Confusum Adults Research Articles

Insecticidal activity of two amorphous silica powders applied to concrete surfaces against the confused flour beetle, Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae)

The increased demand for residue-free food grains has led to exploring diatomaceous earth formulations as potential alternatives to synthetic insecticides. In the present study, we evaluated the efficacy of two amorphous silica powders 1 and 2 with different elemental composition, particle diameter, and shape characteristics against the confused flour beetle, Tribolium confusum Jacquelin du Val. The insecticidal activity of the two silica powders was determined by exposing T. confusum adults to silica powder treated concrete arenas at different application rates (0, 0.5, 0.75, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 g/m2) for 12, 24, 36, and 48 h. Mortality assessments were made after 14 d, and adult progeny counts were made at 42 d. Silica powder 2 demonstrated greater efficacy and produced 100% adult mortality and completely inhibited adult progeny production when adults were exposed for 24 h to an application rate of 4.0 g/m2. Complete mortality and complete suppression of adult progeny production was noticed after 36 h exposure to 3.5 g/m2 of silica powder 1. Exposure of T. confusum adults to 6 g/m2 of silica powder 1 and 4 g/m2 of silica powder 2 gave complete mortality after 24 and 20 h, respectively. No adult progeny production was observed when adults were exposed for 24 h to 6 g/m2 and 4 g/m2 of silica powder 1 and silica powder 2, respectively. These findings suggest that the two silica powders hold promise for managing T. confusum, particularly in treating empty bin floors before storing new grains.

Chemical Profiling, Insecticidal, and Phytotoxic Effect of Essential Oils from Leaves and Inflorescence of Moroccan Chenopodium ambrosioides (L.).

Chenopodium ambrosioides (L.) is a medicinal and aromatic plant widely used in the Moroccan traditional medicine for its important pharmacological properties. In order to contribute to the valorization of this plant, the current study aimed at evaluating, for the first time, the variation in the yield, chemical composition, and insecticidal and phytotoxic activities of C. ambrosioides essential oil (CAEO) isolated from leaves and inflorescences. The results obtained showed that the CAEO yields vary significantly according to the distilled plant part, with 0.75 ± 0.15% for the leaves and 1.2 ± 0.34% for the inflorescences. CAEO profiling showed quantitative more than qualitative differences. Leaf CAEO was rich in δ-3-carene (61.51%), followed by p-cymene (14.67%) and 1,2:3,4-diepoxy-p-menthane (6.19%). However, inflorescence CAEO was dominated by the same compounds but with variable levels (δ-3-Carene: 44.29%; 1,2:3,4-diepoxy-p-menthane: 19.46%; and p-cymene: 17.85%). The CAEOs from the leaves and inflorescences showed a very interesting inhibiting effect on the germination and growth of the three species used, namely Medicago sativa, Linum rusitatissimum, and Raphanus sativus. However, there was no significant difference between these CAEOs. Similarly, for the insecticidal activity, CAEOs exhibited an important and similar toxicity against Tribolium confusum adults with LD50 of 4.30 and 4.46 μL/L of air and LD90 of 6.51 and 9.62 μL/L air for toxicity by fumigation, while values for contact toxicity on filter paper were 0.04 and 0.05 μL/cm2 for LD50 and 0.08 and 0.09 μL/cm2 for LD90.

Fabrication of Carum copticum essential oil-loaded chitosan nanoparticles and evaluation its insecticidal activity for controlling Rhyzopertha dominica and Tribolium confusum.

