Demographic responses of Tribolium castaneum (Coleoptera: Tenebrionidae) to different temperatures in soft wheat flour.

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is one of the most dangerous insects of a wide spectrum of stored products around the globe. The population growth of this species is affected by temperature. However, there are no data on comparative demographic parameters (i.e., net reproductive rate, intrinsic rate of increase, finite rate of increase, mean generation time and doubling time) in different temperatures, parameters that allow the in-depth exploration of its survival, mortality and reproduction patterns. This study evaluated egg-to-adult development, adult mortality and female fecundity on white soft wheat flour at 20, 25, 30 and 32.5 °C. The net reproductive rate increased from 0.08 females/female at 20 °C to 11.77 females/female at 25 °C and 102.07 females/female at 30 °C, followed by a decrease to 10.73 females/female at 32.5 °C. The lowest values of the intrinsic rate of increase and the finite rate of increase were observed at 20 °C (- 0.0105 females/female/day and 0.9895, respectively) and the highest at 30 °C (0.0348 females/female/day and 1.0354, respectively). While the mean generation time did not differ significantly between 20 and 25 °C (249.9 and 225.5 days, respectively), this decreased to 132.8 and 115.1 days at 30 and 32.5 °C, respectively. The value of the doubling time was negative at 20 °C (- 67.5 days), increased to 19.9, 34.0 and 63.9 days at 30, 32.5 and 25 °C, respectively. Using the non-linear Briere model, the lower threshold for T. castaneum population increase was estimated to be 22.2 °C, the upper threshold at 33.2 °C, and the temperature for maximum growth rate was 30.1 °C. Survival analysis indicated that temperature also affected the mortality risk of T. castaneum. The mean survival time increased from 112.1 days at 20 °C to 462.4 days at 25 °C, followed by a decrease to 206.5 and 64.5 days at 30 and 32.5 °C, respectively. We expect these results to be useful for the prediction of the population growth, the potential expansion and consequently management of T. castaneum.

Effects of defect action level of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) fragments on quality of wheat flour.

BACKGROUND: Tribolium castaneum (Herbst) is one of the most important secondary storage pests of all types of flour and flour-based products. The present study focuses on the fragment producing behaviour of T. castaneum in wheat flour during storage and its effect on the quality parameters and defect action level (DAL) of fragments. The US Food and Drug Administration has set a DAL of 75 insect fragments in 50 g of flour. Box-Behnken design was used to optimize the storage conditions (storage period in days and temperature in degrees Celsius) and insect density (numbers) to keep insect fragments below the DAL. RESULTS: Optimization results indicated that the presence of single number of adult of T. castaneum is enough to cross the DAL of insect fragments within a storage period of 21 days at a storage temperature of 30 °C. Insect fragments cause perceptible changes in the quality of wheat flour. When sample attained DAL of T. castaneum fragments in wheat flour,the various quality parameters were analysed in that moisture content of wheat flour was 10.8 ± 0.26%, total colour change was 2.052 (ΔE value), T. castaneum progeny emergence was 19.66 ± 1, uric acid was 1.8 ± 0.16 g kg-1 and microbial count was 7.34 ± 0.5 cfu g-1 . CONCLUSIONS: Results from the present study indicate that the presence of even a single adult of stored pest in wheat flour should not be ignored. It is mandatory to determine the threshold level and frequent sampling is required to achieve zero tolerance of stored product insects in food commodities. © 2021 Society of Chemical Industry.

The red flour beetle Tribolium castaneum: A model for host-microbiome interactions.

A large body of ongoing research focuses on understanding the mechanisms and processes underlying host-microbiome interactions, and predicting their ecological and evolutionary outcomes. To draw general conclusions about such interactions and understand how they are established, we must synthesize information from a diverse set of species. We analysed the microbiome of an important insect model-the red flour beetle Tribolium castaneum-which is a widespread generalist pest of stored cereals. The beetles complete their entire life cycle in flour, which thus serves multiple functions: habitat, food, and a source of microbes. We determined key factors that shape the T. castaneum microbiome, established protocols to manipulate it, and tested its consequences for host fitness. We show that the T. castaneum microbiome is derived from flour-acquired microbes, and varies as a function of (flour) resource and beetle density. Beetles gain multiple fitness benefits from their microbiome, such as higher fecundity, egg survival, and lifespan; and reduced cannibalism. In contrast, the microbiome has a limited effect on development rate, and does not enhance pathogen resistance. Importantly, the benefits are derived only from microbes in the ancestral resource (wheat flour), and not from novel resources such as finger millet, sorghum, and corn. Notably, the microbiome is not essential for beetle survival and development under any of the tested conditions. Thus, the red flour beetle is a tractable model system to understand the ecology, evolution and mechanisms of host-microbiome interactions, while closely mimicking the host species' natural niche.

