A new method to rapidly detect rusty grain beetle,Cryptolestes ferrugineus (Stephens), in stored grain

Information on insect infestation inside stored grain bulks is required for safe grain storage. A new method to rapidly detect both adults and larvae of Cryptolestes ferrugineus (Stephens) in grain was developed based on the principle of microwave heating and insect behaviour under elevated temperature. The designed apparatus and processing procedure were tested to extract both the adults and larvae inside wheat with 14%, 16% and 18% moisture contents by using a domestic microwave oven (referred to as the microwave method). The recovery percentage of the introduced insects associated with the microwave method was compared with that of the Berlese funnel method (810 cm³ wheat in a funnel under an incandescent light bulb). The microwave method recovered 97.8% of introduced adults, while 90.6% of adults were recovered by the Berlese funnel method. The recovery percentage of the larvae inside marked wheat kernels was 83.3 ± 3.3% with the microwave method and less than 27% with the Berlese funnel method. There was no significant difference in extraction percentage between old and young larvae when the microwave method was used. The moisture content of the treated grain did not significantly influence the extraction percentage of the pest insect. The total processing time of the microwave method was less than 30 min compared to 6 h required for the Berlese funnel method.     

A modified inclined sieve for separation of insects from wheat

An inclined sieve suitable for handling large samples of grain by one person has been developed by modification of the bag sieve used in Africa. The sieve, fabricated in aluminium, is described and its efficiency in recovering adult insects from wheat reported. Recovery of about 90% of Tribolium castaneum and Rhyzopertha dominica from 30 kg samples of wheat was achieved in 4–5 min, but recovery of Sitophilus oryzae was lower.     

Characterization of volatile organic compounds released by granivorous insects in stored wheat

Identification of the volatile organic compounds released by insects can be used to detect insects in stored grains. An attempt was made to identify the volatile organic compounds released by Tribolium castaneum (red flour beetle) and Cryptolestes ferrugineus (rusty grain beetle) by headspace analysis. Feasibility of the automatic headspace sampler in headspace analysis was found to be positive. The amount of volatiles produced by T. castaneum adults increased with an increase in insect density. The concentration of methyl-1,4-benzoquinone; ethyl-1,4-benzoquinone; and 1-tridecene released by ten adult insects were: 8.5, 9.1 and 10.6 μg/100 μL compared to 7, 8 and 4.2 μg/100 μL for five adult insects. Extreme high or low temperature leading to death produced very high amounts of volatiles compared to insects kept at 35 °C. The larvae of the T. castaneum insects did not produce any volatiles at ambient condition or at extreme cold or hot condition. The C. ferrugineus adults did not produce any detectable amount of volatiles even at very high insect density after up to 3 days. The results of the combination of T. castaneum and C. ferrugineus insects gave the same volatile compounds as produced by T. castaneum insects alone.     

Stored grain pest prevalence and insecticide resistance in Egyptian populations of the red flour beetle Tribolium castaneum (Herbst) and the rice weevil Sitophilus oryzae (L.)

As a consequence of the widespread use of insecticides against insect pests in grain warehouses and in the food industry, insecticide resistance has greatly increased among these species all over the world. Nonetheless, insecticide resistance in stored grain insects in Egypt was little studied. Therefore, our study aimed to forecast infestation risks and determine the insecticide resistance level in Egyptian populations of the main insect pests of stored grains. To achieve this goal, we surveyed the populations of stored-product insects in wheat in two different sites in the Alexandria governorate (Egypt) between June and August 2017. Moreover, insecticide resistance levels in Egyptian populations of Tribolium castaneum (Herbst) and Sitophilus oryzae (L.) collected from wheat storage facilities (granaries and flour mills) in Alexandria governorate were also determined. Three contact insecticides, namely malathion, pirimiphos-methyl and cypermethrin, were tested. Tarsal contact bioassays on filter paper were carried out on adults following FAO methods and concentration-mortality lines were estimated to determine the resistance ratios for each insecticide and population. The data from the monitoring of insects revealed that T. castaneum and S. oryzae were the most common species infesting wheat in both Alexandria granaries and mills. Populations of S. oryzae were generally more resistant to malathion than the populations of T. castaneum. However, T. castaneum populations were more resistant to pirimiphos-methyl than the S. oryzae populations. Both populations of T. castaneum and S. oryzae were susceptible to cypermethrin. The detected levels of insecticide resistance indicate that this phenomenon takes place and should be a concern in Egyptian populations of T. castaneum and S. oryzae requiring monitoring and design of resistance management practices.     