Plant essential oils (EOs) can be used as a feasible tool for insect pest control. Nanoparticle formulations of plant EOs can improve the efficiency and stability of EOs, as well as insecticidal potential. In this study, Carum copticum L. essential oil-loaded nanoparticles (OLNs) were prepared via an oil-in-water emulsion, followed by droplet solidiffication via ionic gelation using a cross-linker, sodium tripolyphosphate (TPP). The nanoparticles were characterized by ultraviolet and visible (UV-Vis) spectrophotometry, Fourier-transform infrared spectroscopy (FTIR), laser light scattering (LS), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Moreover, the insecticidal activity of C. copticum EO and OLNs was evaluated against Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) and Tribolium confusum Jacquelin du Val. (Coleoptera: Tenebrionidae). In addition, their effectiveness was assessed on the progeny production of tested insect species. The loading efficiency ranged from 34.33 to 84.16% when the chitosan to EO weight ratio was 1:1.25 and 1:0.5, respectively. The loading efficiency decreased with increasing EO content in the nanoparticles. The OLN particles exhibited spherical shape. The particle size was in the range 120-223.6 nm and increased with the increase of EO to chitosan ratio. So that the largest mean particle size (223.6 nm) was reported in the 1:1.25 weight ratio of chitosan to the EO. The mortality percentage of R. dominica and T. confusum adults were 74 and 57% when exposed for 7 days to 2000 mg/kg of OLNs at the 1:1.25 weight ratio, while EO caused 62 and 44% mortality on both insect species, respectively. Therefore, OLNs can potentially improve the insecticidal activity of C. copticum EO and could be applied to facilitate control of stored-product insect pests.

Insecticidal properties of etofenprox for the control of Ephestia kuehniella, Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum on stored barley, maize, oats, rice, and wheat.

Etofenprox is a novel pyrethroid insecticide that targets the nervous system of insects by affecting the function of the sodium channel. The current study examines the insecticidal activity of etofenprox against Ephestia kuehniella (Lepidoptera: Pyralidae) larvae, Rhyzopertha dominica (Coleoptera: Bostrychidae) adults, Sitophilus oryzae (Coleoptera: Curculionidae) adults, and Tribolium confusum (Coleoptera: Tenebrionidae) adults and larvae on different grain commodities. For this purpose, etofenprox was applied on barley, maize, oats, rice, and wheat at 0.1, 1, 5, and 10ppm. Mortality levels were recorded after 7, 14, and 21days of exposure. For E. kuehniella larvae, 10ppm applied on whole rice killed 96.1% of the exposed individuals after 21days of exposure.The application of etofenprox on oats at 5ppm caused the death of 98.3% of the exposed R. dominica adults. Complete mortality was observed for R. dominica adults 21days post-exposure to oats and whole rice treated with 10ppm etofenprox. The highest concentration applied on barley caused 95.0% mortality to S. oryzae adults, while the same concentration on maize killed 76.8% of T. confusum adults after 21days of exposure. Larvae of T. confusum exhibited high mortality levels reaching 99.4% after 21days of exposure to barley treated with 10ppm etofenprox. Progeny production of parental R. dominica adults was almost suppressed on all commodities treated with 5ppm etofenprox. The offspring emergence of S. oryzae ranged between 4.4 and 24.6 adults per vial at 10ppm. No T. confusum progeny was produced at 10ppm etofenprox. Our results document that etofenprox is highly effective as grain protectant against several insect species, their developmental stages and their progeny production, but its performance depends on the type of the commodity that it is applied on.

A Preliminary Analysis on the Insecticidal Effect of Cyantraniliprole against Stored-Product Pests

While existing insecticides are becoming obsolete, the need for research and application of alternative substances is growing. Cyantraniliprole is a second-generation ryanodine receptor with the ability to bind and activate the ryanodine receptors in insect striated muscle cells, causing continuous muscular contraction, paralysis, and death. Many studies indicate its effectiveness on a variety of insects, but its action on storage pests has not yet been reported. We successfully conducted experiments for the first time on adult Tenebrio molitor, Tribolium confusum, Alphitobius diaperinus, Rhyzopertha dominica, and Trogoderma granarium with application of cyantraniliprole, causing dose-dependent mortality. Bioassays were carried out in the laboratory, where experimental adults were sprayed with six concentrations of cyantraniliprole. Mortality was recorded at 7, 14, 21, and 28 days after exposure. Mean mortality, survival concentration, and survival time were estimated for each species. The concentrations with both the highest mortality and the lowest survival rate were 2500 and 3000 ppm. Our results indicate that the tested insecticide was effective against T. confusum adults and is a promising pesticide for use in storage facilities.

Etofenprox as grain protectant for the management of five key stored-product insect pests.

