, Sitophilus oryzae, the red flour beetle, Tribolium castaneum, and the rusty grain beetle, Cryptolestes ferrugineus. DE at 0.01% was repellent to all insects tested. Pea fibre, pea protein, and ground pea at 1% caused increased emigration of C. ferrugineus from the wheat. Pea starch did not affect movement out of the grain for all three insects. Only pea fibre and ground pea increased the movement of T. castaneum out of the grain. For S. oryzae, there were no differences after 1 h, but after 24 h both pea protein and ground pea increased movement out of the grain. Several potential attractants were placed outside the grain and the emigration out of the grain noted. For R. dominica, the commercial R. dominica pheromone increased the emigration of insects from the grain; R. dominica adults on broken grain enclosed in a ventilated vial in the collection jar also increased emigration, but not as much as the synthetic pheromone. The commercial Tribolium pheromone did increase movement out of the grain for T. castaneum, but the other treatments were no different from the control. None of the potential attractants increased the movement of S. oryzae from the grain. The implications of this work are discussed with reference to controlling and sampling stored-product insect pests.     

Interspecific associations among stored-grain beetles

Recent increases in prices of raw grain, including wheat, will reduce action thresholds for insect damage and therefore justify more research into management practices and understanding of pest ecology in stored grain. Compared to most other habitats, natural or man-made, a filled grain silo constitutes a unique and fairly homogeneous habitat in which food availability for many grain-feeding insects is unlimited. A fundamental aspect of stored-grain insect ecology is a better understanding of associations among common beetle species. We analyzed the densities of three important stored-grain beetle species, Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae), and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) in wheat samples collected in 1999–2001 from 129 grain silos in Kansas. The beetles studied here are highly mobile, and the number of insects in each grain sample is a result of the beetles' preference for favorable micro-environmental conditions and possibly of intra- and interspecific associations. In general, the number of T. castaneum in a grain sample increased as the number of R. dominica increased, but the number of C. ferrugineus was not correlated with the number of R. dominica. The densities of both T. castaneum and R. dominica decreased as the number of C. ferrugineus increased. Cryptolestes ferrugineus and T. castaneum can be predators and the species composition of insects in a grain sample may be modified by predation. As T. castaneum populations increased, so did R. dominica but not C. ferrugineus. Our analysis of the species composition in grain samples is discussed in an ecological context.     

Heat treatment for disinfestation of empty grain storage bins

An alternative to fumigants and insecticides for controlling stored-product insects in empty grain storage bins prior to filling is heat treatment, in which the temperature is quickly raised to a minimum of 50 °C and held there for 2-4 h. Effectiveness of heat treatment on empty grain storage bins was evaluated for five commercial propane and electric heat-treatment systems by measuring air temperature and associated mortality of Tribolium castaneum (Herbst), the red flour beetle, Sitophilus oryzae (L.), the rice weevil, and Rhyzopertha dominica (F.), the lesser grain borer, exposed for different time intervals. Eleven locations, six above and five below the drying floor, were monitored for air temperature and associated mortality of the three insect species, using arenas initially stocked with live adult insects. Data were analyzed separately for each heating system, with floor location and time interval as main effects for insect mortality. A high-output propane heater (29 kW) produced 100% mortality in 2 h for the three insect species at all test locations. An electric duct-heater system (18 kW) also produced 100% mortality at all test locations after 40 h when aided by a complicated interior heat-distribution system. The other three systems produced less than 100% mortality.     

Survival and reproduction of Tribolium castaneum (Herbst), Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) following periods of starvation

This study determined the starvation tolerance of Tribolium castaneum (Herbst), Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) in terms of both adult survival and reproduction, the impact of starvation on reproduction not having been studied before. Experiments were conducted at 30 °C and 55% or 70% r.h. using a laboratory strain and a field strain of each species. The number of progeny was a better indicator of the impact of starvation on a species than adult survival. Tribolium castaneum was the most tolerant species, requiring up to 35 d starvation before no progeny were produced. Rhyzopertha dominica and S. oryzae required up to 8 d starvation before no progeny were produced. The results suggest that hygiene will have a greater impact on populations of S. oryzae and R. dominica than T. castaneum.     

