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Characterization of volatile organic compounds released by granivorous insects in stored wheat
... Many factors might affect the optimization of extraction conditions which include an optimum extraction time and the correct fibre for capturing the whole range of VOCs, the temperature during extraction and the fibre absorption time from the headspace [25]. Identification of the volatile organic compounds emitted by grain insects in future can be used in early detection of insects in stored grains using headspace analysis [15,24]. Based on previous studies, the aim of this study is to focus on developing optimal condition to collect volatile organic compounds from Trogoderma variabile including a number of insect and extraction time, followed by identification of unique peaks which can be used as early infestation detection tool for Trogoderma variabile. ...
... Different number of insects (15,20,25, and 30) were tested for each life stage to get the optimal number of insects. larvae (mixed instars) and adults (mixed male and female) were placed into 5 ml glass vial (SUPLICO, USA Lot: 82742) and kept in 35°C in thermostatic and humidity chamber (HWS, Ningbo southeast Dongnan Instrumental Ltd) for four hours to enhance the release of VOCs. ...
... Extraction time is a significant parameter in hand space solid phase microextraction. It is an important step to determine extraction time using SPME fibre method [15,30]. The amount of extracted volatile depends on the sampling method such as extraction time [20,31]. ...
Volatile organic compounds (VOC) emitted by Trogoderma variabile at different life stages (larvae, female and male) can help us to understand the chemical signals that are released by the beetle which can serve as biomarkers for diagnostic purpose. There are several factors that effect on the optimization of VOC extraction including, temperature, jar size, number of insects, duration of extraction, and gas chromatography (GC) conditions. This study used headspace solid phase microextraction (HS-SPME) fibre coupled with flame ionization detection (FID) and gas chromatography with mass spectrometry (GC-MS) to determine the optimal method for accurate, rapid and cost-effective extraction and identification of VOC from different life stages of T. variabile. The HS-SPME technique and the analytical conditions with GC and GCMS were optimized and validated for the determination of VOCs released from T. variabile. Selection of the number of insects was based on the height and the number of peaks. Results showed that 15 and 20 larvae and adults respectively gave the best number of peaks. Sixteen hours were optimized as the best extraction time for larvae and adults to get maximum number of emitted VOCs. The number of compound released from T.variabile different stages was 7, 9 and 11 for male, female and larvae respectively. Furthermore, some compounds were identified in all stages such as oxime-, methoxy-phenyl, 2(3H)-furanone, 5-ethyldihydro- and nonanal. Also, most of the compounds were significantly different in peak area between different life stages.
... The headspace analysis techniques have been widely used in food and flavor industries for the quality assessment of food products. They also play a role in determining ongoing spoilage of foods and characterizing volatiles specific to stored pest products [20]. The headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography (GC)-mass spectrometry (MS) techniques are a useful and convenient method to extract and examine pheromones and other volatile secretions of coleopteran insects [21][22][23]. ...
... The headspace volatiles from live S. granarius adults in sealed flasks at different densities (1,5,10,20,50 and 100 individuals per flask) were collected using an HS-SPME technique and analyzed by GC-MS in order to investigate chemicals released by the adult weevils, which may be the chemical signals involved in the chemical communication. Several main volatile components in the headspace of S. granarius adults were identified with the potential bio-functions of two main components, 3-hydroxy-2-butanone and 1-pentadecene, on the behavior of this species and were explored with EAG and behavior bioassay techniques. ...
Simple Summary
Postharvest loss has become a crucial issue for the grain supply chain. Storage of grain without losses in quality is a critically important aspect of global food security. The monitoring and detection of insect infestations in stored grain is essential to inform pest management decisions. Insect olfaction is a principal sensory modality for sensing semiochemicals from their external environment and regulates their behaviors. Some semiochemicals function as attractants or repellents, which could be used for insect surveillance and pest control. In this study, the granary weevil Sitophilus granarius (L.), was used as an example to evaluate volatile compounds released from the weevils’ and their initiated electrophysiological and behavioral responses. An improved understanding of S. granarius chemical ecology will lead to developing more efficient and environmentally friendly pest control strategies and technologies.