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.     

Fumigant toxicity of essential oils from three Thai plants (Zingiberaceae) and their major compounds against Sitophilus zeamais, Tribolium castaneum and two parasitoids

Fumigant toxicity of essential oils from rhizomes of Alpinia conchigera, Zingiber zerumbet, Curcuma zedoaria and their major compounds; camphene, camphor, 1,8-cineole, α-humulene, isoborneol, α-pinene, β-pinene and terpinen-4-ol was investigated with adults of Sitophilus zeamais, Tribolium castaneum, Anisopteromalus calandrae and Trichogramma deion larvae. The last two insects are parasitoids commonly used to control stored-product weevils and moths. The trial was evaluated at 0, 37, 74, 148, 296, 444, 593 μL/L in air after 12, 24 and 48 h for S. zeamais, T. castaneum and A. calandrae, and 24 h for T. deion. Alpinia conchigera oils were toxic to S. zeamais, T. castaneum and T. deion, while the other two plant oils had low toxicity. Adults of S. zeamais and T. castaneum were more susceptible to A. conchigera oils than their eggs, larvae or pupae. Sitophilus zeamais adults (LC₅₀ 85 μL/L in air) were slightly more tolerant of A. conchigera oils than T. castaneum (LC₅₀ 73 μL/L in air) after 48 h exposure. Synthetic essential oils, a mixture of pure compounds in the same ratios of the extracted essential oils, were tested with S. zeamais and T. castaneum adults. Synthetic essential oils were more toxic than the extracted essential oils to both insects. Zingiber zerumbet oils (LC₅₀ 26 μL/L in air) and C. zedoaria oils (LC₅₀ 25 μL/L in air) were significantly more toxic to adults of A. calandrae than A. conchigera oils (LC₅₀ 37 μL/L in air) whereas T. deion larvae were more sensitive to A. conchigera oils (LC₅₀ 62 μL/L in air) than Z. zerumbet and C. zedoaria oils (LC₅₀ > 593 μL/L in air). Tribolium castaneum was more susceptible than S. zeamais to the eight pure compounds. Terpinen-4-ol was highly toxic to both insects.     

Efficacy of filter cake and Triplex powders from Ethiopia against three externally developing stored product insect species

Efficacy of filter cake and Triplex powders was evaluated against the red flour beetle, Tribolium castaneum (Herbst); saw-toothed grain beetle, Oryzaephilus surinamensis (L.); and Indian meal moth, Plodia interpunctella (Hübner). Mortality of T. castaneum and O. surinamensis was determined 14 d after exposing 20 adults to 100 g of maize and wheat treated with 0, 0.3, 0.5, 0.7, 1, 2, and 3 g/kg of filter cake and 0, 0.5, 0.7, 1, 2, 3, 6, 8, and 10 g/kg of Triplex. Adult progeny production was determined at 42 d. Live larvae at 21 d and adults of P. interpunctella that emerged at 42 d were determined by exposing 100 eggs to 0, 0.2, 0.3, 0.5, 0.7, 1, 2, and 3 g/kg of filter cake and 0, 0.3, 0.5, 0.7, 1, 2, 3, 6, and 8 g/kg of Triplex treated maize and wheat. On both grains, 100% mortality of T. castaneum and O. surinamensis adults was observed after exposure to 2–3 and 1–3 g/kg of filter cake, respectively. On wheat, 100% mortality only of O. surinamensis was observed in 2–3 g/kg Triplex treatment. Adult progeny production of T. castaneum and O. surinamensis was completely suppressed on both grains treated with 0.7–3 g/kg of filter cake. Adult progeny production of T. castaneum was completely suppressed at 1–3 g/kg of Triplex treated grains, whereas complete suppression of O. surinamensis was achieved only on maize treated with 2–3 g/kg of Triplex. Both live larvae at 21 d and adults of P. interpunctella that emerged at 42 d were completely suppressed when eggs were exposed to 2–3 and 0.5–3 g/kg filter cake treated maize and wheat, respectively, and on 6–8 and 3 g/kg Triplex treated maize and wheat, respectively. Filter cake was more efficacious compared to Triplex on both grains.     