Effect of suboptimal temperatures and sublethal CO2 levels on multiplication of Tribolium castaneum (Coleoptera: Tenebrionidae), alone or competing with Cryptolestes ferrugineus (Coleoptera: Cucujidae)

Groups of adults of Tribolium castaneum alone, or in combination with adults of Cryptolestes ferrugineus, were exposed to suboptimal temperatures (15°C, 20°C, and 25°C) and sublethal CO₂ levels (2%, 5%, and 10%) in dry (12%, wet mass basis) and damp (15%, wet mass basis) stored wheat in the laboratory, to investigate effects on population size. The mean adult numbers in single- and mixed-species tests were positively correlated with higher temperature and moisture content and negatively correlated with higher CO₂ levels. Adult numbers in single- and mixed-species tests were lower at sublethal CO₂ levels compared to ambient CO₂ levels at all the test temperatures and decreased in dry grain compared to damp grain. Although, a specific trend was not observed in population inhibition between mixed-species and single-species tests, overall the adult populations of T. castaneum were reduced in the presence of C. ferrugineus. A mathematical model was derived to predict the size of adult populations of T. castaneum alone, or in the presence of C. ferrugineus considering all the variables in this study. The model had an R² value of 0.72 but needs to be validated and refined with field data.     

Laboratory assessment of insecticidal effectiveness of natural zeolite and diatomaceous earth formulations against three stored-product beetle pests

The insecticidal effectiveness of two natural zeolite formulations (Minazel plus and Minazel), applied to wheat at selected rates of 0.25, 0.50 and 0.75 g/kg, and a diatomaceous earth formulation (DE) (Protect-It™), applied at the recommended rates of 0.15 g/kg for Sitophilus oryzae, 0.20 g/kg for Rhyzopertha dominica and 0.30 g/kg for Tribolium castaneum, were tested under laboratory conditions (24 ± 1 °C temperature and 45 ± 5% relative humidity). The highest adult mortality was observed after the longest exposure period of 21 days and 7 days of recovery, when all three zeolite dosage rates and the recommended DE dosage caused 97-100% mortality of S. oryzae and 94-100% of T. castaneum. On the other hand, 100% mortality was not achieved in any test variant involving R. dominica; the highest (about 92%) was detected for DE, while 52% and 79% mortality was achieved with the zeolites at the highest rate of 0.75 g/kg. Progeny reduction by >90% was achieved after 21 days of contact of all three beetle pests with DE-treated wheat, while the same level of reduction was achieved for S. oryzae and T. castaenum only after contact with the highest rate of the zeolite product, Minazel. Thus the two zeolite formulations are comparable to diatomaceous earth in controlling adult S. oryzae, R. dominica and T. castaneum, but only the Minazel formulation could effectively protect wheat from attack by S. oryzae or T. castaneum, and only with a higher rate of application than for the DE formulation.     

Movement of Rhyzopertha dominica in response to temperature gradients in stored wheat

The movement and temperature preference of Rhyzopertha dominica was determined in a 56 cm diameter cylinder with 9 cm high sides containing 19.9 kg of hard red winter wheat. Two temperature gradients were tested over a 24 h period: 42 to 20 °C and 24 to 20 °C with the cooler temperature being on the periphery of the cylinder. No preference existed when there was no temperature gradient. Beetles preferred the moderate temperature region of the cylinder in the 42 to 20 °C gradient, but avoided the highest temperature region. In the 24 to 20 °C gradient, insects did not move very much during the 24 h period. When a longer duration was used (96 h) for the 24 to 20 °C gradient, there were significantly more insects in the warmest center region of the gradient compared to the middle or outer regions. Compared to other stored grain Coleoptera, such as Cryptolestes ferrugineus, R. dominica appears to move more slowly through the grain into preferred temperature regions.     

Developmental and population growth rates of phosphine-resistant and -susceptible populations of stored-product insect pests

