Control Of Stored Grain Pests Research Articles

Aluminum accumulation in the wheat production chain: a review

The consumption of food containing significant amounts of aluminum has been the focus of discussions related to health. Aluminum is distributed in nature and may be naturally present in raw materials or added to food as a result of activities or modification processes along the food production chain. This exploratory and descriptive research identified possible sources of aluminum in food, in general, and particularly in the wheat chain and its derivatives, which comprise an important class in the food chain and ordinary consumption in many cultures. Even though total aluminum values have been found in food, in general, and particularly in wheat derivatives, information about their origins is still incipient. The total content of this metal in the food may be the result of a sum of sources. For wheat and its derivatives, the potential origins are among environmental factors, such as soil and water, and even operational procedures, such as the use of food additives and chemical compounds for the control of stored grain pests. Despite these considerations, the actual contributions of each source are still purely speculative, since although aluminum contents have been quantified in most studies, their sources were impartially explored and clarified.

Ozone reduces lifespan and alters gene expression profiles in Rhyzopertha dominica (Fabricius).

Rhyzopertha dominica is one of the most important stored grain pests that seriously damage rice and wheat. At present, the method of controlling stored grain pests mainly relies on insecticide fumigation. However, the excessive use of pesticides not only leaves pesticide residues, with harmful effects on human health and the environment, but also induces insect resistance. Ozone is a strong oxidant with the characteristics of easy decomposition and without residue. Although ozone has been widely used in the food industry in recent years, research on the control of stored grain pests is limited. In this research, we used ozone treatment to control R. dominica adults and explore the molecular mechanisms that affect them. Here, we found that ozone treatment on R. dominica adults could decrease life span and increase malondialdehyde (MDA) content, as well as reduce activity of total superoxide dismutase (SOD) and catalase (CAT). Using RNA-seq technology, we identified 641 genes that were differentially expressed between ozone-treated and control R. dominica adults [fold-change of ≥ 2 (q-value < 5%)]. When comparing ozone treatment with control R. dominica adults, 330 genes were significantly upregulated and 311 were downregulated. RT-qPCR confirmed that 11 genes were differentially expressed in ozone-treated and control R. dominica adults. These genes were involved in insect cuticle protein and antioxidant system. This research showed that ozone treatment could reduce the lifespan of R. dominica through antioxidant system. It is an environmentally benign method for the control of stored grain pests and has great development potential.

Characteristic and expression of Hsp70 and Hsp90 genes from Tyrophagus putrescentiae and their response to thermal stress

The development of insects is critically affected by temperature, which therefore plays an important role in the control of stored grain pests. Extreme temperature stress conditions lead to biological responses in mites, such as the synthesis of heat shock proteins. Tyrophagus putrescentiae (Tp) is a pest mite in stored grain that has negative effects on both economy and health. Since T. putrescentiae population dynamics are strongly influenced by temperature, in the present study we have cloned the cDNA of HSP70 and HSP90 (referred to as TpHSP70-1, TpHSP70-2 and TpHSP90) and determined their expression by fluorescence real time quantitative PCR. TpHSP70 and TpHSP90 showed high homology with similar genes in other species and the open reading frames of TpHSP70-1, TpHSP70-2 and TpHSP90 encoded proteins of 665, 661 and 718 amino acid residues, respectively. Under thermal stress, expression of TpHsp70-1 and TpHsp90 was up-regulated at higher temperatures, suggesting their role in the defense against thermal stress.

Comparative Insecticidal Activity of Three Forms of Silica Nanoparticles on some Main Stored Product Insects

The control of stored grain pests requires effective materials that are save for humans and environment, low cost, available and easy to obtain and do not need trained labor. Therefore, the current study suggested testing three silica forms in the form of nanoparticles, these were Aerosil 200, chemical and bio-silica for controlling Callosobrochus maculatus F. (Col., Bruchidae), Rhythopertha dominica fab, and Tribolium confusum (Jacquelin du Val). The obtained results showed that the percent mortality increased with the increasing of concentration and exposure period. Moreover, all the tested materials of nanoparticles had detrimental induction on mortality and offspring of the three tested insects. In addition the adults of C.maculatus were more susceptible followed by R.dominica and T.confusum with the three tested materials at the all concentrations used. Data obtained revealed that the activity of chemical silica had the first rank followed by Aerosil 200 and bio-silica where the LC50 of chemical silica ranged between 0.14-1.54 one day posttreatment with significant distinction compared to Aerosil 200 (0.15-2.65) and bio-silica (2.43-7.35)g/kg grain. The findings obtained showed that the three forms of silica had deterrent action on the all tested immature stages at the all levels of concentrations. Also results clarified the egg stage was the most susceptible compared to larvae and pupae ones. The all treatments reduced the emerged adults and the losses of grain weight. Consequently the present study explained that the three used forms of silica are promising materials for controlling the tested insects as safe alternatives to the synthetic insecticides.