Etofenprox is a broad spectrum pyrethroid insecticide with low toxicity to mammals, fishes, and honeybees. In the present study it was evaluated as grain protectant against Ephestia kuehniella (Lepidoptera: Pyralidae) larvae,Prostephanus truncatus (Coleoptera: Bostrychidae) adults,Rhyzopertha dominica (Coleoptera: Bostrychidae) adults, Sitophilus oryzae(Coleoptera: Curculionidae) adults, and Tribolium confusum (Coleoptera: Tenebrionidae) larvae and adults. Etofenprox was applied at 0.1, 1, 5, and 10 ppm on wheat, or maize in the case of P. truncatus, and tested at different combinations of temperatures (20, 25, and 30 °C) and relative humidity (RH) levels (55 and 75%). Progeny production of the tested coleopteran adult species was also assessed. For E. kuehniella, after 21 days of exposure 75.6% of the exposed larvae were killed at 20 and 30 °C/55% RH. Mortality of P. truncatus adults reached 99.4 and 97.8% at 10 ppm of 55 and 75% RH, respectively, at 30 °C. For S. oryzae, after 21 days of exposure, mortality was moderate at both RH levels, even at the elevate doses, reaching 66.7% at 10 ppm at 20°C/75% RH. All R. dominica adults died 21 days post-exposure at 30°C/55% RH and 25 or 30°C/75% RH at 10 ppm. For T. confusum adults, mortality was 81.1% 10 ppm 21 days post-exposure at 20°C/75% RH. Etofenprox killed 99.4% of the exposed T. confusum larvae at 10 ppm respectively 14 days post-exposure at 25°C/55% RH. Concerning progeny production, complete suppression was recorded for P. truncatus, R. dominica, and T. confusum in various combinations of temperature/RH. Our findings indicate that etofenprox is a well-promising insecticide for the protection of stored grains. However, its performance differs among insect species and abiotic conditions.

Identification of chemosensory genes by antennal transcriptome analysis and expression profiles of odorant-binding proteins in parasitoid wasp Aulacocentrum confusum

The endoparasitoid wasp, Aulacocentrum confusum (Hymenoptera: Braconidae), is a preponderant natural enemy of the larvae of Glyphodes pyloalis Walker (Lepidoptera: Pyralidae), which is a destructive pest of mulberry trees. We first constructed the antennal transcriptome database of A. confusum. In total, we obtained 48,262,304 clean reads from the dataset and assembled 24,324 unigenes. A total of 12,690 (52.17%) unigenes indicated significant similarity (E-value < 10−5) compared to known protein sequences of other species from the NCBI non-redundant protein database. Gene ontology (GO) and cluster of orthologous groups (COG) analyses were used to determine the functional categories of these genes. A total of 84 putative chemosensory genes were identified from the antennal transcriptome of A. confusum, including 11 putative odorant-binding protein (OBP) genes, six chemosensory protein (CSP) genes, 44 olfactory receptor (OR) genes (including one olfactory co-receptor, Orco), 19 ionotropic receptor (IR) genes, and four sensory neuron membrane protein (SNMP) genes. Results of qPCR assays indicated that among of 11 AconOBPs, nine AconOBP genes were significantly expressed in the antennae of A. confusum adults. AconOBP8 was significantly expressed in the abdomen and AconOBP10 was highly expressed in the thorax. These findings can build a basis for further study on the processes of chemosensory perception in A. confusum at the molecular level.

Bioactive Substances of Cydonia oblonga Fruit : Insecticidal Effect of Tannins on Tribuliumm confusum

ABSTRACT The objective of this study was to evaluate the phytochemical, antimicrobial, and insecticidal properties of tannins derived from Cydonia oblonga fruit. Qualitative and quantitative methods were used for the determination of the phytochemicals of Cydonia oblonga fruits. The tannins of this fruit were extracted using solvents and salts, and their antimicrobial activity against S. aureus ATCC 25923 and E.coli ATCC 25322 and C.albicans was investigated. The lethal effect of tannins extract was evaluated on Tribolium confusum under controlled laboratory conditions (at temperature 28 ± 2°C, relative humidity 75 ± 5%, and photoperiod of 16:8). The obtained results showed very interesting levels of tannins extraction (9.66%, 7.33%) using solvents and salts, respectively. The obtained tannins exerted no antimicrobial activity for the tested strains. On the other hand, all doses (50 μl, 100 μl, and 200 μl) of tannins tested on Tribolium confusum adults by the inhalation method showed a bio-insecticidal effect with an LD50 of 109.64 μl of tannin extract. Cydonia oblonga fruit can be an alternative for the development of natural drugs and insecticides with an important role in the fight against parasites.

