Adults Of Rhyzopertha Dominica Research Articles

Insecticidal, physiological, and biochemical effects of Schinus molle essential oil on the adults of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae)

Rhyzopertha dominica (F.) is considered as a major stored product pest. Conventional insecticides induce adverse effects on the environment. Plant derivative products constitute a promising alternative for pest control. The purpose of our research was to identify the chemical profile of essential oil (EO) extracted from Schinus molle L. (Anacardiaceae) and to evaluate the fumigant and the contact toxicity, and the repellent activity of this oil on adults of Rhyzopertha dominica F. (Coleoptera), a major pest in products that are stored around the world. The effects of this oil were examined on biochemical profile (energy reserves and Proteins), selective biomarkers like acetylcholinesterase (AChE), glutathione S-transferases (GST) and glutathione (GSH), and nucleic acids (DNA and RNA). Digestive enzymes were also investigated. The major chemical compounds identified by the GC-MS were α-phellandrene (16.613%), ß-phellandrene (12.104%), elemol (9.028%) and β-eudesmol (5.872%). Then, we evaluated the repellent activity, and also the effects in nutritional reserves and some biomarkers. This EO exhibited an insecticidal and repellent activity as a function of the exposure time and concentrations. Contact (LC50 at 24 h: 19.99 μL/mL) is the most effective mode of application compared to fumigation (LC50 at 24h: 174.30 μL/L air). S. molle EO was also investigated in digestive enzymes’ activities (α-amylase, lipase, chitinase and protease). Our results revealed a decrease in both α-amylase, lipase, protease and chitinase activities in treated adults compared to controls. In addition, we noticed a neurotoxic activity of S. molle EO traduced by a decrease of AChE. An induction of the detoxification system was observed via a decrease in GSH rate and an increase in GST activity. Moreover, the treatment induces an alteration of biochemical profile of R. dominica adults. Lastly, essential oil was examined on nucleic acids. Results showed an increase in DNA and RNA amount in treated adults when compared with control. Due to their effective source of bioactive compounds, the EO from the studied plant could be used as an alternative strategy for the management of stored product pests.

Insecticidal activity of crude olive pomace oils from Kabylia (Algeria) against the infestation of Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) in stored wheat grains

The insecticidal effect of four crude olive pomace oils extracted from pomace collected from four localities of Kabylia, refined olive pomace oil and extra virgin olive oil were assessed under laboratory conditions for the control of adults of Rhyzopertha dominica (Fabricius, 1792) (Coleoptera: Bostrychidae)) and Sitophilus oryzae (Linnaeus, 1763) (Coleoptera: Curculionidae). The doses used ranged from 0.1 to 0.4 ml/25 g of durum and soft wheat seeds. In addition, the quality indices and the fatty acid composition of these oils were evaluated. The results show that the legal quality indices were well within the legal limits for crude olive-pomace oil (COP), refined pomace oil (ROP) and extra-virgin olive oil (EVO) categories. The effectiveness of these vegetable oils is highly dependent on the insect species, the dose rate, the exposure time and the type of oil tested The main fatty acids from all samples tested, were oleic (61.89–79.25%), palmitic (8.34–15.71%) and linoleic (8.17–16.52%) acids. For both species and substrates tested, mortality is dose and time of exposure dependent. The highest dose (0.4 ml/25 g) causes ≥ 63.75% mortality, after 24 h of exposure. Comparison of LD50 (ml/25 g) indicates that olive oil was generally more toxic than crude and refined pomace oils, for both insects and substrates, values varies from 0.005 to 0.189. The most sensitive insect was S. oryzae for most vegetable oils tested. Likewise, oils significantly reduced the F1 offspring of both insects and seed weight losses. No progeny were observed in the two pests at the highest dose, and therefore no weight loss was recorded. The results also revealed that the six oils affect the germination capacity of durum and soft wheat seeds when the dosage is increased. The results collected remain encouraging for the recommendation of natural substances as part of integrated pest management programmes against insect pests of stored grains.