Evaluating the combination of Metarhizium anisopliae and an enhanced form of diatomaceous earth (Grain-Guard) for the environmentally friendly control of stored grain pests.

Stored grain pests cause great damage to various grain products, and protection against these pests is currently based on synthetic insecticides and fumigants. As a result, these chemicals cause problems, including grain contamination with chemical residues and the development of resistance by insect pests to these chemicals. Therefore, to combat this issue, in the present study, an enhanced form of diatomaceous earth (DE), Grain-Guard, and Metarhizium anisopliae (Metschnikoff) Sorokin (Ascomycota: Sordariomycetes) were evaluated alone and in combination against adults of Liposcelis paeta (Pearman) (Psocoptera: Liposcelididae), Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae), Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), and Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). M. anisopliae was used at a rate of 1.7 × 104 conidia kg-1 grain alone as well as with two doses of DE (25 and 50ppm) on wheat under different exposure time courses (4, 7, and 14days). It is worth mentioning that the combination of M. anisopliae and DE was highly effective against the adults of L. paeta, C. ferrugineus, R. dominica, and T. castaneum after 14days of exposure. When DE and M. anisopliae were applied alone, DE showed more effectiveness than fungal conidia. Progeny emergence was decreased when modified DE was applied at a high dose rate with the fungus and suppressed at a low dose. The cadavers of all species in the trials showed a maximum percentage of mycosis, and sporulation (conidia/ml) also showed the same result when the fungus was tested alone, while low mycosis and sporulation were achieved under the application of a mixture with a high dose of modified DE. Our findings indicate the best possible combination of DE (at low dose rates) along with a fungus that might contribute to lowering health and environmental risks.

Toxicity of the essential oil of basil cultivars and hybrids and its repellent effect on stored grain pests

Essential oils have emerged as an alternative to synthetic insecticides in the control of stored grain pests. The toxicity and repellency of the essential oils of four basil cultivars and three basil hybrids and the monoterpenes linalool, citral, and (E)-methyl cinnamate were evaluated in the stored grain pests Callosobruchus maculatus and Sitophillus zeamais. The essential oils of the cultivar Genovese and the hybrid 'Genovese' x 'Maria Bonita' were more toxic to C. maculatus. Conversely, the essential oils of the cultivar Sweet Dani and the hybrid 'Cinnamom' x 'Maria Bonita' were more toxic to S. zeamais. Among the monoterpenes, (E)-methyl cinnamate was the most toxic to both pests, taking 0.14 and 0.34 µL.mL-1 to kill 50% of the C. maculatus and S. zeamais populations, respectively. All essential oils from cultivars, hybrids, and monoterpenes were repellent to S. zeamais, except for (E)-methyl cinnamate. For C. maculatus, this effect was lower, being citral the most repellent compound. Results demonstrate the insecticidal potential of the essential oil of O. basilicum and its monoterpenes in the control of stored grain pests.

Chemical composition and insecticidal effect of essential oils from Illicium verum and Eugenia caryophyllus on Callosobruchus maculatus in cowpea