Tyrophagus putrescentiae group 4 allergen allergenicity and epitope prediction.

INTRODUCTION AND OBJECTIVES: Allergen-specific immunotherapy (ASIT) is the only allergic disease-modifying therapy available for children and adults, and recombinant allergens are an interesting approach to improve allergy diagnosis and ASIT. Tyrophagus putrescentiae is a common storage mite that produces potent allergens. The aim of this study was to express and characterize recombinant group 4 allergen protein of T. putrescentiae (Tyr p 4), and to further investigate allergenicity and potential epitopes of Tyr p 4. MATERIALS AND METHODS: The cDNA encoding Tyr p 4 was generated by RT-PCR and subcloned into pET-28a(+) plasmid. The plasmid was then transformed into E. coli cells for expression. After purification by nickel affinity chromatography and identification by SDS-PAGE, recombinant Tyr p 4 protein was used for a skin prick test and an ELISA to determine the allergic response. RESULTS: Study participants' allergic response rate to Tyr p 4 protein was 13.3% (16/120). Eight B-cell epitopes and three T-cell epitopes of Tyr p 4 were predicted. CONCLUSIONS: Similar to group 4 allergens of other species of mite, allergenicity of Tyr p 4 is weak. The expression, characterization and epitope prediction of recombinant Tyr p 4 protein provide a foundation for further study of this allergen in the diagnosis and ASIT of storage mite allergy.

Oral mite anaphylaxis: who, when, and how?

PURPOSE OF REVIEW: To present an update on the recent advances in the understanding of the mechanisms and practical management of oral mite anaphylaxis (OMA, pancake syndrome). RECENT FINDINGS: Among novel observations regarding OMA, this review highlights the increased prevalence of aspirin/NSAID hypersensitivity inpatients affected by OMA, the association of OMA with exercise-induced anaphylaxis, the presentation of OMA simulating acute asthma, the occurrence of OMA in childhood, the high severity and lethal potential of OMA, the contamination of other foods, such as oat and corn flour with mites, and the simultaneous induction of OMA symptoms in more than one individual exposed to the same food source. SUMMARY: OMA is a severe, potentially lethal, acute allergic condition that should be suspected whenever symptoms begin soon after the intake of mite-contaminated foods. Physician awareness on this clinical picture is of paramount importance to establish a correct diagnosis and to implement adequate preventive measures to help patients at risk to avoid its occurrence.

Conservation of stored food using plant's extracts. Effect of oregano (Origanum vulgaris) essential oils on the reproduction and development of flour moth (Ephestia kuehniella).

In the search for effective methods of biological control of stored products insect-pests, the essential oil of Origanum vulgaris was extracted using Clevenger apparatus and tested on reproduction and mortality of flour moth Ephestia kuehniella. Bio-insecticide works with a double action mechanism; administered by inhalation in pupae, essential oil affects their pupal development. It also disrupts the reproduction of exuviated adults by extending the preoviposition period and reducing the period of egg laying and fecundity because fecundated females cannot live more than four days compared to control group. Moreover, the essential oil administered by inhalation in adults causes a significant mortality rate compared to control group by reducing their lifespan. A repellent effect against larvae and adults of this pest was noticed in this work. This allowed us ranking this oil as "moderately repulsive".

Development of a peptide substrate for detection of sunn pest damage in wheat flour.