Phosphine resistance positively contributes towards an individual's fitness under phosphine fumigation. However, phosphine resistance may place resistant individuals at a fitness disadvantage in the absence of this fumigant, which can be exploited to halt or slow down the spread of resistance. This study aimed to determine if there is a fitness cost associated with phosphine resistance in populations of the red flour beetle (Tribolium castaneum (Herbst)), the lesser grain borer (Rhyzopertha dominica (F.)) and the sawtoothed grain beetle (Oryzaephilus surinamensis (L.)). The developmental rate and population growth of phosphine-resistant and -susceptible populations of these three species of stored-product insects were therefore determined under phosphine-free environment. The majority of the phosphine-resistant populations exhibited lower developmental and population growth rates than the susceptible populations indicating that phosphine resistance is associated with fitness cost in all three species, which can potentially compromise the fixation and dispersal of the resistant genotypes. Nonetheless, some phosphine-resistant populations did not show a fitness cost. Therefore, resistance management strategies based on suppression of phosphine use aiming at eventual reestablishment of phosphine susceptibility and subsequent reintroduction of this fumigant will be useful only for insect populations exhibiting a fitness cost associated with phosphine resistance. Therefore recognition of the prevailing phosphine-resistant genotypes in a region is important to direct the management tactics to be adopted.     

Movement and distribution of adult Cryptolestes ferrugineus (Coleoptera: Laemophloeidae) in stored wheat in response to temperature gradients, dockage, and moisture differences

The movement and distribution of adult Cryptolestes ferrugineus were determined in 100×100×1000 mm wheat columns with or without 5 °C/m temperature gradients (from 27.5±0.2 to 32.5±0.2 °C or at 27.5±0.2 °C) under: (1) 5% and 10% uniform dockage (14.5±0.2% moisture content (m.c.), wet basis); (2) half of the columns with 5% or 10% dockage and the other half without dockage; (3) 12.5%, 14.5% or 16.5% m.c. wheat without dockage; and (4) half of the columns with 12.5% or 14.5% m.c. wheat and the other half with 16.5% m.c. wheat.Adults introduced in the middle of the horizontal wheat columns with or without uniform dockage showed no bias in the direction of net displacement, with the distribution pattern gradually becoming more uniform when time increased from 1 to 144 h. In vertical columns with 0%, 5% and 10% uniform dockage, the adults preferred to move down in the first 24 h; however, they moved up after 24 h. Grain with a high percentage of dockage (10%) decreased beetle movement speed. A low percentage of dockage (5%) did not influence insect movement and distribution. Positive geotaxis was more important than the attraction of dockage.Adults responded to both temperature gradients and moisture differences in columns of wheat with temperature gradients and moisture content differences. The response was different at different moisture conditions. Adults were more sensitive to moisture differences and moved faster in 12.5% m.c. wheat than in 14.5% m.c. wheat. Adults stayed in warmer sections in both high and low moisture grain. At different moisture conditions, adults changed their preference (e.g., preferred high moisture grain in dry grain, and preferred warmer temperature in damp grain).     

Efficacy of diflubenzuron plus methoprene against Sitophilus oryzae and Rhyzopertha dominica in stored sorghum

The efficacy of diflubenzuron (1 mg kg⁻¹)+methoprene (1 mg kg⁻¹) against Sitophilus oryzae (L.) and Rhyzopertha dominica (F.) in sorghum was evaluated in a silo-scale trial in southeast Queensland, Australia. Sorghum is normally protected from a wide range of insects by mixtures of grain protectants. The chitin synthesis inhibitor diflubenzuron was evaluated as a potential new protectant for S. oryzae in combination with the juvenile hormone analogue methoprene, which is already registered for control of R. dominica. Sorghum (ca 200 t) was treated after harvest in 2000 and assessed for treatment efficacy and residue decline during 6.5 months storage. The reproductive capacity of S. oryzae and R. dominica was greatly reduced in bioassays of treated sorghum throughout the trial, and efficacy remained relatively stable during the trial. An initial exposure of S. oryzae adults to treated sorghum for 2 weeks reduced F₁ progeny production of all strains by 80.8-98.8%, but a second exposure of 4 weeks reduced F₁ progeny production by 98.5-100%. In addition, the reproductive capacity of any S. oryzae progeny produced was greatly reduced. Exposure of R. dominica adults to treated sorghum for 2 weeks reduced F₁ progeny production of all strains by 99.6-100%, including a methoprene-resistant strain. The results indicate that S. oryzae or R. dominica adults invading sorghum treated with diflubenzuron (1 mg kg⁻¹)+methoprene (1 mg kg⁻¹) would be incapable of producing sustainable populations.     

