Stored-product Species Research Articles

Population growth of different stored product species on wheat, barley, and tritordeum

Stored product species can be developed in a variety of stored product grains. In this study, were compare three different grains for their suitability for population growth of primary and secondary stored product insects. In the first series, we evaluated the population growth and damage of Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), Sitophilus granarius (L.) (Coleoptera: Curculionidae) and Sitophilus oryzae (L.) (Coleoptera: Curculionidae) on whole wheat, barley and tritordeum kernels after 65 days. In the second series, three different percentages of whole and cracked kernels were tested: 100% cracked kernels, 100% whole kernels and 50% cracked +50% whole kernels, for Oryzaephilus surinamensis (L.) (Coleoptera: Silvanidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The results showed that tritordeum was suitable for the population growth of all species tested. In most of the cases, R. dominica showed higher frass production but S. granarius showed a higher number of damaged kernels. Cracked kernels were preferred by secondary pests than whole kernels and wheat showed the highest progeny production than tritordeum and barley. Overall, commodity, and grain type and percentage of cracked kernels can affect the population growth of stored product insect species. Results of this study showed that stored product insect species can develop in tritordeum and thus should be taken into consideration for further results as may be damaged during storage.

Persistence and efficacy of diatomaceous earth against stored product insects in semi-field trials

The utilization of inert dusts, such as diatomaceous earths (DEs), has been successfully evaluated against a wide range of major stored-product pest species, as an environmentally friendly alternative to conventional insecticides, emphasizing further their prominent position in Integrated Pest Management (IPM) protocols. However, the majority of the published research about the DEs’ insecticidal efficacy has been conducted under laboratory conditions in small-scale samples (usually in small vials containing few grams of grains) and against specific insect species, while field and semi-field applications for the same purpose are disproportionally few. The objective of this work was to evaluate the insecticidal activity of a commercial DE formulation against stored product species that either artificially or naturally infested hard wheat, under “real-world” storage conditions. For this purpose, DE doses of 0 (control), 500 and 1000 ppm were applied in a series of lots of 20 kg of hard wheat stored in polypropylene woven bags and kept from August to December in a storage facility in Central Greece. According to our results, even the lower DE dose significantly suppressed the insect populations of Sitophilus oryzae (L.) (Coleoptera: Curculionidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Trogoderma granarium Everts (Coleoptera: Dermestidae) that were artificially added in the wheat bags but also of five other insect pest species that were found in the commodity, based on weekly monitoring via probe traps or grain samples. Rhyzopertha dominica, T. granarium and S. zeamais were the most numerous species found, while T. granarium was the most frequently sampled species. In general, the probe traps were more sensitive to captures, as compared to the grain samples. The evaluation of the grain quality (bulk density, insect damaged kernels) throughout the trials indicated higher insect infestations in the untreated wheat as compared to the treated one. At the same time, grain bulk density was lower in the treated than in the untreated wheat. We conclude that DE applications can effectively suppress the populations of a wide range of stored insect species, offering a prolonged protection under a wide range of environmental conditions.

The dispersal ability of the invasive larger grain borer and the cosmopolitan maize weevil after brief exposure to a newer insecticide formulation

The larger grain borer (Prostephanus truncatus) and the maize weevil (Sitophilus zeamais) are major pests of stored maize. Given the threat of these insects to our maize supply, the increasing insecticide resistance to currently used chemical control tactics such as phosphine, and the removal of effective chemistries from the market (methyl-bromide), there is a need for alternative integrated pest management tools. Here, we present a more realistic test of the effectiveness of a novel insecticide formulation (methoprene + deltamethrin + piperonyl butoxide, PBO; tradename, Gravista ®) in comparison to past conventional insecticide evaluations at reducing the horizontal dispersal capacity to food patches of both stored product species in comparison to an older formulation (methoprene + deltamethrin; tradename, Diacon IGR+®). For these experiments, we used a dispersal apparatus (consisting of 30 or 70 cm PVC pipe modified with a baited pitfall trap at one end) where we introduced cohorts of adults after exposure on concrete arenas at labeled rates and gave them 48 h to disperse to a novel food source consisting of 15 g of maize. The dispersal capacity for P. truncatus, measured as the percentage of adults dispersing to the novel food source, was significantly reduced by 90–97% after exposure to Gravista or Diacon IGR+ compared to the control. By contrast, the dispersal capacity for S. zeamais was only reduced by 5–25% after exposure to either insecticide formulation compared to the control. Both formulations performed equally well for each individual species, but dispersal of S. zeamais was not strongly impacted. Overall, our study highlights the importance of using realistic behavioral assays in comprehensive insecticide testing to provide a full picture of insecticide efficacy.