Efficacy of methoprene for multi-year protection of stored wheat,brown rice,rough rice and corn

Hard red winter wheat, brown rice, rough rice, and corn were treated with the insect growth regulator (IGR) methoprene at rates of 1.25 and 2.5 ppm, held for 24 months at ambient conditions in buckets on the floor of a grain bin, and sampled every two months. Bioassays were done by exposing 10 mixed-sex adults of Rhyzopertha dominica (F.), the lesser grain borer, and Tribolium castaneum (Herbst), the red flour beetle, on wheat, R. dominica and Sitotroga cerealella (Oliver), the Angoumois grain moth, on brown rice and rough rice, and T. castaneum and S. cerealella on corn. Sample size for all commodities was about 80 g, and these samples were held for 3 months at 27°C-60% r.h. Both rates of the IGR completely suppressed adult progeny development of R. dominica with little resulting feeding damage, sample weight loss, or insect damaged kernels (IDK). Some adult progeny production of S. cerealella and resulting IDK occurred at both rates on rough rice, brown rice, and corn, but was far less than in untreated controls. There was little adult progeny production but some feeding damage caused by larval T. castaneum in the treated wheat and corn but again far less than in untreated control. Allowing continual exposure of parental adults on grains treated with an IGR, rather than exposing those parental adults for a short time period, may give more accurate evaluations of residual efficacy. Results show that methoprene used as a grain protectant will give residual control of stored product beetles for 24 months, but complete control of S. cerealella may require inclusion of a contact insecticide.     

Effects of flameless catalytic infrared radiation on Sitophilus oryzae (L.) life stages

A laboratory benchtop flameless catalytic infrared emitter was evaluated against all life stages of the rice weevil, Sitophilus oryzae (L.), an insect species associated with stored wheat. The emitted infrared radiation was in the 3-7 μm range. A non-contact infrared thermometer measured grain temperatures continuously during exposures of infested wheat. Insect mortality was a function of the final grain temperature attained. In general, higher grain temperatures were attained when using 113.5 versus 227.0 g of wheat, and at 8.0 cm from the emitter versus 12.7 cm, and during a 60 s exposure versus a 45 s exposure. Complete mortality of all life stages of S. oryzae was achieved at 8.0 cm from the emitter using 113.5 g of wheat, with a 60 s exposure; the mean grain temperatures attained ranged from 108.4 to 111.8 °C. The log odds ratio tests showed that eggs (0 days old) were the least susceptible stage to infrared radiation, followed by adults within kernels (28 days old), pupae (24 days old), young larvae (7 days old), larvae that were 14-21 days old, and adults (42 days old). These data using small amounts of grain indicate infrared radiation from the flameless catalytic emitter to be a viable option for disinfesting wheat containing various life stages of S. oryzae.     

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.     

Susceptibility of Ethiopian wheat varieties to granary weevil and rice weevil infestation at optimal and sub-optimal temperatures