Formulation of pectin-Citrus aurantium essential oil-based packaging film and assessment of insecticidal performances against Rhyzopertha dominica on stored wheat

In stored wheat products, Rhyzopertha dominica (F) (Coleoptera: Bostrichidae) is an important pest that results in significant economic losses. Insect physiology and behavior can be affected by bioactive compounds extracted from plant wastes, which are important tools for developing bioincesticides. The purpose of this study is to develop an insecticidal packaging film based on pectin and essential oil (EO) extracted from Citrus aurantium (L., 1753) fruit peels.The encapsulation efficiency (EE) and cumulative release (CR) of C. aurantium EO into pectin film were determined. Further, Film packaging was tested against Rhyzopertha dominica adults reared on Karim and Khiar durum wheat (Tritichum durum Desf.) varieties. The fumigant toxicity was assessed after 10, 20, 30 and 40 days of storage. Moreover, emergence inhibition of R. dominica adults was determined. In addition, germination rate, weight loss and grain damage were examined.Results revealed that the lethal concentration that killed 50 % of the exposed adults developed into karim and khiar varieties were 278.45 and 688.79 µL/L air, respectively. Moreover, high encapsulation efficiency of C. aurantium essential oil into pectin film with an EE = 80.6 %. Moreover, pectin: EO film achieved complete (100 %) mortality and emergence inhibition of R. dominica adults for all storage periods. Also, pectin: EO film represent the better treatment which preserve the quality and quantity of wheat grains as well as grain damage, weight loss and germination rate. To concludepectin- C. aurantium EO film showed a significant fumigant effect against R. dominica adults and the emergence of their descendants after different storage periods and could be recommended as an active ingredient for a natural packaging against stored product insects.

Insecticidal activity of Iranian diatomaceous earth, alone or in combination with Mentha longifolia plant extract to control Rhyzopertha dominica adults on different cereals

Insecticidal activity of Iranian diatomaceous earth, alone or in combination with Mentha longifolia plant extract to control Rhyzopertha dominica adults on different cereals

Treatment of Four Stored-Grain Pests with Thiamethoxam plus Chlorantraniliprole: Enhanced Impact on Different Types of Grain Commodities and Surfaces.

An insecticide containing the neonicotinoid thiamethoxam + the diamide chlorantraniliprole was evaluated against adults of Rhyzopertha dominica, Tribolium castaneum, Trogoderma granarium, and Sitophilus oryzae under laboratory bioassays both on freshly treated grain as well as on treated grain stored over 90 days for its persistence in efficacy. In laboratory bioassays, the insecticide was applied on wheat, maize, or rice at four doses, while in persistence bioassays on wheat at the same doses. Mortality and progeny were assessed in both laboratory and persistence bioassays. After 14 days of exposure, S. oryzae exhibited 100% mortality on all three commodities at the highest dose, while R. dominica showed complete mortality on wheat or rice and T. castaneum on wheat. For a period of 90 days, S. oryzae exhibited 42.69% mortality, followed by R. dominica (35.26%), T. castaneum (27.08%), and T. granarium (18.63%) at the highest dose. Progeny was successfully suppressed in all cases of complete mortality in laboratory bioassays and for S. oryzae for 90 days in persistence bioassays. Laboratory trials were also performed on plywood, concrete, ceramic tile, and steel at one dose. The highest mortality was observed on steel, followed by concrete, ceramic tile, and plywood for all insect species tested. This study demonstrates that thiamethoxam + chlorantraniliprole is effective against the tested species depending on exposure, storage period, surface, commodity, and dose.

Comparative kinetic characterization of the activity of glycosylated and non-glycosylated trypsin-like serine protease isolated from adults of Rhyzopertha dominica (Coleoptera: Bostrichidae) reared on the grain of three different cultivars of wheat

Comparative kinetic characterization of the activity of glycosylated and non-glycosylated trypsin-like serine protease isolated from adults of Rhyzopertha dominica (Coleoptera: Bostrichidae) reared on the grain of three different cultivars of wheat

Comparative morphology of sensilla of antennae, maxillary and labial palpi of adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), with specific reference to the typology and possible functions

