Weevil Sitophilus Oryzae Research Articles

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

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

Dependence of Uric Acid Content in Stored Grain on the Population Density of the Rice Weevil Sitophilus oryzae (L.) (Coleoptera, Dryophthoridae)

Experimental research demonstrated a positive linear correlation between the amount of uric acid, accumulated in stored wheat grain because of vital activity of the rice weevil Sitophilus oryzae, and the density of these weevils in grain.

Analysis of Pole-Ascending–Descending Action by Insects Subjected to High Voltage Electric Fields

The present study was conducted to establish an electrostatic-based experimental system to enable new investigations of insect behavior. The instrument consists of an insulated conducting copper ring (ICR) linked to a direct current voltage generator to supply a negative charge to an ICR and a grounded aluminum pole (AP) passed vertically through the center of the horizontal ICR. An electric field was formed between the ICR and the AP. Rice weevil (Sitophilus oryzae) was selected as a model insect due to its habit of climbing erect poles. The electric field produced a force that could be imposed on the insect. In fact, the negative electricity (free electrons) was forced out of the insect to polarize its body positively. Eventually, the insect was attracted to the oppositely charged ICR. The force became weaker on the lower regions of the pole; the insects sensed the weaker force with their antennae, quickly stopped climbing, and retraced their steps. These behaviors led to a pole-ascending–descending action by the insect, which was highly reproducible and precisely corresponded to the changed expansion of the electric field. Other pole-climbing insects including the cigarette beetle (Lasioderma serricorne), which was shown to adopt the same behavior.

Chemical compositions and insecticidal efficacies of four aromatic essential oils on rice weevil Sitophilus oryzae L

Plant essential oils contained secondary metabolite chemicals showing toxicities on stored grain insects. The main aims of this study was to evaluate the insecticidal efficacies and chemical compositions of essential oil from C. flexuosus, C. winterianus, C. martini, and P. cablin against Sitophilus oryzae (L.). The GC-MS analysis results showed that, the essential oils of four aromatic plants are rich in citral, neral, geranyl acetate, geraniol, citronellal, geraniol, citronellol, photocitral B, azulene and α-guaiene respectively. The essential oils of C. flexuosus with LC50 values are 44.5 and 26.1 μl/L air after 24 and 48 h exposure which was found to be most potent fumigant than C. winterianus followed by C. martini and P. cablin respectively. Further, in contact toxicity, C. martini oil being the most effective against adults of S. oryzae with LC50 values of 2.6 and 1.8 μl/cm2 after 24 and 48 h exposure respectively, whereas moderate toxicity was observed in S. oryzae from the essential oils of C. winterianus and P. cablin. These results suggested that the essential oils extracted from C. flexuosus, C. winterianus, C. martini, and P. cablin can be used as in the management of S. oryzae in order to decrease the harmful effects and risk of synthetic insecticides on human beings.

Screening of promising rice varieties against rice weevil (Sitophilus oryzae) under laboratory condition

The varietal screening of S. oryzae was studied on the rice grain and it was revealed that the minimum number of adult emergence was found in variety Swarna (3.33 adults) whereas variety MTU-1001 was found to be tolerant against S. oryzae with less per cent of grain damage (2.66%) and weight loss (1.00%). While the variety Dubraj Selection -1 was found highly susceptible to this pest in accordance to highest number of adult emergence (21.65 adults), maximum percent of grain damage (8.33%) and weight loss (6.66%), respectively.

Evaluation of edible and non-edible oils against rice weevil Sitophilus oryzae (L.) in stored paddy

Some edible and non edible oils were evaluated against the rice weevil Sitophilus oryzae (L.) infesting paddy during 2018–19 at the Biological control Laboratory and P.G. Research Laboratory, Department of Agricultural Entomology, N. M. College of Agriculture, Navsari Agricultural University, Navsari. The results indicate that significantly maximum mortality (79.58%) with minimum seed damage (2.56%) and weight loss (1.58%) was observed in the seeds treated with mustard oil @1% followed by castor oil (4.22%, 2.88%, 70%, respectively); and sesame oil at 1% was the least effective, resulting in maximum seed damage (9.93%), weight loss (6.40%) and the least mortality (52.09%).