Insecticidal effects of some essential oils against Tribolium confusum (du Val.) and Acanthoscelides obtectus (Say), (Coleoptera: Tenebrionidae and Bruchidae) adults

In this study, insecticidal effects of the essential oils obtained from plants Ocimum basilicum L., Rosmarinus officinalis L. and Artemisia dracunculus L. on confused flour beetle (Tribolium confusum du Val., 1863 (Coleoptera: Tenebrionidae)) and bean weevil (Acanthoscelides obtectus (Say), 1831 (Coleoptera: Bruchidae)) adults were tested in laboratory conditions. In this context, T. confusum and A. obtectus adults were exposed to essential oils at 10 and 20 μL/petri doses for 24, 48, 72 and 96 h. All of the essential oils used in the study caused mortalities at different rates in two application doses but end of the 96 h all mortality rates were obtained similar (O. basilicum 98.3%, R. officinalis 98.3%, A. dracunculus 93.3% against T. confusum adults; O. basilicum 100%, R. officinalis 100%, A. dracunculus 100% against A. obtectus adults). It was determined that the effects of essential oils on A. obtectus adults were greater than T. confusum adults. Especially when the dosage was 20 μL, the death rate increased up to over 95% after 96 h for all types. The mortality rates increased with increasing exposure period at the 48, 72 and 96 h. in all applications. The results of the study suggest that essential oils from O.basilicum and R.officinalis could have a potential as control agents against A. obtectus and T.confusum adults under storage conditions.

Effects of terpinen‐4‐ol fumigation on protein levels of detoxification enzymes in Tribolium confusum

Terpinen-4-ol has high fumigating activity to stored-grain pests including Tribolium confusum. To understand the detoxification of terpinen-4-ol in insects, proteomic analysis was performed to identify related proteins and pathways in response to terpinen-4-ol fumigation in T. confusum. By using isobaric tags for relative and absolute quantitation (iTRAQ)-based strategy, 4,618 proteins were obtained from T. confusum adults in the present study. Comparative proteomic analysis showed that 148 proteins were upregulated and 137 proteins were downregulated in beetles under the LC50 of terpinen-4-ol treatment for 24 hr. According to functional classifications, differentially expressed proteins (DEPs) were enriched in xenobioticmetabolism pathways. In the detoxification pathway, the levels of 25 cytochrome P450s, 5 glutathione S-transferases, and 2 uridine diphosphate (UDP)-glucuronosyltransferases were changed, most of which were upregulated in T. confusum exposed to terpinen-4-ol. The results indicated that terpinen-4-ol was potentially metabolized and detoxified by enzymes like P450s in T. confusum.

Biochemical Comparative Study between Irradiated Adult Tribolium confusum and Adults Feed on Irradiated Flour

Nowadays, radiation technique is widely used food preservation and pest control. Therefore, the present study was conducted to investigate the biochemical alterations in Tribolium confusum adults irradiated with the sterilizing dose (60 Gy) or fed on flour irradiated with the sterilizing dose for flour (3Kg). The results indicated a significant decrease in the nutritional contents (protein, lipids, and carbohydrates) in the studied samples when compared to control. The digestive enzymes (protease, lipase, and amylase) of T. confusum adults were estimated and they revealed that protease and amylase activities showed a significant decline in the gamma-irradiated adults, and a significant elevation in adults feed on irradiated flour. Moreover, lipase activity was non-significantly changed in the studied samples when compared to the control. In conclusion, it is noticeable that gamma irradiation of T. confusum more effective than flour irradiation but we can use food irradiation technique in combination with other control tools for controlling T. confusum.