Abstract
The granary weevil Sitophilus granarius (L.) is one of the most serious primary insect pests of stored products. When S. granarius present in grains, various volatile organic compounds are released as chemical signals which can be used to detect the insects. In this study, volatile chemical compounds released from S. granarius were analyzed using the headspace solid phase micro-extraction (HS-SPME) coupled with gas chromatography (GC)–mass spectrometry (MS) techniques. Two key compounds, 3-hydroxy-2-butanone and 1-pentadecene, were identified from mixed gender of S. granarius adults at high density. Moreover, both male and female adults showed dose-dependent electroantennography (EAG) responses to 3-hydroxy-2-butanone. In behavioral assays, S. granarius was attracted to 3-hydroxy-2-butanone at 0.001 µg/10 µL but repelled at 10 µg/10 µL or higher. S. granarius was consistently repelled by 1-pentadecene at concentrations at 0.001 and 1000 µg/10 µL. 3-hydroxy-2-butanone and 1-pentadecene have considerable potential to offer in the development of new approaches for the monitoring and management of this destructive stored grain insect pest.
... A variogram was prepared at each introduced insect density [12]. To test if the previous insect densities would influence the distribution of the following introduced insects, Spearman's coefficient of rank correlation was determined [8], the correlation coefficient was calculated and its significance was tested [31]. A frequency table was prepared by ranking the collected insect numbers in each sample unit into ten groups. ...
... The Chi-square test and Lagrange multiplier statistics for type three analyses, were applied at a = 0.05 level. We treated the ten groups as ordinal data [1,2] and Proc GENMOD in SAS 9.2 [31] was used to conduct the normal and Poisson distribution tests. The negative binomial and binomial distribution were tested using the numbers of sample units with zero adult count and non zero count in sample units at the same temperature or same introduced insect density. ...
Three dimensional temporal and spatial distributions of adults of Tribolium castaneum (Herbst) at insect densities of 0.1 (low), 1.0 (medium), and 5.0 (high) adults/kg wheat (A/kg) were determined in a 1.5 t bin of wheat with 11 ± 0.8%, 13 ± 0.6% and 15 ± 0.3% moisture contents (wet basis) at 20 ± 1, 25 ± 1 and 30 ± 1°C. The 1.5 t of wheat was sampled at five locations. At each location, grain was separated into three 15 kg vertical layers and adult numbers in each layer were counted. Adults did not prefer any location in the horizontal direction, while fewer adults were recovered from the bottom layers than that from the top and middle layers. Number of adults at a location with any temperature or insect density did not correlate with its adjacent locations in either vertical or horizontal direction. The temporal continuous property existed at all insect densities. These results were consistent with the tendency of the aggregation of the adults at the low and medium densities. Adults had highly clump distributions at low and medium densities and this aggregation behavior decreased with the increase of insect densities. Temperature tested did not influence their aggregation behavior.
... In humans, VOC surveillance is an established field for detecting respiratory, urinary tract and gastrointestinal infections (Sethi et al., 2013), and was utilized for SARS CoV-2 surveillance during the 2021 pandemic (Sharma et al., 2023). VOC surveillance has been extensively studied for detecting the insects themselves, especially those assessed to be pests, for example, wood borer beetles (Semanotus bifasciatus and Phloeosinus auebi) (Wang et al., 2020), stink bugs (Chinavia hilaris and Nezara viridula) (Henderson et al., 2010), flour and grain beetles (Tribolium castaneum and Cryptolestes ferrugineus, respectively) (Senthilkumar et al., 2012) and bark beetles (Scolytinae spp.) (Amin et al., 2013;Berg et al., 2013;Paczkowski et al., 2021). To the best of our knowledge, the only insect system that VOC disease surveillance has been applied to is apiculture. ...
Insects play crucial roles in nearly every ecosystem and provide a wide array of ecosystem services. However, both managed and wild insect populations face threats from parasites and pathogens, which require surveillance to mitigate.
Current infectious disease surveillance methods for insects often involve invasive, time‐consuming and occasionally destructive techniques, such as manual inspections and molecular detection.
Volatile organic compound (VOC) surveillance provides a real‐time, accurate and non‐invasive alternative for disease detection and has been well‐established in humans and livestock.
Recent advances in sensor technology now allow for the development of in‐field VOC surveillance devices. This review explores the need for disease surveillance in insects and highlights recent advances of using VOCs for this purpose, focusing on honey bees as an example.
We outline potential applications, challenges and future prospects of using VOCs for insect disease surveillance, providing examples of how this technology could be globally applied to mitigate the impacts of disease in a range of insect systems.
... Gas chromatography-mass spectrometry (GC-MS) has been used by researchers to analyze T. castaneum's volatile odor [16,17]. Based on previous studies and the results of GC-MS analysis of pests and wheat, 10 metal oxide gas sensors were first chosen for the analysis findings that include more volatile components such benzoquinones, phenols, and olefins. ...