Varietal resistance against Sitophilus Oryzae in rice

Fifteen varieties/genotypes were screened against the rice weevil Sitophilus oryzae (L.) during 2018–19 at the Biological Control Laboratory and P.G. Research Laboratory, Department of Agricultural Entomology, N. M. College of Agriculture, Navsari Agricultural University, Navsari. The varieties GR-7, GNR-7 and IR-28 were observed to show maximum resistance, as indicated by minimum seed damage, weight loss, more germination and less population buildup while, the genotype GNR-4 was the most susceptible.

Biology of rice weevil Sitophilus oryzae (L.)

Biology of the rice weevil Sitophilus oryzae (L.) was studied on the rice variety Jaya under laboratory condition at the P.G. Research Laboratory, Department of Agricultural Entomology, N. M. College of Agriculture, Navsari Agricultural University, Navsari. The duration of first, second, third, fourth instar larvae and pupa was 5.92 ± 0.70, 6.64 ± 0.49, 8.04 ± 0.73, 5.36 ± 0.70 and 6.48 ± 0.51 days, respectively. The preoviposition, oviposition and postoviposition periods were 3.79 ± 0.66, 54.80 ± 3.93, 19.88 ± 2.62 days, respectively; and fecundity observed at 288 to 389 (352.68 ± 28.84). The adult females survived for 72.36 ± 3.54 days while, males survived for 50.68 ± 2.97 days with food; without food it was 8.6 ± 0.82 and 5.8 ± 0.82 days, respectively. The total lifecycle was 83.12 ± 4.43 days (male) and 110.8 ± 3.35 days (female) with food.

Россию настигла резистентностъ насекомых к фосфину

For the first time, increased resistance to phosphine in the wild population of rice weevil Sitophilus oryzae in Russia has been reported compared to the beetles of laboratory population with a resistance factor of 2.5.

Assessment of the Toxicity of Natural Oils from Mentha piperita, Pinus roxburghii, and Rosa spp. Against Three Stored Product Insects

Three natural oils extracted from Mentha piperita, Pinus roxburghii, and Rosa spp. were assessed in order to determine their insecticidal activity against the adults of three stored product insects: the rice weevil (Sitophilus oryzae L.), the lesser grain borer (Rhyzopertha dominica, Fabricius), and the red flour beetle (Tribolium castaneum, Herbst.). By Gas chromatography–mass spectrometry (GC/MS) analysis, the main compounds in the n-hexane oil from Rosa spp. were determined to be methyl eugenol (52.17%), phenylethyl alcohol (29.92%), diphenyl ether (7.75%), and geraniol (5.72%); in the essential oil from M. piperita, they were menthone (20.18%), 1,8-cineole (15.48%), menthyl acetate (13.13%), caryophyllene (4.82%), β-pinene (4.37%), and D-limonene (2.81%); and from the foliage of P. roxburghii, they were longifolene (19.52%), caryophyllene (9.45%), Δ-3-carene (7.01%), α-terpineol (6.75%), and γ-elemene (3.88%). S. oryzae and R. dominica were reared using sterilized wheat grains, and T. castaneum was reared on wheat flour mixed with yeast (10:1, w/w), all under laboratory conditions (27 ± 1 °C and 65% ± 5% Relative humidity (R.H). Two toxicity bioassays were used, as well as contact using thin film residues and fumigation bioassays. The results indicated that M. piperita caused a high toxicity for S. oryzae compared to other insects. High significant variations were observed between the tested M. piperita doses against the stored insects, and this natural material could be used to control insects that infect the grains. Also, the data indicated that the Rosa spp. oil had a low-toxicity effect against these insects compared to other oils. We recommend using natural oils against the stored weevils and petals, rather than the chemical agent, so as to serve human health.

Minimization of energy transduction confers resistance to phosphine in the rice weevil, Sitophilus oryzae