Laboratory evaluation of Turkish diatomaceous earths as potential stored grain protectants

In this study, efficacy of local diatomaceous earths (DE) collected from different regions of Turkey against stored grain insects, Sitophilus oryzae (L.), Tribolium confusum du Val. and Rhyzopertha dominica (F.), was investigated. For this purpose, biological tests were carried out at concentrations of 500 and 1000 ppm (mg DE / kg wheat) of 9 local diatomaceous earths and one commercial diatomaceous earth, namely Silicosec® as positive control at 25 ± 1 ° C temperature and 65 ± 5% relative humidity in wheat. In addition, the studies on some of the chemical and physical analysis of the tested diatomaceous earths (silicon dioxide (SiO2) ratio, particle size and adhesion rate on commodity) were also conducted. In biological tests conducted at 500 ppm concentration for 14 days of exposure in wheat the highest mortality rates (97 to 98%) of S. oryzae adults were recorded in CB2N-1, AGN-1 and BGN-1 diatomaceous earths, while the highest mortality rates of T. confusum adults were obtained from only AGN-1 and BGN-1 diatomaceous earths. In the case of R. dominica, the highest mortality rate (64.4%) was recorded only in CB2N-1 diatomaceous earth. At concentration of 1000 ppm for 14 days of exposure in wheat, 100% mortality of S. oryzae adults was observed in all tested local diatomaceous earths except FB2N-1 and Silicosec® while mortality rates of T. confusum adults ranging from % 95 to %100 were obtained in all tested local diatomaceous earths except FB2N-1, FBN-1 and Silicosec®. In the case of R. dominica adults, mortality rates ranging from 80% to 93% were recorded in CB2N-1, CCN-1 and AG2N-1 diatomaceous earths. In conclusion, laboratory bioassays indicated that CB2N-1 and BGN-1 local diatomaceous earths had high efficacy against S. oryzae, T. confusum and R. dominica adults and thus could be potential to be successfully used for controlling stored grain insect pests as a grain protectant.

Insecticidal efficacy of silica nanoparticles against Rhyzopertha dominica F. and Tribolium confusum Jacquelin du Val

Abstract Bioassays were conducted to assess the effects of two silicon dioxide nanoparticles of Aerosil® and Nanosav against adults of Rhyzopertha dominica F. and Tribolium confusum Jacquelin du Val. Silica nanoparticles were applied at the rates of 50, 100, 200 and 300 mg · kg−1 on wheat and peeled barley. The mortality was counted after 1, 2, 3, and 7 days of exposure. Another experiment was carried out to evaluate the effect of food source on the survival of beetles after exposure to silica nanoparticles. Adults were exposed to silica nanoparticles at the rate of 0.2 mg · cm−2 for 1 and 2 days on filter paper inside plastic Petri dishes, respectively. After exposure, the initial mortality was counted and live individuals of both species were held for a week in empty glass vials or vials containing wheat and wheat flour, respectively. Silica nanoparticles have high toxicity on R. dominica and T. confusum adults. Rhyzopertha dominica was more susceptible than T. confusum. However, the mortality of both species increased with increasing concentrations and time exposed to each concentration. At low concentrations, Aerosil® was more effective than Nanosav. Silica nanoparticles were more effective in wheat grains than barley. Results indicated that the initial mortality was so high that the impact of food source on delay mortality was unclear in most cases. Silica nanoparticles were efficient against tested species and can be used effectively in a stored grain integrated pest management program.

Insecticidal effect of two novel pyrrole derivatives against two major stored product insect species

Several pyrrole compounds exhibit insecticidal properties against a wide range of insect pest species. In the present work, the insecticidal effect of the 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-grain protectants (maize and barley) against two major stored-product insect species, the confused flour beetle, Tribolium confusum Jaquelin du Val (Coleoptera: Tenebrionidae) adults and larvae and the Mediterranean flour moth, Ephestia kuehniella Zeller (Lepidoptera: Pyralidae) larvae at three doses (0.1, 1 and 10 ppm) and five exposure intervals (1, 2, 7, 14 and 21d). All T. confusum adults were dead at all doses on barley treated with 3i after 21d of exposure, while for 3k mortality was >92%. Progeny production was very low (≤1 individual per vial) at all doses for both pyrrole derivatives. Mortality of T. confusum larvae was not complete with any dose of both pyrrole derivatives but it exceeded 96% with 3k at 10 ppm after 21d of exposure on maize. For barley, all exposed larvae were found dead at all doses of both pyrrole derivates after 7d of exposure. Mortality of E. kuehniella larvae was complete at 1 and 10 ppm of 3i and all doses of 3k at 7d of exposure. After 14d of exposure, all E. kuehniella larvae were dead at 0.1 ppm of 3i. The results of the present study indicate that the tested compounds have elevated insecticidal effect against both species tested on certain combinations of dose, exposure interval and type of commodity.