Pest infestation during grain storage reduces the weight and quality of the grain, which poses a risk to food safety. It’s important to have a reliable, quick, and intelligent approach for spotting pests in grain storage. In this study, an electronic nose (e-nose) was designed to detect the different densities of Tribolium castaneum (Herbst) in stored wheat. To avoid the phenomenon of “dimensional disaster” caused by the large amount of data in the e-nose data processing, the eigenvalues of the e-nose response curve were extracted to form the original feature matrix for data analysis. Then, to obtain the optimal feature matrix, the initial feature matrix was gradually refined using multivariate statistical methods such as response strength analysis, analysis of variance, coefficient of variation analysis, and correlation analysis. Finally, the feature matrix was regressed using partial least squares regression (PLSR), principal component regression (PCR), support vector machine regression (SVR), and Gaussian process regression (GPR) to establish various prediction models. The GPR model presented the best prediction effect among the four regression models, and its correlation coefficient (R), root mean square error (RMSE), and relative analysis error (RPD) were 0.96, 9.08, and 2.24, respectively. This work provides a feasible optimization method by which the e-nose can be used to detect stored grain pest density within a very small error margin and promotes the development of intelligent agriculture.
... Larval and adult insects secreted distinct volatiles useful for early monitoring of infestation. Senthilkumar et al., (2012) Detected T. castaneum and C. ferrugineus by headspace analysis (HS-SPME) coupled with GCMS. Niu et al., (2016) Used SPME coupled with GC-FID and GC-MS to establish relationships between storage period and grain quality, and grain quality and insect infestation of R. dominica in wheat. ...
Smart detection and scientific disinfestation technologies play a crucial role in ensuring the safety and quality of food grains, protecting them from pests, pathogens, and contaminants. These technologies leverage advancements in science and technology to enhance the efficiency, accuracy, and sustainability of food grain protection, benefiting farmers, consumers, and the environment. One of the key challenges in food grain protection is the early detection of pests and pathogens. Smart detection technologies utilize sensors, like optical, acoustic and thermal, to detect signs of infestation or contamination in food grains. By detecting these issues early, farmers can take timely action to prevent further damage and ensure the quality of their harvest. Smart detection technology like electronic noses to detect odors emitted by pests or pathogens in food grains, acoustically to detect the feeding of insects as internal borers, hyperspectral imaging uses advanced imaging techniques to detect subtle changes in the color and texture of food grains, variation in temperature profiling of the infested and uninfested grains are all getting known slowly. Likewise, scientific disinfestation technologies are used to eliminate pests from food grains without compromising their quality. Technologies like physical methods (heat treatment and irradiation), as well as chemical methods (fumigation) can reduce pest load thus gives quality food. Overall, these technologies are essential for protecting food grains from pests, pathogens, and contaminants. By leveraging these technologies, farmers can ensure the safety and quality of their harvests, reduce the use of chemical pesticides, and protect the environment and human health.
... Unlike plants, insects contain very few volatile organic compounds that are affected by heat. Senthilkumar et al. (2012) reported several volatile organic compounds released by two species of adult beetles, Tribolium castaneum (Coleoptera: Tenebrionidae) and Cryptolestes ferrugineus (Coleoptera: Laemophloeidae), including methyl-1,4-benzoquinone, ethyl-1,4-benzoquinone, and 1-tridecene. These compounds are mainly pheromones of beetles. ...
... Benzoquinones are produced by the adults of T. castaneum and their amount varies with insect densities, increasing with the number of individuals, and also with time but in a nonlinear way [23,24]. High levels of benzoquinones can be associated with strong densities of T. castaneum to act as a repellent to larvae and adults [23,25,26] or because the production of the aggregation pheromone decreases during adulthood [26]. ...
Simple Summary
The environmental conditions selected to store food products can be favorable to the development of different biotic degradation agents, such as insects and fungi. The interactions between these two groups of organisms may be multiple, and not restricted to antagonistic relationships. Competition may arise between stored products associated fungi, and insects, as they often thrive for the same food sources. Adults of Tribolium castaneum insects, a major stored food-product pest worldwide, produce benzoquinones, which are released as chemical defenses against other organisms. This study evaluated the effect of these substances on the development of six maize-associated fungal species: Aspergillus flavus, A. fumigatus, A. niger, Fusarium sp., Penicillium sp., and Trichoderma sp. The results obtained showed that all the fungi tested are susceptible to the benzoquinones produced by T. castaneum, but the level of sensivity is species specific, with most of the fungi showing a delayed growth. The contact of Penicillium sp. with a mixture of two benzoquinones, produced by T. castaneum, was deadly. Revealing the nature of the relationship between some fungal species and adults of T. castaneum can be a step forward for a better management in the preservation of stored food products.