Infestation of phosphine (PH3) resistant insects threatens global grain reserves. PH3 fumigation controls rice weevil (Sitophilus oryzae) but not highly resistant insect pests. Here, we investigated naturally occurring strains of S. oryzae that were moderately resistant (MR), strongly resistant (SR), or susceptible (wild-type; WT) to PH3 using global proteome analysis and mitochondrial DNA sequencing. Both PH3 resistant (PH3–R) strains exhibited higher susceptibility to ethyl formate-mediated inhibition of cytochrome c oxidase than the WT strain, whereas the disinfectant PH3 concentration time of the SR strain was much longer than that of the MR strain. Unlike the MR strain, which showed altered expression levels of genes encoding metabolic enzymes involved in catabolic pathways that minimize metabolic burden, the SR strain showed changes in the mitochondrial respiratory chain. Our results suggest that the acquisition of strong PH3 resistance necessitates the avoidance of oxidative phosphorylation through the accumulation of a few non-synonymous mutations in mitochondrial genes encoding complex I subunits as well as nuclear genes encoding dihydrolipoamide dehydrogenase, concomitant with metabolic reprogramming, a recognized hallmark of cancer metabolism. Taken together, our data suggest that reprogrammed metabolism represents a survival strategy of SR insect pests for the compensation of minimized energy transduction under anoxic conditions. Therefore, understanding the resistance mechanism of PH3–R strains will support the development of new strategies to control insect pests.

Insecticidal Effects of Fumigants (EF, MB, and PH3) towards Phosphine-Susceptible and -Resistant Sitophilus oryzae (Coleoptera: Curculionidae).

This study was conducted to evaluate the insecticidal effects of ethyl formate (EF), methyl bromide (MB), and phosphine (PH3) fumigants against PH3-susceptible and -resistant strains of the rice weevil (Sitophilus oryzae), a major rice pest. The highest lethal concentration time 50 (LCt50) values of the PH3-susceptible strains were 255.797, 21.104, and 6.171 mg h L−1 for EF, MB, and PH3, respectively, at pupal stage. The highest LCt50 values of the PH3-resistant strains were 149.028 and 48.170 mg h L−1 for EF and PH3, respectively, at late larval stage, and 43.520 mg h L−1 for MB at pupal stage. In comparison to the susceptible strains, the PH3-resistant strain collected in South Korea had a resistance level 4 to 56 times higher. Use of the major quarantine fumigants EF, MB, and PH3 indicated the existence of PH3-resistant rice weevils in South Korea for the first time.

Morphological, biochemical, molecular, and oil toxicity properties of Taxodium trees from different locations

Taxodium is a deciduous conifer belong to family Cupressaceae, commonly known as cypresses. In the present study, two species of Taxodium trees from four locations in Egypt were investigated. Bald cypress and pond cypress as plant genetic resources were surveyed and tested for horticultural and morphological traits using biochemical and molecular genetic techniques. Leaf essential oils (EOs) were analyzed by gas chromatography coupled with mass spectrometry (GC/MS), subjected to bioassay for insecticidal activity against the rice weevil (Sitophilus oryzae L.) and the red flour beetle (Tribolium castaneum (Herbst)), and compared with three monoterpenes (D-limonene, camphor, and carvone). T. distichum var. distichum (bald cypress) growing in the drylands in the Alexandria, El-Beheira, Giza 1, and Qalyubia governorates had lower root hydrogen peroxide (H2O2), proline content, and leaf peroxidase activity than T. distichum var. imbricarium (pond cypress, Giza 2), growing in swamplands of the Giza governorate. Forty random amplified polymorphic DNA (RAPD-DNA) primers and 20 simple sequence repeats (SSRs) indicated 57.41% and 64.50% polymorphism, respectively, between the Taxodium species. The main constituents of leaf EOs from trees growing in Alexandria were germacrene D (14.71%), borneol acetate (6.81%), ledene oxide-(II) (6.13%), and trans(β)-caryophyllene (6.13%); thujopsene (18.27%), 3-carene (14.49%), and cedrol (8.02%) were found in trees from Qalyubia; thujopsene (19.93%), α-caryophyllene oxide (17.32%), and cedrol (10.87%) from trees in Giza 1, α-pinene (63.80%) and thujopsene (10.15%) from trees in Giza 2, and El-Beheira α-pinene (26.66%), thujopsene (22.42%), and cedrol (11.30%) in trees from El-Beheira. S. oryzae was more susceptible than T. castaneum to the EOs from leaves of Taxodium trees from the four localities. Taxodium oil from El-Beheira followed by carvone and EOs from trees grown in Alexandria showed the lowest LC50 against S. oryzae with values of <50, 28.52, and>50 μL/L, respectively. Carvone, Taxodium EOs from El-Beheira and Qalyubia exhibited the lowest LC50 against T. castaneum with values of 53.37, 66.40, and 72.54 μL/L, respectively.