BackgroundThe lesser grain borer Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) is a cosmopolitan insect pest of stored cereal grains. In this study, the fine morphology of antennae, maxillary and labial palpi as well as the typology, morphology and distribution of associated sensilla were comprehensively examined by scanning electron microscopy.ResultsOn antennae, six types of sensilla were identified, s. trichodea, s. chaetica, two subtypes of s. basiconica, s. ampullacea and s. styloconica, in addition of Böhm's sensilla (Bs). Sensilla trichodea and basiconica were the most abundant sensilla types in the club flagellomeres. Mouth parts of R. dominica were adapted for chewing; maxillary and labial palpi consisted of four and five segments, respectively. Galea of maxilla was two segments, the distal one ended with a brush like organ composed of a dense field of long s. basiconica. The sensilla of maxillary and labial palpi were long and short s. trichodea, s. basiconica, s. styloconica and s. ampullacea. Only one big sensillum digitiformium was found on the lateral side of the distal segment of the maxillary palp.ConclusionsWe summarized the validated structures of different types of sensilla on antennae and palpi of R. dominica and proposed the potential functions of them in detection of ecologically relevant stimuli.

The Effect of Ozone on Rhyzopertha dominica, Tribolium Castaneum, and Technological Properties of Wheat Flour

ABSTRACT As an alternative to synthetic pesticides, ozone has been used to combat insects in stored grain. This study aimed to examine the lethal effect of a minimum dose and time combination on insects, the potential effect on insect spiracles and cuticles, as well as technological properties of wheat flour. At various exposure durations, ozone concentrations of 0.428 g/m3 (200 ppm) were used for 2, 4, and 6 h. Ozone gas was administered to the eggs, larvae, and adults of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). For R. dominica, adults were significantly more resistant to ozone gas than the larval and egg stages. For T. castaneum, adults and larvae seem to have a similar ozone susceptibility, and both were more resistant than eggs. This resistance was largely dependent on the insect species and exposure duration. The scanning electron microscope (SEM) showed multi-action on the cuticle, spiracles, and antennae of the insects treated by ozone. Wheat flour exracted from grains exposed to 0.428 g/m3 ozone for 6 h was subjected to further physiochemical analysis. Germination of ozone-treated wheat grains was 77%, compared to 83% of the untreated ones. The chlorophyll content of treated and untreated grains was 1.65 and 1.07 mg/g, respectively. The protein, fat, fiber, ash, and total carbohydrate contents of the ozone-treated samples (wholemeal and flour) did not differ significantly compared to the control. The rheological properties of wheat flour showed that ozone significantly decreased its water absorption (WA) from 56.21 to 55.81% while increasing dough development time (DDT) and dough stability time (DST). All sensorial parameters did not differ significantly between ozone-treated and untreated samples. Pan bread made from the flour of ozone-treated grains was fresher than the control bread.

Insecticidal Effect of Bularafa Raw Diatomaceous Earth (BRDE) Against Rhyzopertha dominica (F.) on Stored Maize (Zea mays L.) and Sorghum (Sorghum bicolor [L.] Moench) Grains

The toxicity of Bularafa raw diatomaceous earth (BRDE) to Rhyzopertha dominica adults on stored maize and sorghum grains was conducted under ambient laboratory conditions (31-34oC and 24 – 30% R.H.). The BRDE was tested at doses: 0 (untreated control), 250, 500, 1,000 1,500, and 2000 mg/kg and Protect-It® at 1000 mg/kg of grain which served as a check. Thirty (30) mixed-sex adult insects were exposed to 50 g of freshly treated grains, and mortality was observed after 7 and 14 days. The results showed that a higher number of exposed Rhyzopertha dominica adults died on maize than on sorghum, and mortality increased with an increase in dose and exposure period. After 7 days of exposure to treated maize and sorghum grains, the LD95 values were 4981 and 5890 mg/kg of BRDE, respectively. The corresponding values after 14 days were 1561 and 3206 mg/kg, respectively

Contact Toxicity of Hypericum Extracts against Rhyzopertha dominica (Fab.) (Coleoptera: Bostrichidae)