Abstract
Tribolium castaneum (Herbst) adults produce 1,4-benzoquinone (BQ), methyl-1,4-benzoquinone (MBQ), and ethyl-1,4-benzoquinone (EBQ). These components are chemical defenses used as repellents and irritants, and BQ has a negative impact on the growth of some fungal species. In this work, the inhibitory and/or lethal effects of these benzoquinones on the development of six fungi identified in maize, namely Aspergillus flavus, A. fumigatus, A. niger, Fusarium sp., Penicillium sp., and Trichoderma sp., were evaluated. Ten-day-long disk diffusion trials were performed using benzoquinones. The experiments simulated the activity of BQ (B1) or “EBQ + MBQ” (B2) released by 40-day-old insect adults (n = 200), considering a total average release of 45 µg per adult. Inhibition halos imposed by benzoquinones on fungal growth showed a significant effect when compared with the controls (water and solvent). Mycelial growth was decreased for all fungi, with the level of response depending on the fungal species. B1 and B2 displayed an inhibitory effect against all fungi, but Trichoderma sp. and A. niger showed rapid recoveries. B2 showed a lethal effect on Penicillium sp. The inhibitory and lethal activities of benzoquinones released by T. castaneum adults may contribute to regulate fungal growth, and understanding their interaction is important to develop innovative control strategies.
... As mentioned previously, Henderson et al. [56] used an electronic nose to detect the presence of stink bugs by detecting the VOCs emitted by the bugs themselves. Senthilkumar et al. [80] used GC-MS to characterize the VOCs emitted by Tribolium castaneum and Cryptolestes ferrugineus. Xu et al. [30] used the PEN3 electronic nose to determine the age and amount of brown rice plant hoppers by sensing the VOCs emitted by the bugs themselves. ...
Each year, unwanted plant pests and diseases, such as Hendel or potato soft rot, cause damage to crops and ecosystems all over the world. To continue to feed the growing population and protect the global ecosystems, the surveillance and management of the spread of these pests and diseases are crucial. Traditional methods of detection are often expensive, bulky and require expertise and training. Therefore, inexpensive, portable, and user-friendly methods are required. These include the use of different gas-sensing technologies to exploit volatile organic compounds released by plants under stress. These methods often meet these requirements, although they come with their own set of advantages and disadvantages, including the sheer number of variables that affect the profile of volatile organic compounds released, such as sensitivity to environmental factors and availability of soil nutrients or water, and sensor drift. Furthermore, most of these methods lack research on their use under field conditions. More research is needed to overcome these disadvantages and further understand the feasibility of the use of these methods under field conditions. This paper focuses on applications of different gas-sensing technologies from over the past decade to detect plant pests and diseases more efficiently.
... But E-nose failed to discriminate between wheat flours with different pest densities; thus it cannot perform a quantitative analysis. Dimethyl benzoquinone released by the adult is a defensive pheromone, also used to detect T. castaneum (Senthilkumar et al. 2012). Therefore, we can try to use the E-nose to detect the strength of specific components in infected wheat flour, and then accurately quantify the density of T. castaneum. ...
As wheat flour is a raw material for many food products, its cleanliness has a great impact on the safety of flour-derived products. The red flour beetle known as Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) is a major pest of wheat flour. Insects’ invasion in wheat flour increases the pollutants, which may result in the reduction of edibility and safety as well as substantial economic losses. Therefore, this review aimed to elucidate the recent research regarding the reproduction, detection, and disinfestation of T. castaneum in wheat flour. Environmental factors and wheat flour varieties directly affect the reproduction of T. castaneum. In terms of detection methods, the uric acid method, near-infrared spectroscopy, and molecular biology detection have shown promising results. To control T. castaneum, physical processes such as the impact insecticidal machine, temperature control, and diatomaceous earth were introduced. For industrial applications, impact insecticidal machines may become the most common control method in the future.
... In contrast, [26] . Showed that there is no detection secretion of the quinines in S.granarius infestation in flour and wheat grain but [27] detection secretion of the quinines in S.granarius infestation in flour and wheat grain. [28] Stated that there is increase in volatiles produced by T. castaneum adults in wheat flour samples with increasing insect density. ...
The current study was carried out to detect the secretion of benzoquinones accumulation in wheat caused by Rhyzopertha dominica. The effect of different population densities and storage periods on weight loss of wheat and the secretion of benzoquinones accumulation in wheat caused by R.dominica were investigated. The benzoquinones secreted by R. dominica adults was the first record in this paper. The results showed that loss of wheat grains significantly increased with increasing storage periods and different insect densities. The results showed there is only Ethyl 1, 4-benzoquinone was the toxic compound detected in all insect densities and storage periods. We can confirm that the organic compound ethyl 1, 4 benzoquinone was coming from R. dominica defensive secretions.