Sub-Lethal Effects of Pirimiphos-Methyl Are Expressed to Different Levels in Wings of Three Stored-Product Coleopterans: A Geometric Morphometrics Investigation

Tenebrio molitor L. (Coleoptera: Tenebrionidae), Prostephanus truncatus (Horn), and Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) are noxious insect pests of grains in storages. Pirimiphos-methyl is widely used to protect grains at the post-harvest stage. However, the sub-lethal impact of this active ingredient on the offspring of all three coleopterans remains unknown. Thus, mated females of each species were exposed separately to pirimiphos-methyl at short exposures (30 min, 3, 5, 8, 16, 24, and 36 h), where the elytra and hindwings of the adult progeny were analyzed with the geometric morphometrics method. Males and females of all species were incorporated into the analysis. The results revealed variability among species. Tenebrio molitor was the most sensitive among three species, displaying significant deformations in the elytra and hindwings. Males had more conspicuous morphological changes than females. Prostephanus truncatus hindwings exhibited deformities after 36 h of exposure to pirimiphos-methyl. In contrast, R. dominica offspring were not affected by pirimiphos-methyl. In light of our findings, organophosphorus insecticides may cause variable sub-lethal effects to stored-product insects. This issue may lead to different insecticidal treatments according to the targeted stored-product species.

The Effect of Temperature and Nutrient on Developmental Biology and Physiology of Stored-Product Species of Coleoptera

Insect pests of stored crops damage agricultural products in the fields or warehouses and cause crop loss. For this reason, it is of great importance to protect the products in warehouses after harvest. Many chemical control methods are being researched to prevent the damage they cause to the stored product. As the negative effects of these chemicals used in recent years on the environment and living things have been understood, different methods have been started to be developed. Because insects adapt to the environment very quickly, they develop more resistance to the chemicals used over time. For this reason, the biology and physiology of insects should be well known in the fight against insects. The better the biology and physiology of an insect are known, the more new methods can be developed in the integrated control methods of this insect. Insects are poikilothermic organisms. In other words, since they are organisms dependent on changes in environmental temperatures, temperature is very important in their development. Another factor affecting the biology and physiology of insects is nutrient. Temperature and food together can limit insect developmental stages. While high temperatures prolong the developmental stages, it can have the opposite effect in the adult period. Or insects feeding on poor quality nutrient can affect egg and adult size or cuticle development, as seen in some beetles. In this review study, the effects of temperature and nutrient on the biology and physiology of storage product pest Coleopters were evaluated.

Orientation of Tribolium castaneum (Coleoptera: Tenebrionidae) adults to 4,8-dimethyldecanal, kairomone and botanical oils following ambient, low, or high temperature exposure