Medicinal and aromatic plants have popular recently to investigate their usability as natural resources in many areas due to their superior biological activity properties. Hypericum genus contained important medicinal plant species known worldwide. In this study, the ethanol extracts from different plant parts (flower, leaf and stem) of three Hypericum perforatum, Hypericum heterophyllum, Hypericum scabrum were screened for their toxicity against adults of Rhyzopertha dominica (Coleoptera: Bostrichidae), an important insect of stored grains in many regions of the world. Insecticidal activity was analysed at 10 % concentration of ethanol extracts, and measurements were taken at three different exposure times (24, 48 and 72 hours). Considering the factors analyzed on this insect, Hypericum species, plant part, exposure time as well as the interaction of Hypericum species and plant part displayed a statistically significant effect. The mortality values of extracts from H. perforatum, H. heterophyllum and H. scabrum varied from 44.8 % to 88.9 %, 26.0 to 78.8 %, 26.1 % to 50.3 % for adult of R. dominca, respectively, after 72 h. H. perforatum showed a stronger effect than other species. Among plant parts, the leaf showed superior mortality on this insect. In addition, the mortality rate increased with increasing exposure time. According to the interaction between Hypericum species and the plant part, the leaf of H. perforatum (79.4 %) displayed the strongest mortality, followed by the leaf of H. heterophyllum (70.6 %). After 72 hours, the highest mortality was recorded in the leaf parts of H. perforatum. The current results showed that the extracts, in particular, the leaf extracts of H. perforatum and H. heterophyllum, may be evaluated as a new natural potential product of plant-derived insecticide because of its high mortality impact against R. dominica.

Fumigation Monitoring and Modeling of Hopper-Bottom Railcars Loaded with Corn Grits

IntroductionBulk railcars are a common method of moving commodities in the USA. Allowances are given for the practice of treating railcars with fumigates during transit because the routes are limited access and not on public roads. Recent technology has become available for monitoring phosphine gas (PH3) fumigation on railcars which logs the phosphine concentration and temperature of the test point in the railcars.Materials and MethodsTwo hopper bottom railcar shipments of corn grit were monitored for phosphine during 8-day transit from mill to processor. Several phosphine-sensing units were used in each railcar and spaced across the top layer. Mathematical modeling of the railcar fumigation was carried out using computational fluid dynamic software. Because access to lower depths in the railcar was not available, supplement experiments were performed with small columns of corn grits (2.5 m height x 0.55 m diameter) to test for phosphine at greater depths. Also, in the grain columns, bioassays of both phosphine susceptible and resistant, adult Rhyzopertha dominica (F.), lesser grain borer, and Tribolium castaneum (Herbst), red flour beetle, were included at the 0 cm, 25 cm, and 60 cm below the surface.ResultsThe phosphine concentrations in the railcar headspace varied with time with phosphine spiking over 1600 ppm and gradually settling to over 300 ppm at the end of the 8 days. Total gas dosage was estimated as concentration*time (CT) over the 8 days as 115,000 and 125,000 ppm*h at the top of each railcar. The supplement grain column fumigation tests found significant phosphine penetration into the column at 2 m depth with ~380 ppm after 2 days which reduced to ~260 ppm after 8 days, and all insects, at all locations, were dead after 8 days. The CFD simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well with the observed data, validating the CFD approach as a useful tool.DiscussionThe simulation models were shown to provide estimates of the phosphine concentration and distribution which matched well the observed data, validating the CFD approach as an efficient tool for future planning and analysis of similar fumigations.

Chemical Profiles and Insecticidal Potential of Essential Oils Isolated from Four Thymus Species against Rhyzopertha dominica (F.).

Although chemical pesticides have been efficiently used to manage insect pest, their overuse has led to environmental contamination and threats to human health, enticing researchers to introduce eco-friendly and effective agents. In this study, the insecticidal effectiveness of essential oils isolated from Thymus species, including T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris, was evaluated against the adults of Rhyzopertha dominica. The terpenes p-cymene, 1,8-cineole, linalool, α-terpineol, and carvacrol were the prominent compounds in the hydrodistilled essential oils. All essential oils produced significant fumigant at 24, 48, and 72-exposure times. The energy reserves protein by all essential oils, glycogen by T. kotschyanus and T. vulgaris, and lipid by T. fallax and T. vulgaris were significantly decreased compared to control. All essential oils except T. vulgaris affected the amylolytic and proteolytic activity of the pest. The pest increased the α- and β-esterase enzyme activity in response to the essential oils. Nutritional indices of adults were also affected by essential oils, in which feeding deterrence index was calculated from 20.41% to 61.11%. Accordingly, based on lethal and extensive sub-lethal insecticidal activities, T. eriocalyx, T. kotschyanus, T. fallax, and T. vulgaris essential oils can be considered as efficient agents for R. dominica management.