BACKGROUND: Since the common protease substrates did not give satisfactory results for the determination of Sunn pest protease activity in damaged wheat, different peptide substrates derived from the repeated sequences of high molecular weight glutenin subunits were synthesized. RESULTS: Hydrolysis of peptides by pest protease was determined by high-performance liquid chromatography. Among three peptides having the same consensus motifs, peptide1 (PGQGQQGYYPTSPQQ) showed the best catalytic efficiency. A novel assay was described for monitoring the enzymatic activity of protease extracted from damaged wheat flour. The selected peptide was labeled with a fluorophore (EDANS) and quencher (Dabcyl) to display fluorescence resonance energy transfer. The proteolytic activity was measured by the change in fluorescence intensity that occurred when the protease cleaved the peptide substrate. Furthermore, the assay developed was modified for rapid and easy detection of bug damage in flour. Flour samples were suspended in water and mixed with fluorescence peptide substrate. After centrifugation, the fluorescence intensities of the supernatants, which are proportional to the protease content of the flour, were determined. CONCLUSION: The total analysis time for the assay developed is estimated as 15 min. The assay developed permits a significant decrease in time and labor, offering sensitive detection of Sunn pest damage in wheat flour. © 2018 Society of Chemical Industry.

The Investigation of the Presence of Mites in Some Served Dry Foodstuffs.

OBJECTIVE: Mites are microscopic organisms that lower the quality of life of people who are sensitive to them by causing conditions such as atopic dermatitis, allergic rhinitis, and asthma. These organisms are found in every habitat where humans live. This study was conducted to determine the presence of storage mites in dry food items. METHODS: Various food items were procured 10 times each in 300-gram samples. Mites were extracted with a Berlese funnel apparatus over Erlenmeyer flasks containing 70% alcohol placed at the end of the funnel stems for over 48 h. RESULTS: Of 25 food items examined in the study, only six were contaminated by mites. Species of the mites found were Acarus siro (34.6%), Glycyphagus domesticus (22.8%), Tyrophagus putrescentiae (16.8%), Tyrophagus spp. (7.9%), Rhizoglyphus spp. (1%), Lepidoglyphus destructor (7.9%), Cheylettus malacensis (4%), and Cheylettus spp. (2%). CONCLUSION: Although the results of the study show that the presence of mites in food items sold in open containers at open-air markets or stores was low, we suppose that they can cause important health problems for sensitive people.

Transcriptome sequencing reveals maelstrom as a novel target gene of the terminal system in the red flour beetle Tribolium castaneum.

Terminal regions of the Drosophila embryo are patterned by the localized activation of the Torso-RTK pathway, which promotes the downregulation of Capicua. In the short-germ beetle Tribolium, the function of the terminal system appears to be rather different, as the pathway promotes axis elongation and, in addition, is required for patterning the extra-embryonic serosa at the anterior. Here, we show that Torso signalling also induces gene expression by relieving Capicua-mediated repression in Tribolium Given that the majority of Torso target genes remain to be identified, we established a differential gene-expression screen. A subset of 50 putative terminal target genes was screened for functions in early embryonic patterning. Of those, 13 genes show early terminal expression domains and also phenotypes were related to terminal patterning. Among others, we found the PIWI-interacting RNA factor Maelstrom to be crucial for early embryonic polarization. Tc-mael is required for proper serosal size regulation and head morphogenesis. Moreover, Tc-mael promotes growth-zone formation and axis elongation. Our results suggest that posterior patterning by Torso may be realized through Maelstrom-dependent activation of posterior Wnt domains.

[Gohieria fuscus breeding heavily in grand dust flour of a flourmill].

Objective To investigate the breeding quantity and average breeding density of Gohieria fuscus in the grand dust flour of a flourmill and explore the prevention and control measures. Methods A certain amount of grand dust flour was collected from a flourmill, and it was sieved. The powder was placed into the glass pan, and the mites were sought out under an optical microscope and made of specimens. The mites were identified on the basis of literature. Results In this survey, 400 g samples were collected from 4 habitats. The average breeding density of mites was 3 516/g. The mite was identified as Gohieria fuscus. ConclusionsGohieria fuscus is one of the widely distributed stored mites. It impacts the stored food and reduces the quality of food. In addition, the mite affects human health. Therefore, the preventive measures should be taken.

[Blomia tropicalis is found in a flour warehouse of a food factory in a civil aviation airport].

Objective To investigate whether there is Blomia tropicalis breeding in the flour warehouse of food factory in a civil aviation airport, and, if there is, to observe the morphological structure of the mite. Methods The flour samples were collected from the flour warehouse of food factory in a civil aviation airport. The breeding mites were isolated from the samples by direct microscopy and made into specimens to observe with a light microscope. Results Female Blomia tropicalis was found in the collected flour samples. Under the microscope, the mite was nearly spherical, and it had no tergum and claw. Its apodemeⅠ was developed and connected in the midline. The reproductive hole was located between the foot Ⅲ and IV level and was covered with a pair of oblique genital folds. The foot Ⅲ and Ⅳ had no solenoids. The copulatory pouch was a long, slightly curved tube, extending from the end of the mite. ConclusionsBlomia tropicalis has been found in the flour warehouse of a food factory in the civil aviation airport. The main distinguishing feature of this mite is that it has no tergum, its feet have no pectinate inferior tarsus scales or claw, the feetⅠgenu has only one solenidia, and feet Ⅲ and Ⅳ have no solenidias.