The aggregation pheromone 4,8-dimethyldecanal (4,8 DMD) used alone or with kairomone-baited traps generally is used for monitoringTribolium castaneum (Herbst) but low efficiency is reported. Furthermore, insect orientation to pheromones and kairomones following low or high temperature exposure is not yet understood. This research evaluated the orientation of T. castaneum adults to 4,8 DMD and common kairomones following exposure to ambient, low or high temperatures. Fifty adults were introduced to the middle of rectangular glass chamber, and movement to the treatment or control was determined after 1 h. In experiment 1, insects reared at 30°C were used. Experiments 2 and 3 used insects exposed to 10°C for 4 days (cold temperature) and 42°C for 12 h (brief high temperature), respectively at 2–8 h following cold or heat exposure. The highest trapping occurred when 4,8DMD was combined with neem oil whereas the lowest was in coconut oil alone. Neem oil alone demonstrated repellent action. Prior exposure to cold or heat initially reduced taxis of T. castaneum adults to traps. The attraction for adults exposed to cold and heat was restored after 6–8 h when traps contained pheromone + neem or coconut oil. This study marks the first to experimentally test how exposure to high or low temperatures, two key IPM tactics in the post-harvest supply chain, affects the behavioral response of an important stored-product species to pheromone- and kairomones-baited traps.

Development of Necrobia rufipes (De Geer, 1775) (Coleoptera: Cleridae) under constant temperatures and its implication in forensic entomology

After the death of humans or animals, the odors released at different stages of decay attract various insects, and other arthropods, to the corpses. Therefore, the development of insects, and other arthropods present on corpses, can be assessed to estimate the minimum postmortem interval since death. In general, necrophagous blow flies are the insects that first colonize corpses. With progressing decay, other necrophagous and predatory insects arrive at the corpses, which will develop on or around these either by feeding directly on the corpses or by prey on other immature insects. Beetles (Coleoptera) mainly arrive at the corpses during the later stages of decay, and play important roles in cases with longer postmortem intervals. Necrobia rufipes (De Geer, 1755) (Coleoptera: Cleridae) is an important stored-product species with world-wide distribution. Moreover, it is also a forensically important insect species. At temperatures of 22, 25, 28, 31, 34, and 36°C (±0.5°C), the developmental periods from egg to adult were 113.20±2.96, 66.16±3.22, 50.61±1.95, 38.26±2.48, 37.97±2.40, and 31.20±2.11 days, respectively. In vivo measurements obtained the morphological indexes of larvae. The growth curve and the equation of the relationship between development time, body lengths, and mesonotum widths were simulated. The isomorphen diagram model, the isomegalen diagram model, and the thermal summation model were established. In addition, the widths of head capsules and pronota of larvae at different instars were determined by cluster analysis. Classifiers were created and validated by linear discriminant analysis.

Methyl Benzoate as a Putative Alternative, Environmentally Friendly Fumigant for the Control of Stored Product Insects.

Historically, stored product insect pest management has been based around the use of methyl bromide and phosphine as fumigants. However, methyl bromide has been phased out for structural fumigations, and there is increasing worldwide insecticide resistance to phosphine. One potential alternative, environmentally friendly option is the use of methyl benzoate (MBe), which is considered a food safe compound. In this study, we evaluated the direct and sublethal effects of MBe exposure on the survivorship and mobility of four stored product species with diverse life histories, including Rhyzopertha dominica, Tribolium castaneum, Sitophilus zeamais, and Trogoderma variabile. Sets of insects were exposed to a control, low, or high MBe concentrations in flasks with or without food for 24 or 72 h in the laboratory. Furthermore, we assessed phosphine exposure under similar conditions. Overall, R. dominica was the most susceptible to MBe exposure, followed by T. castaneum. By contrast, S. zeamais and T. variabile were relatively unaffected by MBe exposure. Exposure to MBe induced multiple-fold decreases in the total distance moved and velocity of adults still considered alive or affected after assays. By comparison, phosphine effectively killed all individuals of all species. Our data suggest that while MBe was effective for R. dominica, it was not competitive in comparison to phosphine for controlling susceptible strains of these species at the specified experimental conditions.

Biological activity of two new pyrrole derivatives against stored-product species: influence of temperature and relative humidity.