The cowpea weevil Callossobruchus maculatus Fabr. (Coleoptera: Chrysomelidae: Bruchinae) is the major pest in stored cowpea, especially in subtropical countries. Thus, the present study aimed to evaluate the insecticidal potential of the essential oils of Illicium verum Hook. F. and Eugenia caryophyllus Spreng on adults of C. maculatus. The components of the essential oils were obtained and identified, the contact toxicity and the repellent and fumigant effect were determined. In the contact and fumigation test the lethal concentrations LC50 and LC95 were determined, the lethal concentrations determined in the contact test were used in the repellency test. For contact and repellency tests, the number of eggs and adults emerged were counted. According to the chemical analysis of the oils, E-anethole (88.85 %) and eugenol (74.31 %) for I. verum and E. caryophyllus, respectively, were the compounds in greater quantity. The values of lethal concentrations LC50 and LC95 in the contact test were estimated at 9.62 and 32.78, 1.27 and 11.95 μL/20 g, respectively, for the oils of I. verum and E. caryophyllus. The essential oil of E. caryophyllus presented higher toxicity for both lethal concentrations, being 5.44 and 2.74 times more toxic than I. verum for LC50 and LC95, respectively. In contact and repellency tests both oils reduced the number of eggs and insects emerged. The LC95 concentration for both oils was repellent to C. maculatus. The essential oils of E. caryophyllus and I. verum presented a potential fumigant effect on C. maculatus with relatively low lethal concentration (LC50) (22.36 and 20.27 μL/L of air for I. verum and E. caryophyllus, respectively), thus being an alternative to synthetic chemical insecticides for the control of stored grain pests.

General Article: Views and Analysis Potential of bioactive products for the control of stored grain pests

The storing of grains has always been a problem for the farmers as various pests are commonly encountered in Assam and North East India. Infestation by these pests always causes great economic loss to the farmers every year. Various bioactive products has been known to have insecticidal property to great extent. Replacement of chemical pesticides by various bioactive products will be beneficial for the proper preservation of grain and are likely to cause less ecological damage. The use of synthetic products for the control of insect pests leads to the events like pest resistance, resurgence, product residues, undesirable environmental persistence, the risk to non-target organisms etc. Plant-derived bioactive compounds can be used as an alternative to control insect pest. Various phytochemicals include alkaloids, glycosides, terpenoids, saponins, flavonoids, phytosterols, phenolic compounds, steroids, ceramics, quinones, ethereal oils, propanoic derivatives, isoprene derivatives etc. are known to have an insecticidal activity to a varying degree.

Effectiveness of binary combinations of Plectranthus glandulosus leaf powder and Hymenocardia acida wood ash against Sitophilus zeamais (Coleoptera: Curculionidae)

BackgroundBotanicals are generally assumed to be more biodegradable, leading to less environmental problems. Combination of botanicals could enhance biological activity against insect pests. Hence, the amount of botanical used for the control of stored grain pests may be minimised. In this study, the bioassay was carried out on Sitophilus zeamais to assess the effectiveness of binary combinations of Hymenocardia acida wood ash and Plectranthus glandulosus leaf powder. The quantities of mixed products were added to maize grains to constitute the contents of 5, 10, 20 and 40 g/kg. Then, the bioassays on toxicity within 1, 3, 7 and 14 days exposure, progeny production, population increase, grain damage and germination ability of protected grains were carried out.ResultsThe major compounds (pinene, α-pinene, α-terpineol, thymol, β-myrcene and 3-carene) of P. glandulosus leaf powder were monoterpenes. The major non-monoterpenic constituent was an oxygenated sesquiterpene, β caryophyllene oxide. The chemical analysis of H. acida ash showed that calcium (5800 mg/kg) and phosphorus (2782 mg/kg) recorded higher content than the other minerals. Plectranthus glandulosus leaf powder, H. acida wood ash and their binary combinations significantly induced mortality of S. zeamais adult (P < 0.0001). The higher mortality rate was achieved by the highest content within 14 days of exposure. The combinations of P. glandulosus leaf powder with H. acida at different proportions produced different interactions. The mixture of 75% P. glandulosus and 25% H. acida produced synergistic effect, whereas the mixture of 50:50 had antagonistic effect in weevil mortality. The three combinations of H. acida and P. glandulosus significantly reduced the production of the progeny compared to the control. From the application of 5 g/kg (lowest content), the number of emerging adults was highly reduced. The combination 25PG75HA revealed to be more effective than the two other against F1 production. The grain damage and population growth were significantly reduced. In general, the non-infested maize grain had a good germination rate than the infested ones. The treatment did not have negative effect on seed germination.ConclusionsFrom our results, the two powders and their binary combinations could be used to reduce grain infestation by insect while taking into account the proportions of insecticidal powders implied in the combination.