Beauveria bassiana Konidilerinin Katı Faz Fermantasyonu ile Kitlesel Üretimi için Bazı Tahılların İncelenmesi

This study was conducted to test five substrates (whole rice, broken rice, dovme, wheat and burghul) for the mass production of Beauveria bassiana isolate 5-4, known to be affective against stored-cereal pests. A solid-state fermentation technique was used, and amount of product, number of conidia, germination, hydrophobicity and thermotolerance of conidia, and their virulence on Rhyzopertha dominica adults were used to evaluate the success of substrates. For production, 100 g of a substrate was used in a polypropylene bag. After sterilization and inoculation, the bags were sealed and incubated for 14 days at 25ºC. Hydrophobicity was assessed using the aqueous-solvent partitioning method with PM buffer, and liquid paraffin as two phases. Thermotolerance tests were conducted by exposing conidia to 35, 40 and 45°C for 15, 30 and 60 minutes. In virulence test, adults were released into 40 gr wheat mixed with conidia and kept at 25oC and 65% relative humidity in darkness for 14 days. The highest amount of product was obtained by using whole rice (4.10g/bag), followed by broken rice, wheat, dövme and burghul. The highest number of conidia was achieved using broken rice (10.24x1010conidia/g) and whole rice (9.62x1010conidia/g). The germination rates of conidia did not vary significantly. Significantly higher hydrophobicity rate was obtained using wheat (88.73%). The conidia from burghul and wheat showed higher thermotolerance than those from other substrates. The conidia obtained from whole rice and broken rice caused 80.3% and 72.0% mortalities, respectively, significantly higher than the others. Rice was found to be a better choice for this isolate as the ultimate purpose is to suppress pest populations, with awareness of its shortcomings. It was found crucial to test all important characteristics of produced conidia together for assessment of substrates.

Immediate and Delayed Mortality of Four Stored-Product Pests on Concrete Surfaces Treated with Chlorantraniliprole.

Simple SummaryWe examined the mortality caused by the anthranilic diamide, chlorantraniliprole, at four different doses applied on concrete (0.01, 0.05, 0.1, and 0.5 mg a.i./cm2) in Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) adults and larvae, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and Acarus siro L. (Sarcoptiformes: Acaridae) adults and nymphs. Mortality data were recorded after 1, 2, 3, 4, and 5 days to determine the immediate mortality. Furthermore, after the 5-day mortality counts, still living individuals were conveyed for 7 days to untreated concrete surfaces to estimate the delayed mortality. The highest immediate mortality was recorded for the larvae of T. castaneum, reaching 96.7%, followed by the adults of A. siro (92.2%) after 5 days of exposure to 0.5 mg a.i./cm2. Complete (100.0%) delayed mortality was noticed for T. castaneum (adults and larvae), S. oryzae, and A. siro (both as adults) at 0.5 mg a.i./cm2. Rhyzopertha dominica adults and A. siro nymphs exhibited 98.6% and 96.3% delayed mortality at the same dose, respectively. Overall, our results demonstrate that chlorantraniliprole is effective against all the species tested, causing varying immediate and delayed mortality rates at the developmental stages tested.Chlorantraniliprole is an effective pesticide against a plethora of pests, but its efficacy against stored-product pests is very poorly explored. In this study we treated concrete surfaces with four different doses of chlorantraniliprole (0.01, 0.05, 0.1, and 0.5 mg a.i./cm2) against the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) adults and larvae, the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae) adults, the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae) adults, and the flour mite, Acarus siro L. (Sarcoptiformes: Acaridae) adults and nymphs, to examine the immediate mortalities after 1, 2, 3, 4, and 5 days of exposure. Additionally, the delayed mortality of the individuals that survived the 5-day exposure was also evaluated after a further 7 days on untreated concrete surfaces. We documented high mortality rates for all tested species and their developmental stages. After 5 days of exposure to 0.5 mg a.i./cm2, T. castaneum larvae and A. siro adults exhibited the highest immediate mortality levels, reaching 96.7% and 92.2%, respectively. Delayed mortality was also very high for all tested species and their developmental stages. Nymphs of A. siro displayed a 96.3% delayed mortality followed by the adults of R. dominica (98.6%) after exposure to 0.5 mg a.i./cm2. All other tested species and their developmental stages reached complete (100.0%) delayed mortality, where even 0.01 mg a.i./cm2 caused ≥86.6% delayed mortality in all species and their developmental stages. Taking into consideration the effectiveness of chlorantraniliprole on this wide range of noxious arthropods, coupled with its low toxicity towards beneficial arthropods and mammals, this pesticide could provide an effective management tool for stored-product pests in storage facilities.