Members of the pyrrole group are likely to have interesting properties that merit additional investigation as insecticides at the post-harvest stages of agricultural commodities. In the present work, the insecticidal effect of two new pyrrole derivatives, ethyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3i) and isopropyl 3-(benzylthio)-4,6-dioxo-5-phenyl-2,4,5,6-tetrahydropyrrolo[3,4-c]pyrrole-carboxylate (3k) were studied as stored-wheat protectants against two major stored-product insect species, the confused flour beetle, Tribolium confusum Jaquelin du Val adults and larvae and the Mediterranean flour moth, Ephestia kuehniella Zeller larvae at different doses (0.1, 1 and 10 ppm), exposure intervals (7, 14 and 21 days), temperatures (20, 25 and 30°C) and relative humidity (55 and 75%) levels. For T. confusum adults, in the case of the pyrrole derivative 3i, mortality was low and it did not exceed 32.2% in wheat treated with 10 ppm 3i at 30°C and 55% relative humidity. Progeny production was very low (<1 individual/vial) in all combinations of 55% relative humidity, including control. In the case of the pyrrole derivative 3k, mortality reached 67.8% at 30°C and 55% relative humidity in wheat treated with 10 ppm after 21 days of exposure. Progeny production was low in all tested combinations (≤0.7 individuals/vial) of 55% relative humidity, including control. For T. confusum larvae, in the case of the pyrrole derivative 3i, at the highest dose, mortality was 82.2% at 25°C and 55% relative humidity whereas in the case of 3k it reached 77.8% at the same combination. In contrast, mortality at 75% relative humidity remained very low and did not exceed 13.3%. For E. kuehniella larvae, the highest mortalities, 44.4 and 63.3%, were observed in 10 ppm at 25°C and 55% relative humidity for both pyrrole derivatives. The compounds tested here have a certain insecticidal effect, but this effect is moderated by the exposure, the target species, the temperature and the relative humidity.

Effects of Rearing Density, Age, Sex, and Food Deprivation on Flight Initiation of the Red Flour Beetle (Coleoptera: Tenebrionidae)

Effects of rearing density, adult density and sex ratio in the flight chamber, adult age, sex, presence or absence of food, and duration of food deprivation on rate of and time to flight initiation of the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), were studied in the laboratory. Rates of flight initiation were slightly lower at lower rearing densities, but they did not differ with age or sex of adults, presence or absence of food in the flight chamber, or duration of food deprivation. Focal adults were less likely to fly when individuals of the opposite sex were present in flight chambers. Presence of the same sex or mixed sexes and numbers of individuals in flight chambers did not affect tendency to fly of focal individuals. Mean time to flight of older beetles (7-20 d old) was less than that of younger beetles (1-4 d old). No young beetles flew during the first 24 h of flight tests. Mean time to flight did not differ with rearing density, sex, presence or absence of food, or duration of food deprivation. Our results indicate that this species is highly dispersive during the adult stage and that flight does not seem to be associated with just prereproductive or postreproductive dispersal phases, high rearing density, or short to medium periods of food deprivation. Therefore, T. castaneum level of flight activity does not seem to be associated with factors that have been shown in the literature to increase dispersal by walking for this species and to increase flight initiation in other stored-product species.

Stored-product insects associated with a retail pet store chain in Kansas.

The types and numbers of insect species associated with eight Kansas retail stores belonging to a pet store chain were surveyed during February to August 2001. Insects were monitored at 1-3-wk intervals using food- and pheromone-baited pitfall traps for beetles and pheromone-baited sticky traps for moths. Thirty traps of each type were placed within a store. Thirty insect species belonging to 20 families in four orders were recorded from the eight stores. The weevils, Sitophilus spp.; Indianmeal moth, Plodia interpunctella (Hübner); and merchant grain beetle, Oryzaephilus mercator (Fauvel), were the most common and abundant species in all stores, whereas the red-legged ham beetle, Necrobia rufipes (Degeer), and red flour beetle, Tribolium castaneum (Herbst), were abundant only in one store. The numbers of each insect species captured varied from store to store. In each of the stores, a total of 12-19 stored-product species were captured in traps, and seven of the eight stores had relatively high species diversity. With the exception of one store, the different types of insect species found among the remaining seven stores were essentially similar. The mean density of insects in infested bulk-stored and bagged pet food products removed from a store ranged from 65 to 656 adults/kg. The types and numbers of insect species captured in traps indicated that infestations were well established in the surveyed stores. Early detection and management of these infestations is critical for maintaining quality and integrity of food products sold in the pet stores.