... 8, 17 1-pentadecene is a defensive secretion used to maintain distance between individuals. 15,18,19 Research has focussed on the detection of 1-pentadecene in stored products as a tool to monitor insect presence [19][20][21] but there are fewer available data on the role of 1-pentadecene for the behaviour of the insect, even though the substance is reported from a range of Tribolium species. 8 Data on the influence of 1-pentadecene on flour beetle behaviour are old and somewhat conflicting. ...
BACKGROUND
Movement of the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), in stored products is mediated by food volatiles and other semiochemicals.
RESULTS
In two‐way olfactometer assays, T. castaneum was more attracted to wheat bran previously infested with conspecifics than to uninfested bran. Chemical analysis showed that 1‐pentadecene was present in the headspace of T. castaneum‐infested wheat bran, but not detectable in the headspace of uninfested bran. An olfactometer was used to test the effect on T. castaneum behaviour of 1‐pentadecene, and of volatiles from wheat bran with and without 1‐pentadecene. The lowest concentration of 1‐pentadecene exhibited an attractive effect, compared to the control (n‐hexane). Slightly higher concentrations showed a neutral effect, while the highest concentrations repelled T. castaneum. Wheat bran with a low 1‐pentadecene concentration was more attractive than wheat bran alone, whereas higher concentrations of 1‐pentadecene were repellent.
CONCLUSION
The results provide important information on intraspecific, semiochemical‐mediated behaviour in T. castaneum, which could potentially be used to develop new methods to monitor the flour beetles in stored products. © 2021 Society of Chemical Industry.
... This amount secreted due to the cumulative number of S. granarius progeny. Senthilkumar et al., (2012) stated that there is increase in volatiles produced by T. castaneum adults in wheat flour samples with increasing insect density. The concentration of ethyl 1,4 benzoquinone released by ten T. castaneum adults were 10.6 µg/100 µl compared with 4.2 µg/100µl for five insects after 72 h storage period. ...
... There are weak air currents in bins due to temperature gradients (Gough et al. 1987). 4) The grain mass absorbs the multiple components (Senthilkumar et al. 2012) and hence, may absorb the pheromones. If there are no air currents, the pheromones absorption by grain can block the pheromone dissipation over longer distances. ...
Whether stored-grain insects can communicate with each other inside stored-grain bulks is an important question for the development of pest management programs. Movements of the individual adults of Cryptolestes ferrugineus towards caged adult(s), in the presence or absence of wheat, were studied inside an apparatus (10 cm length), using an infrared camera. The numbers of the caged adults were 1, 20, or 50 of females or males, and 100 or 200 mixed-sex adults. Without grain, both males and females moved towards the caged single male, but not the caged single female. With grain, neither males nor females moved towards the caged single male or female. When 50 males were added to the cage, females did move significantly towards the caged males. There were trends for introduced males and females to move towards caged males at higher densities.
... Grain damage caused by insect infestation during storage poses a considerable problem in agricultural production and can exceed the losses that are sustained during cultivation. Approximately 5e10% of grain is lost during storage not only due to direct damage inflicted by pests, but also due to changes in microflora and the accumulation of toxic substances (Hodges et al., 1996;Yezerski et al., 2005Yezerski et al., , 2007Senthilkumar et al., 2012). ...
The feeding behavior of storage pests colonizing the spikelets of ancient wheats remains insufficiently investigated. Therefore, the aim of this study was to determine the susceptibility of emmer, spelt and common wheat grown under different agronomic conditions to storage pests, including the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae) and the Tribolium confusum (du Val) (Coleoptera: Tenebrionidae). The experiment was performed on the spikelets of two non-free-threshing wheat species, spelt Triticum spelta (L.) cv. Wirtas and emmer Triticum diccocon (Schrank) cv. Bondka, and the grain of free-threshing common wheat Triticum aestivum (L.) cv. Bombona. The remaining experimental factors were different nitrogen fertilization rates and the application of a growth regulator. Two storage pest species, the S. granarius and the T. confusum, were introduced to the experimental grain and spikelets. The results after 6 months revealed that different nitrogen fertilization rates, the application of the growth regulator and wheat species did not affect the population size of S. granarius. After 12 months of incubation, no significant changes were found in the abundance of T. confusum in response to nitrogen fertilization, growth regulator or wheat species. After 12 months of incubation, wheat species exerted an inhibitory effect on the population size of S. granarius. Spelt was the most resistant and common wheat was the least resistant wheat species. The results of this study indicate that spelt was most resistant to storage pests, whereas common wheat grain was most abundantly colonized by storage pests.