Studies on the application of bio-carbon dioxide as controlled atmosphere on pest management in wheat grain storage

The study evaluated the viability of purified waste gas called bio-CO2 (CO2 ≥ 98%, CH4 ≤ 2.0%, v/v), which is a byproduct from a compressed biogas (CBG) plant, as a new source of CO2 for control atmosphere for wheat grain storage. The findings were compared with the use of pure CO2 on mortality of Rhyzopertha dominica adults, seed germination, and nutritional quality of wheat grain for two and six months storage periods. Fifteen tapered plastic bottles of 1 L storage volume were taken for grain storage. Insect mortality of 100% was found in 1, 3, and 5 days using bio-CO2 and 4, 6, and 8 days with pure CO2 at 80, 60, and 40% concentration, respectively. In control grain infested with R. dominica, the adult insect triplicated in six weeks, 3.9 times in two months, and 10.4 times in 6 months storage. There were no significant differences (p > 0.05) observed in seed weight stored for two and six months under the bio-CO2 fumigation. Whereas, seed weight loss of about 5.03 ± 0.8% in control without infestation and 17.25 ± 1.2% in grain infested with R. dominica were reported over two months storage. Similarly, no weight loss during controlled atmosphere treatment, 12.66 ± 0.34% in control, and 27.42 ± 0.96% with R. dominica were found for six months storage period. The seed germination was significantly affected at 80% CO2 using both the controlled atmosphere for grain stored for six months. The major nutrient contents remained non-significant (p > 0.05) under both the fumigants. Whereas, carbohydrate content was significantly reduced (p < 0.05), and protein content was increased in control without infestation and grain infested with R. dominica.

Effect of thiamethoxam partial grain treatment to Rhyzopertha dominica (F.) and Sitophilus oryzae (L.) adults

The efficacy of partial treatment of two commodities (wheat and rice) with thiamethoxam against adults of Rhyzopertha dominica (F.) and Sitophilus oryzae (F.) was tested by mixing different proportions of thiamethoxam-treated and untreated grains. Thiamethoxam was applied to these grains in two different doses 1 and 5 ppm, while the percentage of the treated grain quantity ranged between 0 and 100%. Adult mortality was recorded after time exposure intervals of 7 and 14 d. Irrespectively of the dose, adult mortality was raised with increase in the percentage of treated kernels as well as the exposure time. Applications of thiamethoxam on wheat were more effective than on rice and on R. dominica than on S. oryzae, especially at 1 ppm, for both exposure intervals. The effective “critical” percentage, causing control similar to 100% treatment, of thiamethoxam to grain mass at 5 ppm was 50% for both species. For the examined scenario of partial treatment, thiamethoxam found to be effective against the tested species which makes it a candidate for use in the stored grain protection.