Repellent Activity of Waste Extract from Two Local Medicinal Plant Against Rice Weevil (Sitophilus oryzae)

In order to find natural and inexpensive bioinsecticides, the active compound of waste extract from two medicinal plants were analyzed. Ethanolic extracts of Amomum cardamomum and Zingiber zerumbet were evaluated under laboratory conditions for their repellency against rice weevil (Sitophilus oryzae, L.). Four extracts concentration were tested in this research, i.e: 25, 50, 75 and 100%. Efficacy was measured based on the response of rice weevil in preference tests using Y Olfactometer Tube, then the results were converted into the Percentage Repellency (PR) and Preference Index (PI). The PR data were analyzed using ANOVA, whereas PI values were analyzed descriptively. The result showed that the PR were significantly (LSD test; α&gt; 0.05) and revealed that waste extracts repel the rice weevil at 100% solution. The highest PR was found at 100% solution in both extracts, however, statistically the repellency of A. cardamomum waste extract was higher than Z. zerumbet’s. Likewise, the PI of both extracts showed negative value at 75 and 100% concentration. This study concluded that extract of A. cardamomum and Z. zerumbet wastes have repellent effect against rice weevil and A. cardamomum repellency is better than Z. zerumbet. The findings of this study can provide a useful information for development of a rice weevil repellent extracted from waste product of medicinal plants that is more economically and environmentally friendly than synthetic insect repellents.

Effects of zeolite formulations on the mortality and progeny production of Sitophilus oryzae and Oryzaephilus surinamensis at different temperature and relative humidity levels

The insecticidal potential of two natural zeolite formulations, Zeocem and Mycostop, was tested against the rice weevil Sitophilus oryzae (L.) and the sawtoothed grain beetle Oryzaephilus surinamensis (L.) on wheat, at the dose rates of 0.25, 0.50, 0.75, and 1 g/kg. The bioassays were carried out under laboratory conditions at three temperature levels (20, 25, and 30οC) and two relative humidity (r.h.) levels (55, 75%). Mortality was recorded after 7, 14, and 21 d of exposure and progeny production was recorded 65 d later. Complete (100%) mortality was achieved only for O. surinamensis adults with Zeocem for most temperature and r.h. combinations tested. Progeny production for this species was extremely low. In contrast, mortality for S. oryzae was much lower and did not exceed 87% after 21 days at any of the combinations tested, while progeny production was high. For O. surinamensis exposed to Mycostop, mortality after 21 days did not exceed 97% for all temperature and r.h combinations, while overall progeny production was low. Moreover, S. oryzae mortality was generally low and did not exceed 56%, while progeny production for this species was high for most temperature and r.h. combinations. Despite the fact that some general trends were evident, the effect of temperarature and r.h. in zeolite efficacy was often found inconclusive. The results of the present study illustrated the insecticidal potential of zeolites for the contol of certain stored product insect species, which requires additional investigation.

Phytochemical-based nano emulsions for stored grain protection:

Stored grain losses caused by pest insects contribute significantly to the global food crisis. Currently, there are two main chemical control methods against stored product insect pests: fumigation with very toxic gases and grain protection by residual contact insecticides. Today, the global tendency is to prevent/reduce the wide use of insecticides, which have high toxicity to humans and harm the environment. Therefore, there is an urgent need to develop alternative eco-friendly approaches for stored insect pest control. Essential oils from Micromeria fruticosa and Mentha rotundifolia (Fam. Labiatae) and their main constituent pulegone which previously were shown by us as very active against stored product insect pests, were encapsulated into coarse and nano emulsions. The insecticidal activity of the developed formulations against primary internal insect rice weevil (Sitophilus oryzae L.) and secondary external pest red flour beetle (Tribolium castaneum Herbst) was evaluated in laboratory and pilot experiments. It was found that the phytochemical-based nano emulsions offered significant advantages and provided powerful and prolonged biological activity compare with the coarse formulations. The developed nano emulsions could serve as a natural, effective, low-toxify for human, and environmentally preferred method for protection stored grain and dry food products from pest insects.