Integrating varietal resistance with temperature manipulation during storage may provide a better option for protection of stored grains and may decrease reliance on the use of synthetic chemicals. The current study was conducted to determine the susceptibility of different varieties of wheat seed to the infestation by the granary weevil, Sitophilus granarius (L.), and rice weevil, Sitophilus oryzae (L.), at optimal (30 °C) and sub-optimal (19 °C) temperatures. Kernels of six wheat varieties namely, Danda'a, Digalu, ET-13-A2, Kakaba, Millennium, and Pavon-76 were examined over a period of 90 d. Significant interactions were detected between wheat varieties and storage temperature for progeny emergence, percentage of insect damaged kernels, grain weight loss, and amount of powder produced per gram of wheat. Kernels of Danda'a, infested with S. oryzae at 30 °C exhibited significantly lower mean progeny counts (13.3 live insects), lower percentage of grain weight loss (4.2%) and insect-damaged kernels (6.4%), and powder production (1.5 mg/g). Kernel weight and hardness index were negatively associated with percentage of insect damaged kernels and grain weight loss. Kernel diameter was positively associated with both of percentage of insect damaged kernels and grain weight loss. Wheat varieties with high Zeleny sedimentation values had lower percentage of insect-damaged kernels and grain weight loss. These results indicated that kernel weight, hardness index, and protein content are predominant factors contributing to wheat resistance against S. granarius and S. oryzae. The varieties Millennium and Danda'a can be considered with other integrated pest management approaches to reduce stored grain losses of wheat in Ethiopia.     

Effect of Pisum sativum fractions on the mortality and progeny production of nine stored-grain beetles

Yellow field pea (Pisum sativum L.) fractions that were mainly protein (50%), fibre (90%) or starch (85%) were obtained from a commercial pea mill and mixed with wheat kernels or wheat flour. Based on the mortality and the number of offspring produced, protein-rich pea flour was more toxic than fibre, which was more toxic than starch. For the protein-rich pea flour mixed with wheat kernels, the most sensitive insects were Sitophilus oryzae (L.), Sitophilus zeamais Motschulsky and Sitophilus granarius (L.), followed by Cryptolestes ferrugineus (Stephens) which was more sensitive than Tribolium castaneum (Herbst) and Rhyzopertha dominica (F.). For the protein-rich pea flour mixed with wheat flour, Cryptolestes pusillus (Schönherr) was most sensitive, followed by C. turcicus (Grouvelle) and T. confusum (Jacquelin du Val), with T. castaneum being the most resistant. Although protein-rich pea flour did not kill adults to a great extent when mixed with flour, it reduced offspring production significantly. Again C. pusillus was the most sensitive, followed by T. confusum, with T. castaneum offspring being the most resistant. The insecticidal activity of pea fractions decreased after treated wheat kernels were held at 30 °C, 70% r.h. for 8 months. The potential of using pea fractions to control stored-product insects is discussed.     

Evaluation of a new insecticide formulation (F2) as a protectant of stored wheat, maize, and rice

A new commercial formulation, F2, was evaluated as a protectant of stored wheat, stored maize, and stored rough (paddy) rice. This formulation comprises the technical active ingredients 0.03% deltamethrin, 0.37% piperonyl butoxide, and 0.95% chlorpyriphos-methyl, plus 10% mineral oil and 88.0% of the diatomaceous earth Protect-It^®. Tests were conducted with dust and slurry formulations at 50 and 100 ppm, 57% and 75% relative humidity, and 22°C, 27°C, and 32°C. On wheat, survival of the lesser grain borer, Rhyzopertha dominica (F.), ranged from 0% to 30.0%, survival of the rice weevil, Sitophilus oryzae (L.), was 0-6.2%, and survival of the red flour beetle, Tribolium castaneum (Herbst), was 0-97.5%. Few F₁ adults of any of the three species were found in the treated samples. Survival of the maize weevil, Sitophilus zeamais (Motschulsky), on treated corn was 0-32.5%, while survival of T. castaneum was 0-88.7% in the 50-ppm dust and slurry treatments, and 0-51.4% in the 100-ppm treatments. Again, few F₁ adults of either species were found in treated maize. Survival of R. dominica on treated rough rice averaged 0-4.1% and survival of S. oryzae on treated rice was 0-48.8%, but the majority of weevils that survived were in one replicate. F₁ adults in the treatments ranged from 0 to 24.4. Results show that the combination insecticidal product F2 was extremely effective on all three commodities at the rate of 100 ppm, as either a dust or slurry, and could be used as a commodity protectant.     