Upwind flight of Prostephanus truncatus is mediated by aggregation pheromone but not food volatiles

Flight bioassays were carried out to investigate the response of Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) to maize volatiles in comparison to the male-produced aggregation pheromone. Upwind attraction of flying P. truncatus is mediated by the male-produced aggregation pheromone. In contrast, beetles showed no response to maize grains or volatiles, and no interactions between aggregation pheromone and maize volatiles were recorded. This absence of upwind flight to food volatiles, or any synergism between pheromone and food volatiles suggests that the male-produced aggregation pheromone is the only known long-range semiochemical used by P. truncatus for dispersal and host-selection. These results are in contrast with those on several other stored-product species, and suggest that P. truncatus may not use maize volatiles as long-range host finding kairomones in nature. We propose a hypothesis for the process of dispersal and host colonisation by P. truncatus.

INFLUENCE OF GRANARY TYPE AND FARM PRACTICES ON THE RELATIVE ABUNDANCE OF INSECTS IN GRANARY RESIDUES

AbstractThe abundance of nine stored-product species found in crop residues in farm granaries in the Prairie Provinces was influenced by farm practices, kinds of crops stored in the granaries, and the materials used in the construction of the granaries.Some species were found more frequently than expected on farms where there had been previous infestations (Pyralis farinalis L.), or where there was livestock (Cryptolestes ferrugineus [Stephens]).Fewer samples than expected were found infested with Cryptophagus varus (W. &amp; C.), where insecticidal sprays were used, but more C. ferrugineus than expected were found where fumigants or insecticidal sprays were used.Fewer samples of canola residues than expected contained insects, but barley residues contained more insects than expected.Wooden granaries contained more insects than expected, except for C. ferrugineus.Cole’s coefficient of association showed that some species were often associated but other pairs of species such as Tribolium audax Halstead and Lathridius minutus L. were negatively associated.These relationships between species and their environments can be used to reduce the abundance of stored-products insects in farm granaries.

DISTRIBUTION OF INSECTS FOUND IN GRANARY RESIDUES IN THE CANADIAN PRAIRIES

AbstractA distribution study of stored-product and other insects in unswept, empty farm granaries was conducted in Manitoba in 1981, in Saskatchewan in 1982, and in Alberta in 1984.Thirteen species of stored-product insects were found in Manitoba and Saskatchewan and 12 in Alberta, indicating uniform geographical distribution among the number of pest species throughout the prairies. The most common was Tribolium audax Halstead, followed by Cryptolestes ferrugineus (Stephens) and Tenebrio molitor L. Nine fungus-feeding species were found in Manitoba, 12 in Saskatchewan, and 12 in Alberta. The most common fungus feeders were Lathridius minutus (L.), Corticarina cavicollis Mann., Cryptophagus varus W.&amp;C., and Corticaria serrata (Paykull). Five non-stored product species of insects that were scavengers, predators, or were sheltering in the granaries were found in Manitoba, 31 in Saskatchewan, and 10 in Alberta.The distribution of six stored-product species, two fungus-feeding species, and one scavenger did not show a uniform abundance in the three prairie provinces, either in their distribution on farms or in granaries.

A field demonstration of odour-based, host-food finding behaviour in several species of stored grain insects

In order to demonstrate odour-based, host-food finding behaviour in field populations of stored grain insects, traps were inserted into the fabric of PVC-covered, fully sealed, earth-walled storages at two sites in New South Wales, Australia. Cryptolestes ferrugineus, Rhyzopertha dominica and Tribolium castaneum were trapped relatively commonly, as were the economically less significant Carpophilus dimidiatus, Typhaea stercorea and Ahasverus advena. Trap odours from stored wheat contributed markedly to the attraction of all six species. Other species were taken also, mainly those associated with moist grain. These results are discussed in relation to the abundance of stored-product species in the trapping area.