Effects of electric infrared heating with light source penetration on microbial and entomological loads of dried currants and their organoleptic characteristics

A series of field bioassays was conducted to evaluate the effects of electric infrared (IR) penetration on microbial disinfection and insect control as well as on the organoleptic characteristics of dried black currants (Corinthian currants, Vitis vinifera L. var. Apyrena). A continuous IR processor was placed in the production line of an industrial facility and was used for the field assays. In a series of bioassays, currants were fed into the IR processor and examined with and without process agitation at different treatment parameters including retention times (ranging from 30 to 35 s) and various peak temperatures (45, 50, 55, 60, 65, 70 and 75 °C). Samples of processed currants were randomly selected for microbial analysis, as well as for determination of organoleptic characteristics. Infrared treatment resulted in a significant reduction of total viable counts, yeasts and moulds by factors ranging from 10 to 300. Increase of treatment time and peak temperature was positively correlated with microbial reduction. Sensory attributes were not affected up to 60 °C, while crystalline texture and overall acceptance were affected by IR treatment at 70 °C. With respect to currant phenolics, antioxidants that have potential benefits to human health, IR heating resulted in almost the same effect up to 65 °C, i.e. approximately 20 % reduction; higher peak temperatures further lowered total phenolic values. 5-hydroxymethylfurfural (HMF) formation was low up to 55 °C, while increased at higher temperatures; however, values still remained low as compared with dried fruit HMF levels. In another series of bioassays, golden sultanas were artificially infested with larvae of Ephestia elutella and adults of Oryzaephilus surinamensis and Tribolium confusum and treated with IR in agitating flow process at different peak temperatures (45, 50, 55, 60, 65 and 70 °C). Finally, a batch series of non-agitated flow process tests were conducted in glass Petri dishes. Briefly, O. surinamensis and T. confusum adults were exposed to IR penetration for different time exposure intervals (1, 2, 3, 4, 5, 8, 10 and 20 s) with and without the presence of currants and sultanas. In the bioassays with infested sultanas, all IR treatments with agitation provided complete control of the insect species tested, since IR-treated sultanas were found free of insects even 1 year after treatment. For exposure intervals higher than 4 s in the non-agitated flow process, all adults of O. surinamensis and T. confusum were killed in glass Petri dishes consisting of insects only and without the presence of currants and sultanas. In contrast, the presence of currants and sultanas in the non-agitated flow process reduced significantly the killing rate efficacy of IR against the insect species tested, especially on the individuals located beneath the sultanas and currants and where the infrared light could not penetrate them. Our results suggest that electric infrared heating with light source penetration could be a valuable tool for rapid and successful reduction of the microbial load and post-harvest insect disinfestation of dry currants and sultanas, provided that adequate agitation within the infrared process chamber is achieved so that sultanas and currants could be penetrated consistently in a three-dimensional manner.

Evaluation of spinetoram and spinosad for control of Prostephanus truncatus, Rhyzopertha dominica, Sitophilus oryzae, and Tribolium confusum on stored grains under laboratory tests