Transcriptomic alterations in Sitophilus zeamais in response to allyl isothiocyanate fumigation

To study the fumigation mechanisms of Allyl isothiocyanate (AITC) a promising biorational alternative to present fumigants (phosphine and methyl bromide), and provide theoretical basis for its further development in the control of stored grain pests, this research presents a transcriptome analysis of Sitophilus zeamais fumigated with AITC at the concentration of LC50 (5.69μg/mL) and control over 8h. 21,869,022 and 23,873,110 clean reads in insects fumigated with AITC and control were gained, respectively. The results of RNA-seq were confirmed by qRT-PCR determination of the expression levels of NADH dehydrogenase subunit 6 and Vacuolar ATP synthase subunit B in the insects fumigated with AITC at different concentrations. After enrichment analysis of differentially expressed genes, 117 over-expressed and 271 down-regulated transcripts were gained. Following GO enrichment, these transcripts were classified into 38 GO subgroups (at level 2), and the majority enriched GO terms were “Binding” “Cell process” and “metabolic”. KEGG enrichment analysis showed that the majority enriched pathway were “Folding, sorting and degradation”, “Transport and catabolism”, “Energy metabolism”, and “Carbohydrate metabolism”. Connected with previous researches on mechanisms of isothiocyanates, cytoskeleton collapse and mitochondria dysfunction are proposed to be significant lethal mechanisms of AITC.

Fumigation with phosphine - a perspective

Phosphine evolved from metal phosphide preparations play a major role in the control of stored grain pests mainly because of cost factor and non-availability of suitable alternatives. Achieving target concentration is dependent upon dosage applied, exposure period and standard of gas tightness. MLCL gas proof covers of 150 GSM/200 GSM are considered more suitable for good phosphine retention as compared to HDPE and LDPE. Monitoring phosphine concentration is very important to ascertain the achievement of target concentration and to predict success of treatment before termination of fumigation. Application of improved fumigation standards, following gas tightness and monitoring of phosphine concentration can definitely help in delaying further development of insect resistance. This calls for active collaboration of industry, researchers and users of phosphine to prolong effective life of phosphine.

Influence of temperature on the functional response of Anisopteromalus calandrae (Hymenoptera: Pteromalidae), a parasitoid of Rhyzopertha dominica (Coleoptera: Bostrichidae)

The functional response of Anisopteromalus calandrae (Howard) parasitizing 4th-instar Rhyzopertha dominica (F.) on wheat was estimated over a range of temperatures and host densities. A functional response equation was used in which a quadratic component that included temperature was substituted for handling time. The instantaneous search rate increased with increasing temperatures. The maximum rate of parasitization was 13 larvae/24 h at 30°C and 35°C. Handling time was lowest at 30°C and highest at 20°C. The ability of A. calandrae to find and parasitize R. dominica over a broad range of temperatures makes it a good candidate for natural control of stored grain pests.

The effect of different formulations of B eauveria bassiana on S itophilus zeamaisin stored maize

Beauveria bassiana conidia were formulated as a dustable powder (DP), as oil suspensions (OS) and as a novel hydrogenated rapeseed oil pellet. These formulations were assessed against Sitophilus zeamais Motsch. to study their potential use in the control of stored grain pests. Conidial viability was maintained well in the fat pellet formulation (84.7% germination after 45 days storage at 25°C) and in the DP (83.3%), but less well in the OS formulation (55.3%). Twenty four hours of direct contact of S. zeamais with the fat pellet formulation containing 10 10 conidia/g gave 100% mortality after 7 days. Mineral oil and a mineral and maize oil mixture, without conidia, or as OS with B. bassiana at a concentration of 10 9 conidia/ml (both at 20 ml/kg grain) showed the highest level of control in maize grains; the oils alone were insecticidal and gave an oily appearance to the grain; there was a small but significant effect of adding B. bassiana to the mineral and maize oil mixture applied at 5 ml/kg of grain. There was no benefit of adding conidia with those treatments. The DP formulation achieved up to 90% control after 15 days at 25°C with an application of 20 g of DP per kg of maize (2×10 10 conidia/kg maize), and 77.5% with a dose of 5 g/kg (5×10 9 conidia/kg maize). The fat pellet formulation resulted in low levels of mortality (21–31%) when used in maize grains.