[Investigation and morphological observation of Suidasia breeding in flourmills in Huaibei].

OBJECTIVE: To investigate the Suidasia breeding in the flourmill and further observe its morphological characteristics. METHODS: The samples were collected from different habitats of a flourmill and then separated, and the chipping was kept. The mites were selected and counted from the chipping under an optical microscope. The mites were made slide samples and identified. RESULTS: The mites were identified as Suidasia (including Suidasia nesbitti and Suidasia medanensis). A total of 20 samples were collected in this study, of which 13 were positively detected, with the detection rate of 65%. There were 2 876 mites of Suidasia that were detected from 200 g sample. The average breeding density was 14.38/g. CONCLUSIONS: It is common that Suidasia breeding in flour, which might cause human acariasis and allergic asthma. Therefore, the effective prevention measures should be taken.

[Study on natural population dynamics and spatial distribution pattern of Tyrophagus putrescentiae in stored flour].

OBJECTIVE: To understand the natural population dynamics and spatial distribution of Tyrophagus putrescentiae in storage flour, so as to provide an evidence for its prevention and control. METHODS: The samples from five sampling points in Wuhu City were collected monthly from January to December, 2013, and examined and counted for T. putrescentiae. The dispersion pattern target, Iwao's m*- x̄; regression analysis and Taylor's lgS2-lg x̄; regression analysis were used for analyzing the spatial distribution pattern of T. putrescentiae in the storage flour. RESULTS: The peaks of population dynamics of T. putrescentiae were discovered in July and September. The indexes of dispersion were as follows：I > 0, CA > 0, m*/ x̄; > 1; and the linear regression equation of Iwao：m* = 3.740 3 + 1.017 5 x̄; (r = 0.995 8) and Taylor：lgS2 = 0.500 4 + 1.134 9 lg x̄; (r =0.832 8) showed that the spatial distribution pattern of T. putrescentiae in the storage flour was assembled. CONCLUSIONS: The peak of population dynamics of T. putrescentiae in the storage flour in Wuhu City is a double peak type, and the spatial distribution pattern of T. putrescentiae is assembled.

[Preliminary investigation of Suidasia nesbitti breeding status in ground dust flour in Qiqihaer City].

OBJECTIVE: To investigate the Suidasia nesbitti breeding status in the ground dust flour collected in Qiqihaer City. METHODS: Totally, 16 aliquots of ground dust flour were respectively collected from a college canteen and 15 households in Qiqihaer City. Then 10 g dust flour was taken from individual sample for isolation of the mites that were made of slide specimen, and the mites were identified and classified under a microscope. RESULTS: Acaroid mites were found in 15 of the 16 aliquots of samples (detection rate being 93.8％), and 7 species, belonging to 6 genera under 3 families, were identified. A total of 561 heads of mites were isolated from 160 g samples, with an average breeding density of 3.51 heads/g. The most breeding mite was associated with S. nesbitti. CONCLUSIONS: Various species of mites are breeding in the ground dust flour in Qiqihaer City, and S. nesbitti occurs the most. These findings indicate that effective measures should be taken to prevent and control the harm associated with acaroid mite contamination.

[Population dynamics and spatial distribution pattern of Aleuroglyphus ovatus].

OBJECTIVE: To characterize the population dynamics and spatial distribution of Aleuroglyphus ovatus in the flour warehouse, so as to provide the basic evidence for improving the sampling guidelines that are essential for effective pest monitoring and management. METHODS: The samples from flour warehouses of four localities were collected, examined and counted for A. ovatus in every month in Wuhu City. The dispersion pattern target, Iwao m*/x̅ regression analysis and Taylor power method were used for analyzing the spatial distribution pattern of A. ovatus in the flour warehouses. RESULTS: The peaks of population dynamics of A. ovatus were discovered in July and September, respectively. The indexes of dispersion were as follows：I > 0, CA > 0, m*/x̅ > 1. At the same time, the parameters in the equation of Iwao：m*=5.471+1.022 x̅ (r = 0.999) and Taylor： lgS2 = 0.697+1.111 lg x̅ (r = 0.987) showed that the spatial distribution pattern of A. ovatus was assembled. CONCLUSIONS: The peaks of population dynamics of A. ovatus in the flour warehouse are bimodal pattern, and the spatial distribution pattern of A. ovatus is assembled.