Temperature-mediated functional response of Theocolax elegans (Hymenoptera: Pteromalidae) parasitizing Rhyzopertha dominica (Coleoptera: Bostrichidae) in stored wheat

The functional response of Theocolax elegans (Westwood) parasitizing the lesser grain borer, Rhyzopertha dominica (F.) was examined over a range of temperatures. A type II functional response equation was fitted to each temperature regime. The parasitization rate was highest at 30°C (20 hosts per day) and was lowest at 20°C (2 hosts per day). Handling time was inversely proportional to temperature, and ranged from 1.6 days at 20°C to 0.05 days at 30°C. Instantaneous search rate also changed with temperature. It was lowest at 20°C and highest at 30°C. A temperature-mediated functional response equation was fitted to the data, in which handling time was a quadratic function of temperature. The equation explained 74% of the variance in parasitization rate. Theocolax elegans has a narrower optimal temperature range than other parasitic stored-product Hymenoptera. Temperatures greater than 32.5°C caused high parasitoid mortality.     

Effectiveness of a multi-species attractant in two different trap types under practical grain storage conditions

Commodities may be attacked by a multitude of pest species simultaneously and so to be cost-effective any lure must be attractive to a range of target species. The objective of this study was to test a multi-species lure formulation with different dispensers under conditions as close as possible to their use in practice. The attractant effect of the multi-species lure formulation was tested using two types of dispensers with populations of the three principal grain beetle pests in the UK (Oryzaephilus surinamensis, Sitophilus granarius and Cryptolestes ferrugineus). The trials were performed over a period of six weeks with the lures tested in PC™ Traps: first in a grain bulk and in six grain bins and second in the surrounding area using PC™ Floor Traps. The amounts of volatiles released in and around in situ traps were measured using Solid-Phase Microextraction (SPME).The first lure dispenser tested was attractive to O. surinamensis and C. ferrugineus but it attracted fewer S. granarius than the control traps. It was shown that most of the volatiles were released at the beginning of the trial and therefore lures were not effective over the whole six-week period. The second lure dispenser released the attractant volatiles more consistently over six weeks and exerted significant attraction to O. surinamensis and C. ferrugineus in PC™ Traps in the grain bulk and to O. surinamensis and S. granarius in floor traps. Too few C. ferrugineus were caught in floor traps to make a comparison. The reason for the repellent effect on S. granarius in the grain bulk was unclear and this is discussed along with the importance of measuring volatiles released by the lure.     

Temperature variation in stored maize and its effect on capture of beetles in grain probe traps

Seasonal and spatial distribution of Typhaea stercorea (L.) and Tribolium castaneum (Herbst) infesting farm-stored maize in South Carolina were studied by trapping with grain probe traps. Trap catch (numbers captured per week) and weekly mean grain temperature for each trap site were plotted against time and fitted to cubic polynomials, which adequately described seasonal trends. Spatial distribution of trap catch was examined by calculating the coefficient of variation, or dispersion (s²/m) and by constructing a contour map of trap catch values for each week. Seasonal trends in trap catch varied with species, farm, and storage season, and tended to parallel temperature trends, so that trap catch and temperature were positively correlated. Trap catch was highly aggregated except for weeks when few insects were captured. Residuals (observed-predicted values), calculated from the fitted trend curves, represent the spatial component of variation. When residuals were analyzed, the positive correlation between temperature and trap catch was usually reduced or abolished, indicating that spatial variability within any given week reflected the distribution of the population itself, rather than spatial variability in activity produced by temperature gradients. The number of insects captured by a trap is determined mainly by insect activity and the numbers present, but there are no rigorous methods for separating the immediate effect of temperature on activity from the delayed effect on population growth. However, by comparing trends in trap catch with those in temperature, it is sometimes possible to make inferences about changes in population density.     

Detection of Rhyzopertha dominica larvae in stored wheat using ELISA: The impact of myosin degradation following fumigation

Hard red winter wheat kernels were infested with eggs of Rhyzopertha dominica. After 20 d, when the larvae reached the fourth instar, they were killed by exposing the infested kernels to phosphine gas for 24 h. The infested kernels were then divided into four portions and treated as follows: one portion was immediately frozen at −80 °C to avoid myosin degradation; the other three portions were kept at 32 °C and 65% relative humidity, and then frozen at −80 °C after 14, 28, and 56 d post-fumigation, respectively. Each treatment was replicated five times. Myosin was measured using a commercial enzyme linked immunosorbent assay (ELISA) method that specifically detects this protein (Biotect^®, Austin, TX). Myosin degradation was most rapid in the first 2 weeks after the larvae were killed, decreasing from 1.672 to 0.695 ng/well during this period (a 58.4% reduction). There were no significant differences in myosin degradation between samples that were 14, 28, and 56 d post-fumigation. Grain is often fumigated to control insects. Frequently, this occurs many weeks before the grain is milled and may be repeated during the storage period. Therefore, estimates using the ELISA test may underestimate internal insect infestation because of myosin degradation. Insect fragment estimates for previously fumigated grain could be underestimated by as much as 58%.     