Spinetoram and spinosad have been evaluated against certain stored-product insect pests with success but there are no data available on the comparison of the efficacy of these two novel compounds in stored grains. Thus, laboratory bioassays were conducted to compare spinetoram and spinosad as grain protectants against Prostephanus truncatus (Horn) (Coleoptera: Bostrychidae) adults, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) adults and larvae. Factors such as treatment (1 ppm spinetoram, 1 ppm spinosad, 0.1 ppm spinetoram + 0.9 ppm spinosad, 0.5 ppm spinetoram + 0.5 ppm spinosad, and 0.9 ppm spinetoram + 0.1 ppm spinosad), exposure interval (1, 2, 7, and 14 days), temperature (20, 25, and 30 °C), and commodity (barley, maize, rye, and wheat) were evaluated. Progeny production was assessed after 60 days of exposure. Concerning temperatures, for P. truncatus adults, after 14 days of exposure, all adults were dead in treatments except of the case of spinosad alone at 20 °C. Offspring emergence was completely suppressed in all treatments at 20 and 25 °C. For R. dominica adults, after 7 days of exposure, the overall mortality ranged from 92.8 to 100 %. After 14 days of exposure, all adults were dead in all treatments of the combined use of spinetoram and spinosad at 25 and 30 °C. Progeny production was completely suppressed in all treatments at 30 °C. For S. oryzae adults, after 7 days of exposure, all S. oryzae were died at 25 and 30 °C in all treatments except in the case of spinosad alone. Offspring emergence was very low in all treatments and temperatures except in the case of spinosad alone at 30 °C. For T. confusum adults, after 1, 2, and 7 days of exposure, the overall mortality was low in all treatments and temperatures. Concerning commodities, for R. dominica adults, after 7 and 14 days of exposure, the overall mortality was >97 %. Offspring emergence was very low in all commodities. For S. oryzae adults, after 7 and 14 days of exposure, the overall mortality was increased exceeding 91 % except in the case of spinosad alone 7 days after exposure in barley. Progeny production was high in barley and rye in all treatments. For T. confusum adults, after 7 and 14 days, the overall mortality was low in barley, rye, and wheat. No offspring emergence was recorded in all treatments and commodities. For T. confusum larvae, after 14 days of exposure mortality was further increased, but did not reach 100 % for any of the combinations tested. The results of the present study suggest that the simultaneous application of spinetoram and spinosad was generally equally effective with the use of either spinosad or spinetoram alone. Furthermore, the increase of dose of either compound resulted in the same mortality levels. Thus, no benefits were achieved when spinetoram and spinosad were used simultaneously on grains, regardless of the proportion of each ingredient. These issues should be seriously considered when control measures against stored-product insects are designed.

Susceptibility of different life stages of Tribolium confusum to pyrethrin aerosol: effects of a flour food source on insecticidal efficacy

Accumulated grain dust and flour residues in flour mills can potentially decrease the efficacy of contact surface treatments and aerosol insecticides used for control of adult and immature stages of stored product insects. A study was conducted to evaluate the effects of flour residues on the efficacy of piperonyl butoxide-synergized pyrethrin aerosol against different life stages of the confused flour beetle, Tribolium confusum Jacquelin du Val. Twenty individual adults, pupae, or larvae of T. confusum, confined in Petri dishes containing 0, 0.1, 1, 5, or 10 g of wheat flour, were exposed separately inside an empty shed to the label rate of the aerosol. The formulation contained 1 % active ingredient pyrethrin and the label application rate was 1.04 ml/m3. After 2 h of exposure, all dishes were removed from the shed and placed in an incubator set at 27 °C and 60 % RH. Mortality of T. confusum adults decreased with increasing amount of flour. Recovery of moribund adults 15 days after exposure was greater in the 5 and 10 g flour dishes (15 and 46 %) compared to the 0.1 or 1 g flour dishes (0.7 and 5 %). As the flour amounts increased, more larvae and pupae were able to emerge as adults. Results show accumulated flour residues during aerosol application can compromise aerosol efficacy, and also suggest the flour impaired penetration ability of the aerosol. These results also emphasize the importance of sanitation and cleaning to remove spillage and extraneous material prior to an aerosol application.

The toxicity effects of atmospheres with high content of carbon dioxide with addition of sulphur dioxide on two stored-product pest species: Sitophilus oryzae and Tribolium confusum

Modified atmospheres (MAs) are safe and environmentally friendly alternatives to control pests in stored products. However, to accommodate the requirements of the food industry, the control of insects by a MA can be a too lengthy process. This paper describes the potential of sulphur dioxide as an additive to reduce the long lethal exposure of modified atmospheres (MA) enriched with carbon dioxide for major stored product pests. Specifically, we evaluated whether the addition of SO2 (0–30,000 ppm) to a high-CO2 content of 70%–95% MA could enhance its insecticidal effect for the control of Sitophilus oryzae and Tribolium confusum. The addition of 15,000 ppm and 30,000 ppm of SO2 to 95% CO2 enhanced control up to 100% in comparison to CO2 alone for S. oryzae and T. confusum adults when treated for one day in all of the substrates tested. However, the effectiveness of adding SO2 at reduced contents was lower and depended on the substrate and pest species considered. The addition of SO2 also increased the mortality of all of the developmental stages of S. oryzae. The increase in mortality with the addition of SO2 was also observed when included with 70% CO2. Therefore, the addition of SO2 can be considered a feasible means of shortening the length of treatment necessary to achieve the control of these two pests using a high-CO2 MA.