Feasibility of protein fingerprinting technology for detecting Tribolium castaneum (Herbst) insect fragments in wheat flour

The red flour beetle, Tribolium castaneum (Herbst), is one of the predominant insects that cause serious decrease in quality of wheat flour. Protein mass fingerprinting has the potential to accurately detect insect parts in wheat flour, based on special peptides of T. castaneum. For determining the capability of protein fingerprinting for detecting insect parts in wheat flour, T. castaneum, wheat flour, and mixtures of T. castaneum and wheat flour were tested in this study. Three protein extraction buffers: 50% acetonitrile; sterilized water; and the buffer of 10 mM imidazole pH 7.0, 1 mM phenylthiourea, 1% Triton X-100 and protease inhibitor cocktail (PTU buffer), were compared for insect protein detection. An Agilent 1100 reversed phase high performance liquid chromatography (RP-HPLC) instrument was used for peptide purification and fractionation. Matrix-assisted laser desorption/ionization (MALDI) was used to read the RP-HPLC fractions, and the results were analyzed using sMART Engine, details given later. Fifty percent acetonitrile was adopted as protein extract buffer. Since very limited information about T. castaneum protein can be found in the database of sMART and National Center for Biotechnology Information (NCBI), peptide mapping method was used for identifying insect from the wheat flour. Peptide mapping method, which could set up biomarkers for each type of insect, was proven to be a more effective and practical way to detect insect contamination. This peptide mapping technique could obtain 78 biomarkers of T. castaneum, when T. castaneum was 0.1% in wheat flour by mass. This sensitivity needs to be increased further during future research.     

Insect population dynamics in commercial grain elevators

Data were collected in 1998-2002 from wheat stored in commercial grain elevators in south-central Kansas. Bins at these elevators had concrete walls and were typically 6-9 m in diameter and 30-35 m tall. A vacuum-probe sampler was used to collect grain samples in the top 12 m of the wheat in each bin. The primary insect species found in the wheat samples were: Cryptolestes ferrugineus, Rhyzopertha dominica, and Tribolium castaneum. In the top 3.7 m of grain, R. dominica, C. ferrugineus, T. castaneum and Sitophilus oryzae made up 44, 36, 19 and 1% of the insects found in the samples, respectively. From 3.8 to 12.2 m, R. dominica, C. ferrugineus, T. castaneum and S. oryzae were present at 84, 8, 8, and 1%, respectively. The most prevalent species also changed over time. In June, the start of wheat harvesting and storage in Kansas, insect density was low in the bins. At this time, C. ferrugineus was the most common insect, and it was found mostly in the top grain sample (0-1.2 m). In September through November, C. ferrugineus and R. dominica were at similar densities; however, from February to March, R. dominica was more common.Generally, insect density was greatest at the top and decreased with grain depth. Very few insects were found in samples collected from greater than 12 m (most of the bins contained grain to depths of 24-36 m). Insect density for all species increased rapidly from June through October. During this period less than 20% of the bins had economically significant insect densities (>2 insects/kg). From October until February, the average insect density remained fairly constant but it was greatly reduced in April, May, and June. Bins that had insect densities >2 insects/kg tended to be located adjacent to other heavily infested bins.     

Comparative gamma radiation sensitivity of Tribolium madens (Charpentier) and T. castaneum (Herbst)

The effects of gamma radiation doses between 5 and 100 krad on all metamorphic stages of Tribolium madens and T. castaneum were studied. Results from the two species were similar although T. madens appeared to be more radiosensitive. The development of adults from treated eggs and larvae was prevented by 5 krad in T. madens and by 10 krad in T. castaneum. Some adults emerged from treated pupae at all treatment levels, but no reproduction occurred at 20 krad or above. Adult females of both species were more sensitive to the sterilizing effects of gamma radiation than were males, but sterility of both sexes was effected at doses of 30 krad and above. Control of these two species appears feasible with levels of radiation currently approved for treatment of stored-grain insects in wheat and wheat flour.     