Effects of Flour and Milling Debris on Efficacy of Beta-Cyfluthrin for Control of Tribolium castaneum (Coleoptera: Tenebrionidae).

Laboratory and field studies were conducted to determine if accumulation of a flour food source or milling debris affected residual efficacy of beta-cyfluthrin for control of Tribolium castaneum (Herbst), the red flour beetle. In the laboratory study, the high label rate of 20 mg active ingredient (AI)/m2 gave effective control for 8 wks, regardless of whether or not the concrete was sealed prior to application or the presence of flour contamination. However, with the low label rate of 10 mg AI/m2, the flour apparently absorbed the insecticide residues from the treated surface, and sealing the concrete did not have a beneficial effect on efficacy. Two field studies with the low label rate were conducted during autumn of 2012 and 2013 and summer of 2013, using only unsealed concrete. Accumulated milling debris caused a reduction in efficacy in the autumn studies, as shown by increased time to 100% knockdown, decreased mortality, and decreased residual efficacy. There was no such corresponding decrease in residual efficacy in the summer study. Overall, results of both studies show that accumulated food and milling debris can absorb residue of beta-cyfluthrin from a treated surface and have a negative impact on residual efficacy, particularly with the low label rate of 10 mg AI/m2.

Dust mite infestation in cooking flour: experimental observations and practical recommendations.

BACKGROUND: The first documented case of oral mite anaphylaxis has recently been reported in Thailand, with mites possibly originating from cooking flour. OBJECTIVE: Our study was designed to assess the effects of cooking flours enhancement and storage conditions on mite proliferation and to provide practical recommendations to prevent mite anaphylaxis. METHODS: In a factorial experiment, six commercial brands of cooking flours were selected and either inoculated or set free of mites and stored in one of the four containers chosen for the study: original package, plastic bag, plastic box and glass bottle. The resulting experimental units where then stored at either room temperature or in a refrigerator (+4C). In order to determine levels of Der f 1 allergen, 0.1 gram of flour was sampled from each experimental unit and tested by ELISA. Sampling was carried out immediately after inoculation and subsequently at week 2, 4, 6, 8, 10, 12, 16 and 20. RESULTS: Levels of Der f 1 allergen in the inoculated samples increased significantly in all conditions 6 weeks after inoculation (p <0.001) and reached the highest levels at week 8. While experimental units left at room temperature showed higher levels of mite growth (p <0.001), no statistical differences were found among types of containers. The highest amount of Der f 1 was observed for Gogi, followed by Gold Label, tempura flour, corn flour, wheat flour and tapioca starch, respectively (p <0.01). CONCLUSIONS: In the context of our experiment, mites preferably grew in cooking flours containing high amounts of wheat at room temperature, particularly after 8 week of storage. According to our results, we thus advise to keep household cooking flour refrigerated and while the type of container does not matter, storage should not exceed 20 weeks.

[Survey and morphological observation of Lepidoglyphus destructor in college canteens].

OBJECTIVE: To understand the breeding and morphology of Lepidoglyphus destructor in college canteens in south Anhui Province. METHODS: The powder and rice on the floor around dough makers, flour bags and rice bags in college canteens were collected and observed under a microscope. RESULTS: Totally 108 samples were collected, and Acaroid mites were found in 101 of them with a detection rate of 93.52%. Totally 1 527 mites were found with an average breeding density of 1.41/g. Under the light microscope observed, the L. destructor's four pairs of legs were tapering from tarsus. The back setae were stiff and the ventral setae were smooth and relatively short. The internal vertical seta was longer than the top of the chelicera. Dorsal seta d3, d4, lateral seta l3 and sacral inner hair sai were the longest. The female mites were bigger than the male ones, and had more anal seta than male ones. The genital fold of female mites almost connected together, and the front-end had a crescent shaped plate cover. CONCLUSIONS: The breeding of Acaroid mites in college canteens is serious, and therefore, effective measures should be taken to prevent and control it.