Insecticidal effect of chlorantraniliprole against major stored-product insect pests in different grain commodities under laboratory tests

Chlorantraniliprole belongs to the chemical group of anthranilic diamides. It has selectivity to beneficial arthropods and low mammalian toxicity. Laboratory bioassays were conducted to assess chlorantraniliprole as a potential grain protectant against Ephestia kuehniella Zeller larvae, Liposcelis bostrychophila Badonnel adults, Rhyzopertha dominica (F.) adults, Sitophilus oryzae (L.) adults and Tribolium confusum Jacquelin du Val adults and larvae. Factors such as dose (0.01, 0.1, 1 and 10 mg chlorantraniliprole kg(-1) grain), exposure interval (7 and 14 days), formulation (chlorantraniliprole WG and chlorantraniliprole SC) and commodity (barley, maize, oats, peeled rice, whole rice and wheat) were evaluated for their impact on the insecticidal activity of chlorantraniliprole. Progeny production was assessed after 45 days of exposure in the case of L. bostrychophila adults and after 60 days of exposure in the case of R. dominica, S. oryzae and T. confusum adults. For L. bostrychophila adults, after 7 days of exposure, mortality was lower in maize and whole rice in comparison with the other commodities. Increase in dose generally increased mortality. Similar trends were also noted after 14 days of exposure. Offspring emergence was higher in maize and whole rice in comparison with the other commodities. For E. kuehniella larvae, after 7 days of exposure, significant differences were noted among the tested commodities. Increase in dose only slightly increased mortality in all commodities. After 14 days of exposure, mortality was further increased, but did not reach 100%. For R. dominica adults, after 7 days of exposure, increase in dose increased mortality significantly. After 14 days of exposure, mortality in barley, maize, whole rice and wheat exceeded 92% at 10 mg chlorantraniliprole kg(-1) grain. Offspring emergence was reduced, but 100% progeny suppression was not achieved. For S. oryzae adults, after 7 days of exposure, mortality was generally low at dose rates of ≤1 mg chlorantraniliprole kg(-1) grain. After 14 days of exposure, 100% mortality was noted in whole rice. For T. confusum adults, after 7 days of exposure, mortality was low. After 14 days of exposure, mortality increased proportionately for all commodities. Most progeny production was noted in oats. For T. confusum larvae, after 7 days of exposure, mortality was generally higher in comparison with adults. After 14 days of exposure, mortality in maize was high. Generally, the two formulations performed alike for all the insects tested. Based on the results of the present work, chlorantraniliprole is effective against major stored-product insect species. However, efficacy depends upon the type of commodity, the dose rate and the exposure interval.

Repellency of Ethanolic Extract of Some Indigenous Plants Against Tribolium confusum (du val))(Coleoptera: Tenebrionidae)

Repellency of ethanolic extracts of five plants extract viz. Eucalyptus gluaca, Melia azedarach, Mentha arvensis, Olea europaea leaves and pericarp of Punica granatum was tested against adult and larvae of the confused flour beetle Tribolium confusum using a choice test with treated filter paper. The plant extracts were applied at four concentrations which (2.5%, 5%, 7.5% and 10%) for each adult and larvae. All the plant extracts were found to be effective repellents and showed more than 20 % average repellency. The M.arvensis extract had potent repellent activity against T. confusum adults with 100 % repellency values with 2.5% concentration at 1h of exposure time for adult stage, while for larval stage it was observed that E. glauaca induce 100% repellency with concentration 7.5% at 2h after exposure. These naturally occurring plant extracts could be useful to protect the grains from the damages caused by of T.confusum. Keywords: Repellency, Tribolium confusum, plants extract, Indigenous Plants.