Integrated management of insect vectors of Aspergillus flavus in stored maize, using synthetic antioxidants and natural phytochemicals

The purpose of this study was to investigate the insecticidal activity of two benzoic acids 2(3)-tert-butyl-4 hydroxyanisole (BHA) and 2,6-di(tert-butyl)-p-cresol (BHT); two phenolic acids 3-phenyl-2-propenoic acid (CA) and trans-4-hydroxy-3-methoxycinnamic acid (FA) and two essential oils of Eugenia caryophyllata (clove tree) and Thymus vulgaris (thyme) against Sitophilus zeamais, Tribolium confusum and Rhyzopertha dominica, vector carriers of aflatoxigenic fungi in stored maize. The susceptibility of insects, the frequency of isolation of Aspergillus section Flavi in insects and maize, and the analysis of aflatoxin B₁ in maize were determined. BHA, BHT, BHA/BHT mixture and the natural phytochemicals AF and AF/AC mixture showed the highest insecticidal activity against S. zeamais, T. confusum and R. dominica after 120 days of incubation. The insecticidal efficacy of the volatile fraction of essential oils of clove and thyme showed less inhibition. There was no contamination of Aspergillus section Flavi in dead and live insects collected from maize treated with BHA. No aflatoxin B₁ accumulation was detected in the control and treatments. The information obtained shows that these substances have the potential to control pest insect vectors of aflatoxigenic fungi in stored maize in microcosms during 120 days.     

Toxicity of ethyl formate to adult Sitophilus oryzae (L.), Tribolium castaneum (herbst) and Rhyzopertha dominica (F.)

Fumigations were conducted using a continuous flow-through laboratory process to maintain constant concentrations of ethyl formate and low levels (<0.8%) of respiratory carbon dioxide. The procedure minimised the effects of sorption by exposing test insects without media and minimised the effect of carbon dioxide by use of continuous flow. The concentration×time (Ct) products of ethyl formate for adult Sitophilus oryzae, Tribolium castaneum and Rhyzopertha dominica at 25 °C and 70% relative humidity for the 6 h exposure were, respectively: (1) LD₅₀ 107.8, 108.8 and 72.8 mg h L⁻¹ and (2) LD_99.5 207.4, 167.1 and 122.2 mg h L⁻¹. Endpoint mortality was reached within 24 h of initial exposure.     

Grain loss caused by Tribolium castaneum, Sitophilus oryzae and Acanthoscelides obtectus in stored durum wheat and beans treated with Beauveria bassiana

The effect of the fungal entomopathogen Beauveria bassiana (Balsamo) Vuillemin (Hyphomycete) on the losses caused to durum wheat and beans by storage insects was investigated. Grains were infested with Tribolium castaneum (Herbst), Sitophilus oryzae (L.) and Acanthoscelides obtectus (Say). Beauveria bassiana was produced in inoculated autoclaved rice. The spore formulation (ground rice and B. bassiana) was applied to grain (wheat or bean) and shaken to evenly cover the grain. Adults of T. castaneum or S. oryzae were added to wheat and adults of A. obtectus to bean. Five replicates were set up for each treatment and controls (milled rice but no conidia). The insecticidal effect of B. bassiana was tested by measuring the fresh weight and weight loss of grains after four months of storage. Wheat grains infested with S. oryzae without the conidia was significantly more damaged by weevils than grains treated with B. bassiana. The mean fresh weight of grains with the conidia was significantly greater (18.4%) than the corresponding mean without the fungus when S. oryzae were present. Percentage weight loss decreased by 81.5% and was significantly smaller than the loss from the untreated grain. Significant differences were not found in the fresh weight of seed infested with T. castaneum or A. obtectus in treated or untreated grain nor in the percentage weight loss of grains infested with these insects, with and without B. bassiana.