Computational modeling and functional characterization of a GgChi: A class III chitinase from corms of Gladiolus grandiflorus

The present study describes the predicted model and functional characterization of an endochitinase (30 kDa) from corms of Gladiolus grandiflorus. ESI-QTOF-MS generated peptide showed 96% sequence homology with family 18, Class III acidic endochitinase of Gladiolus gandavensis. Purified G. grandiflorus chitinase (GgChi) hydrolyzed 4-methylumbelliferyl β-d-N,N′,N′′-triacetylchitotriose substrate showing specific endochitinase activity. Since no structural details of GgChi were available in the Protein Data Bank (PDB), a homology model was predicted using the coordinate information of Crocus vernus chitinase (PDB ID: 3SIM). Ramachandran plot indicated 84.5% in most favored region, 14.8% in additional and 0.6% in generously allowed region while no residue in disallowed region. The predicted structure indicated a highly conserved (β/α)8 (TIM barrel) structure similar to the family 18, class III chitinases. The GgChi also showed sequence and structural homologies with other active chitinases. The GgChi (50 μg/disc) showed no antibacterial activity, but did provide mild growth inhibition of phytopathogenic fungus Fusarium oxysporum at a concentration of 500 μg/well Similarly, insect toxicity bioassays of GgChi (50 μg) against nymphs of Bemisia tabaci showed 14% reduction in adult emergence and 14% increase in mortality rate in comparison to control values. The GgChi (1.5 mg) protein showed significant reduction in a population of flour beetle (Tribolium castaneum) after 35 days, but lower reactivity against rice weevil (Sitophilus oryzae). The results of this study provide detai.led insight on functional characterization of a family 18 class III acidic plant endochitinase.

Effect of paddy variety, milling status and aeration on the progeny emergence of Sitophilus oryzae L. (Coleoptera: Curculionidae)

In Sri Lanka, insects cause enormous losses in stored paddy; the rice weevil Sitophilus oryzae is a devastating insect. The magnitude of losses in stored paddy caused by insects varies with characteristics of paddy but has not yet been fully investigated. Due to the increased concerns on the use of synthetic chemicals, safer alternative pest management strategies for stored paddy are needed. Objectives of this study were to determine the effect of paddy variety, milling status and nature of aeration on the progeny emergence of S. oryzae. The experimental design was a three-factor factorial, completely randomized design (CRD).Freshly emerged S. oryzae adults were introduced to un-milled paddy or milled/polished rice belonging to traditional and improved varieties. The samples were maintained either open or airtight, and the progeny adults emerged was determined at monthly intervals. Progeny emergence was lower in the traditional varieties, un-milled paddy and under air-tight condition compared to improved varieties, milled/polished rice and aerated samples, respectively. Overall, the improved variety Bg 300 exhibited the maximum resistance to infestation by S. oryzae. Furthermore, white-colour and long-grain varieties produced lower progeny of S. oryzae than red-colour and short-grain varieties, respectively. It is concluded that the maximum protection in paddy/rice from insect infestation during storage can be achieved by using traditional varieties, stored as un-milled paddy (without dehusked) under airtight condition.

Effect of Grain Infestation with the Rice Weevil Sitophilus oryzae L. (Coleoptera, Dryophthoridae) on the Quality of Grain and Grain Products

The paper presents the results of experimental assessment of the quality parameters of wheat grain infested with the rice weevil Sitophilus oryzae and of flour and bread produced from this grain. The most important and the least stable parameters were the flour yield, ash content, whiteness, and fat acidity value. The infested grain had higher densities of micrococci, yeast, Aspergillus glaucus, and A. candidus.

Male multiple matings and reproductive success in commodity-adapted strains of Sitophilus oryzae

Multiple matings occur in many species of stored-grain insect pests, such as the rice weevil Sitophilus oryzae (L.), with both female and male mating more than once and with more than one partner. Multiple female mating in S. oryzae increased lifetime fecundity by extending the period of time progeny were produced, but consequences of multiple male mating in S. oryzae were not yet studied although it is likely to increase male fitness by increasing offspring production. Here, the effects of polygynous mating on male mating behavior, success, and fitness were assessed in two strains of S. oryzae, one adapted to barley and another to wheat. Two insect strains were considered because they may differ in response depending on the host grain, which present distinct nutritional value to the insects. Mating by pairs formed between the two strains did not impact mating success, but wheat-adapted females exhibited longer mating duration, which was positively correlated with progeny production. Wheat-adapted males exhibited higher fertility than barley-adapted males. When male multiple matings were considered in successive polygynous matings, late matings led to lower non-cumulative values of progeny production, but higher cumulative performance, and wheat-adapted S. oryzae always performed better. Thus, male fitness and grain losses in wheat are higher than in barley, even when S. oryzae was adapted to the latter.