In package control of Rhyzopertha dominica in wheat using a continuous atmospheric jet cold plasma system

Cold plasma is recognized and explored for a plethora of applications in the food and agricultural industry. This study investigated the influence of a continuous atmospheric pressure non-thermal jet plasma system on the mortality of Rhyzopertha dominica adults in whole wheat kernels and the changes in the milling and physicochemical attributes of the treated whole wheat. Air-filled packets of whole wheat kernels were artificially infested with R. dominica adults. The packages were carried by a continuous conveyor belt and treated with plasma at voltages ranging from 44-47 kV for 4-7 min. The mortality was determined after 24 h and milling yield, particle size, proximate composition, and color of plasma-treated and untreated wheat grains were also evaluated. The maximum mortality was 88.33% at 47 kV for 7 min. The milling yield, protein, and fiber content of wheat were enhanced with plasma treatment significantly. Thus the continuous atmospheric pressure jet plasma used in this study could be one of the practically implementable emerging techniques for the commercial disinfestation of packaged food products.

Efficacy of layer grain treatment with thiamethoxam against adults of Rhyzopertha dominica (F.) and Sitophilus oryzae (L.)

The insecticidal effect of the neonicotinoid insecticide thiamethoxam, applied in layers of wheat, was studied in laboratory experiments, for the control of the lesser grain borer, Rhyzopertha dominica (F.) and the rice weevil Sitophilus oryzae (L.). In general, the increase of the size of the treated layer of wheat increased parental morality and decreased progeny production for both species. However, progeny production could not be totally avoided, even when the entire grain quantity was treated. Parental morality was lower for R. dominica than for S. oryzae, but the reverse was observed for progeny production for all treatments. Insect placement drastically affected thiamethoxam efficacy, since morality was generally higher when insects were forced to move downwards from the upper layer, as compared with insects that had been placed in the bottom part of the wheat column. Our study shows that thiamethoxam can reduce insect populations in partially treated wheat, at concentrations that are comparable with other, currently registered grain protectants.

Evaluation of dosimeter tubes for monitoring phosphine fumigations

Within integrated pest management options, fumigation of stored products is one method to help control post-harvest insect infestations in our food and agricultural products. Fumigant gas concentration monitoring is important to confirm that the treatment was adequate to achieve the desired insect control, but monitoring can be relatively expensive and labor intensive. This study evaluated how accurately dosimeter tubes could monitor phosphine fumigation treatments. The dosimeter tube is designed to continuously react with phosphine gas during the fumigation period and yields a measurement in terms of concentration ∗ time product or CT, which can be interpreted as cumulative exposure. Two models of dosimeter tubes were evaluated (high range and low range). The reference method for these trials were wireless phosphine monitoring sensors, which recorded gas concentrations at hourly intervals during an exposure, and from this a CT product was also calculated. Model LPG-1, high-range dosimeter tube, measured within ± 25% of the phosphine monitoring sensors for CT dosages less the 70,000 ppm∗hr. Model LPG-2, low-range tube, tended to significantly over-estimate phosphine CT dosage by 50%–100% of the phosphine monitoring sensor references. Secondly, bioassays of fumigant efficacy were performed using susceptible and resistant adult Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae), lesser grain borers, and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), red flour beetle, for estimating insect control at the varied fumigation CT treatments. For the susceptible strains, CT dosages ∼5000 ppm∗hr controlled both species. However, the insect control varied from 60% to 100% for resistant adults at CT dosages of ∼20,000 ppm∗hr. The dosimeter tubes function in these ranges of dosages where each insect species are controlled and the dosimeter tube model LPG-1 provides reasonable estimates of the fumigation dosage for a given treatment level.

Toxicity and physiological effects of essential Oil from Lavandula angustifolia (M.) against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) adults

Present study reports the chemical composition and the contact toxicity of Lavender derived essential oil and its effects on the biochemical composition (carbohydrates, lipids, ad proteins) and the antioxidant enzymes (SOD, CAT and GPx) in adults of Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae). Chemical composition analysed by gas chromatography-mass spectrometry (GC-MS) showed that Linalool (20.48%) and linalyl acetate (13.24%) were the major compounds. The EO exhibit contact toxicity against Rhyzopertha dominica, with dose-response relationship. Moreover, EO of L. angustifolia induce a decrease of the lipid, protein and carbohydrate contents in adults. Biomarkers determined in adults treated with LC25 and LC50 revealed an induction of the detoxification system via an increase in activity of Catalase and Superoxyde dismutase and no effect on GPx activity. L. angustifolia essential oil could be considered as alternative to chemical insecticides for pest control.