... High temperature and long extraction time favor in the collection of more analytes (Laopongsit, Srzednicki, & Craske, 2014). Senthilkumar et al. (2012) detected the T. castaneum and C. ferrugineus by headspace analysis (HS-SPME) coupled with GCMS. Niu et al. (2016) used SPME coupled with GC-FID (gas chromatography-flame ionization detection) and GC-MS to establish relationships between storage period and grain quality, and grain quality and insect infestation of R. dominica in wheat. ...
... High temperature and long extraction time favor in the collection of more analytes (Laopongsit, Srzednicki, & Craske, 2014). Senthilkumar et al. (2012) detected the T. castaneum and C. ferrugineus by headspace analysis (HS-SPME) coupled with GCMS. Niu et al. (2016) used SPME coupled with GC-FID (gas chromatography-flame ionization detection) and GC-MS to establish relationships between storage period and grain quality, and grain quality and insect infestation of R. dominica in wheat. ...
Insects cause a major loss in stored food grains. Besides, pestilential activities of insects in stored food grains affect the marketability as well as the nutritional values. Early detection and monitoring of insects in the stored food grains become necessary for applying corrective actions. Visual inspection, probe sampling, insect trap, Berlese funnel, visual lures, pheromone devices etc., are some of the popular methods largely used in commercial granaries or grain storage establishments. Of late, electronic nose, solid phase micro-extraction, thermal imaging, acoustic detection, etc. have been reported to be successful in detecting insects. The capability of in-situ early detection, monitoring, cost, reliability, and labor requirements are the major factors considered during for selection of the method. Detection of hidden infestation, whose population may be many times higher than the free-living insects is an important concern to mitigate the losses in bulk storage warehouses, so as to enable the early actions for fumigation or to dispose off the grain. This paper reviews some of the widely used detection methods for early detection of insects’ pestilential activities in stored food grains as well as some of the novel technologies with an emphasis on acoustic method, which has a good commercial potential.
... In general, the total secretion rate of the two benzoquinones was increased with increasing of No. of pairs (insect density) of T. castaneum at the three storage periods. Senthilkumar et al. [22] found that the amount of volatiles produced by T. castaneum adults in wheat flour samples were a direct relationship which increased with an increase in insect density. The concentration of MBQ, EBQ and 1 tridecene released by ten adult insect were: 8.5, 9.1 and 10.6 µg/100 µl compared to 7, 8 and 4.2 µg/100µl for five adult insects after 72h storage period. ...
Objectives
The present study was prepared to investigate the impact of insect density, adult emergence of Tribolium castaneum on the secretion of Benzoquinones (BQs) consist of methyl-1,4-benzoquinone(MBQ) and Ethyl-1,4-Benzoquinone (EBQ), and accumulation of Aflatoxins (AFs) in wheat flour stored at different periods.
Methods
Forty grams of wheat flour were put into small glass jars (8 cm diameter and 12 cm length). Then T . castaneum was put in each jars at rates of 10, 20 and 30 unsexed pairs of insect adult. The jars were covered with muslin cloth and the rubber band was fixed to prevent insects to escape. A glass jar without any insects served as the control. The jars lifted on bench in the laboratory for two, three and four months of storage under laboratory temperature conditions (with average 28 ± 2 ⁰ C and 65±5 R.H). The previous design was replicated three times. At the end of each storage period, the jars containing the flour were sieved thoroughly by 40 wire mesh size to separate the insects. The insects have been counted on the other hand wheat flour was prepared to determine MBQ, EBQ and AFs by HPLC methods.
Results
The results indicated the levels of EBQ higher than MBQ in all infested samples at all insect densities (No. of insect pairs). The concentrations of MBQ in wheat flour released by ten adult pairs (10P) with the three storage periods two, three and four months were 10.42 ± 0.56, 22.38 ± 3.67, 27.06 ± 6.71µg/g, respectively. These results increased with insect densities to (30p) were 39.67 ± 0.10, 63.58 ± 2.35 and 106.24 ± 7.4 µg/g after storage periods two, three and four months, respectively. In addition to the concentrations of EBQ with (10P) were 67.45 ± 3.64, 98.0 ± 6.1 204.66 ± 5.8 µg/g with storage periods two, three and four months, respectively. In case (30P) the levels of EBQ were 376.7 ± 0.87, 570.1 ± 2.11 and 1558.66 ± 10.88 (µg/g). The highest concentration of the BQs 1664.90 ± 11.43 (µg/g) released by T . castaneum achieved with the highest adult emergence (1021 insect adult) and the highest insect density (30p) at four months storage period. In general, AFs levels enhanced with a period of storage and insect densities.