Comparative performance of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) across populations,resource types and structural forms of those resources

The significance of Tribolium castaneum (Herbst) as a pest of stored grains will likely be influenced by the relative availability of different resources regionally and the beetles’ ability to utilize each of them. Therefore the performance across the life cycle of laboratory and field populations of T. castaneum on commonly available structural forms of wheat and sorghum, as conventional resources, was quantified and compared to that on cotton seed. The latter is not usually associated with T. castaneum, but large beetle infestations have been recorded commonly in cotton gins in Australia. The highest number of individuals of each stage (from a given number of eggs) developed on wheat and sorghum flour and kibbled seeds. Cotton seed did not support the development of laboratory population beetles and all neonate larvae died before pupation. In contrast, some of the field population larvae did develop on cotton flour, but their number was significantly lower in comparison to development on wheat and sorghum. Field population beetles produced significantly more eggs than did laboratory population beetles, on both the whole seed and flour. Field population females had a consistently higher fecundity (～78% more eggs) than the laboratory population females, at least over the first three weeks of adult life. These results suggest that field populations of T. castaneum should be used in experiments if we are to develop a more realistic understanding of the field ecology of this species. The relative rate at which these insects infest available resources in the field also warrants further investigation.     

Evaluation of potential use of nootkatone against maize weevil (Sitophilus zeamais Motschulsky) and rice weevil [S. oryzae (L.)](Coleoptera: Curculionidae)

Nootkatone is a natural sesquiterpene ketone that shows insecticidal activity against insects and ticks. Its contact toxicity and repellency against two major stored-product insect pests, maize weevil (Sitophilus zeamais Motschulsky) and rice weevil [Sitophilus oryzae (L.)], were investigated in the current study. Contact toxicity was evaluated using a no-choice test with treated filter paper, while repellency was evaluated using a choice test with treated corn (for maize weevils) or wheat (for rice weevils). Nootkatone showed low contact toxicity (ranging from 0 to 51%) against the two weevil species at the tested concentrations (ranging from 11.58 μg/cm² to 1158.08 μg/cm²) on filter papers. In choice tests, corn treated with 0.10% or higher and wheat treated with 0.5% nootkatone or higher had significantly fewer maize or rice weevils compared with the solvent only treated control, indicating a repellent effect. The repellency percentage ranged between 46.3 and 93.1% against maize weevils and 39.2-67.2% for rice weevils.     

Influence of temperature and application rate on efficacy of a diatomaceous earth formulation against Tribolium castaneum adults

Unsanitary storage bins can harbor grain-infesting insects, including the red flour beetle, Tribolium castaneum (Herbst). In a previous study involving heat treatment of empty bins, temperatures in the range of 50–55 °C for 2–4 h were effective in completely killing stored-product insects. Previous research in flour mills showed improved efficacy in killing stored-product insects by using diatomaceous earth (DE) dusts at temperatures below 50 °C. In the current study, the efficacy of a diatomaceous earth formulation (DiaFil^® 610) applied to concrete arenas, to simulate floor of empty bins, was examined at three application rates (0, 2.5 and 5.0 g/m²) to control T. castaneum adults at five constant temperatures (28, 36, 42, 44, and 46 °C). Ten adults of T. castaneum were placed on individual untreated and DE-treated concrete arenas for 4, 8, 12, and 24 h at each of the five temperatures. The efficacy of DE against T. castaneum adults increased with an increase in temperature and exposure time. Generally more adults died at 5.0 g/m² when compared with 2.5 g/m². In 2.5 and 5.0 g/m² DE treatments, exposure for 12 h at a temperature of 42 °C resulted in 73–77% mortality of adults with 100% mortality observed after 24 h. At 44 and 46 °C, 100% mortality of adults was observed after 24 h of exposure at both DE rates. At these two temperatures, the high mortality in untreated arenas (controls) at 8, 12, and 24 h exposures ranged from 27 to 100% confounding the true effects of DE. Our results suggest that combined use of DE and temperatures below 50 °C can be used as an integrated approach for controlling insects in empty bins prior to storage of newly-harvested grain.