Conclusion
Levels of the BQs (MBQ and EBQ) increased with an increase of storage periods and insect densities. Therefore, the presence of this insect should be prevented in stored wheat flour reducing AFs contamination is possible by storage for short time and prohibit insects which causes an increase temperature of the flour and moisture, all of which promote production of AFs.
... Senthilkumar et al. [14] were the first to detect 1-tridecene from T. castaneum. They speculated that this compound was a sex pheromone of the species in accordance with a study of male Parastizopus transgariepinus (Koch) by Geiselhardt et al. [15]. ...
The objective of this study were to identify volatile organic compounds (VOCs) from flour, Tribolium castaneum (Herbst) and flour infested by T. castaneum separately, to confirm the difference of healthy flour and flour infested by T. castaneum and to explore the new technique to diagnose stored flour's quality by its VOCs change. Headspace-solid phase microextraction (HS-SPME) coupled with gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) were used to detect the VOCs of three different samples. Totally, 71 different compounds were identified in flour, T. castaneum and T. castaneum infested flour. Therefore, 27 VOCs were identified from flour alone, 32 VOCs from T. castaneum and 39 VOCs from T. castaneum infested flour. The compound 2-ethyl-2,5-cyclohexadiene-1,4-dione is only found in T. castaneum infested flour. This suggests that 2-ethyl-2,5-cyclohexadiene-1,4-dione can be a useful VOC for detecting T. castaneum in flour.
... These physical, chemical, and biological changes are used to control and monitor the quality of the stored grain (JIAN et al., 2012). Even though some volatiles produced by insects (SENTHILKUMAR et al., 2012), fungi, and grain (MYERS et al., 2012) are detected under controlled laboratory condition, it is not very clear as to which and how many chemicals are produced inside stored grain bins (Table 5). ...
Reduce contamination in feed industries is a big challenge for all the companies to get better products and to expand the consumer marketing. Thus, the aim of this study was to identify and evaluate contamination of a feed mill, suggesting a control plan based on the system of Hazard Analysis and Critical Control Points (HACCP). The experimental activities were conducted in a poultry feed facility with a capacity of 1,000 ton/day, located in Minas Gerais state, Brazil. The evaluation of the contamination was performed on flow corn, soybean meal, and feed production. After 72 hours of operation of the equipment, high levels of microbiological contaminationwere identified on the surface. The low physical quality of the products (4.2% impurities, 15.83% w.b., aw 0.85) favored the development of insects (7), fungi (1.2x107 CFU.g-1) and bacteria (1.0x107 CFU.g-1) in batches grain, and animal by-products. The high rate of contamination in raw materials enabled the formation of mycotoxins (aflatoxins of 60 ppb, 28 ppm of fumonisins) in the final products. In the steps of receiving and storage of raw materials showed the highest levels of microbiological contamination, increasing the risk of contamination of the feed end. It was concluded that the contamination physic-chemical and microbiological processing unit found in the diet adversely affect the quality of the finished feed. For quality control of products was necessary to monitor all stages of production since the arrival of the raw material until dispatch of the diets. ABSTRACT Translated: Reduce contamination in feed industries is a big challenge for all the companies to get better products and to expand the consumer marketing. Thus, the aim of this study was to identify and evaluate contamination of a feed mill, suggesting a control plan based on the system of Hazard Analysis and Critical Control Points (HACCP). The experimental activities were conducted in a poultry feed facility with a capacity of 1,000 ton/day, located in Minas Gerais state, Brazil. The evaluation of the contamination was performed on flow corn, soybean meal, and feed production. After 72 hours of operation of the equipment, high levels of microbiological contaminationwere identified on the surface. The low physical quality of the products (4.2% impurities, 15.83% w.b., aw 0.85) favored the development of insects (7), fungi (1.2x107 CFU.g-1) and bacteria (1.0x107 CFU.g-1) in batches grain, and animal by-products. The high rate of contamination in raw materials enabled the formation of mycotoxins (aflatoxins of 60 ppb, 28 ppm of fumonisins) in the final products. In the steps of receiving and storage of raw materials showed the highest levels of microbiological contamination, increasing the risk of contamination of the feed end. It was concluded that the contamination physic-chemical and microbiological processing unit found in the diet adversely affect the quality of the finished feed. For quality control of products was necessary to monitor all stages of production since the arrival of the raw material until dispatch of the diets.
... Adults of S. oryzae (3-5 d) and other species (2-3 d) were used in the experiments. Experiments were carried out in the laboratory and insect cultures were maintained at 27 ± 2 • C and 70 ± 5% r.h. ( Leelaja et al., 2007;Senthilkumar et al., 2012). ...
... These physical, chemical, and biological changes are used to control and monitor the quality of the stored grain [12,34,53,57,60]. Even though some volatiles produced by insects [67], fungi, and grain [12] are detected under controlled laboratory condition, it is not very clear as to which and how many chemicals are produced inside stored grain bins. ...
The progress in understanding the stored grain ecosystem is reviewed. Succession of insects, insect movement and distribution, interaction among insects and microflora, and the development of hot spots inside stored grain ecosystems are evaluated. Based on these case studies, we examined the understanding of the stored grain ecosystem from the view of ecosystem approach. To understand the storage grain ecosystem, integration of the parts (the collected data under small scale laboratory conditions) into a usable whole (the entire grain storage ecosystem) is required. To verify the synthesised whole, both small and full scale tests are required. To manage the stored grain ecosystem, understanding the ecosystem and application of ecosystem approach are the keys.
... For this species, but also for the other species of the genus Sitophilus, it is not clear which is the benefit from the oviposition in already-infested kernels, which consists an additional implication in the research attempts to connect ''selection'' with ''performance''. It is not clear why again, a chemical basis of host recognition is related with the existence of aggregation pheromones, in combination with food odours from ''previous insect contaminated food '' (Walgenbach et al. 1983;Athanassiou et al. 2006;Senthilkumar et al. 2012). Generally, it is considered that stored-product Curculionidae differ substantially in food-mediated oviposition selection, as compared with other species which have been used in the past to test ''selection'' and ''performance'' such as the fruit flies, Tephritidae, and the bean weevils, Bruchidae, where females usually avoid competition during egg laying (Danho and Haubruge 2003). ...
The influence of larval diet source in Sitophilus oryzae (L.), a primary grain feeder, on the choice of a new cereal host by young adult was investigated through a multiple choice comparative bioassay. For this purpose, virgin male and female adults, which had been reared as immatures in different grain commodities, were monitored according to their food preference in cylindrical arenas containing whole kernels of maize, rice, barley and wheat. The adults showed a clear individual preference for maize kernels, regardless of the previous food experience, sex and also the interval on which the adults are exposed to food. Males were much more mobile than females and visited more vigorously different commodities before the final choice. Female response was found to be related with male response to specific food sources. Hence, our results indicate that there was no natal habitat preference induction, since maize was, in most cases, the final commodity choice.
The study seeks to employ gas chromatography combined with mass spectrometry (GC-MS) to examine the chemical profile of Trogoderma variabile across different host grains, including oats, wheat, and barley. It also seeks to compare samples of healthy grain (non-insect-contaminated) to those infested by T. variabile, to determine if unique compounds can be used to detect infestation. This would suggest that HS-SPME coupled with GC-MS could serve as a method for identifying T. variabile infestations.T. variabile was reared on the three various commodities. Solid-phase microextraction (SPME) was employed, followed by gas flame ionization (GC-FID) and gas chromatography-mass spectrometry (GC-MS) for the collection, separation, and identification of compounds. The findings revealed that 23 compounds were identified from adult insects reared on canola and wheat. Additionally, 26 compounds were emitted from both non-infested and infested wheat, with 22 being highly significant. Furthermore, 21 compounds showed significant differences between non-infested and infested oats. For infested and non-infested barley, 18 compounds differed significantly between the treatments.
The rice weevil, Sitophilus oryzae (L.), is a major pest that poses a considerable threat to grain safety storage. Early detection is of great significance in reducing grain losses. Studies have demonstrated that pest infestation causes alterations in grain volatiles, potentially indicating the presence of pests. In this study, we detected volatile organic compounds (VOCs) in non-infected and pest-infected wheat on the 3rd, 9th, 17th, 22nd, and 40th days, corresponding to the developmental stages of the rice weevil at the egg, young larval, old larval, pupal, and adult stages, respectively. A total of 126 VOCs were identified, including 96 hydrocarbons, 7 alcohols, 5 aldehydes, 9 ketones, 9 esters, and 18 other compounds, 62 of which are newly produced compared to non-infected wheat. Six characteristic volatiles, namely dodecane, pentadecane, hexadecane, heptadecane, 2, 6, 10-trimethylpentadecane, and squalene, may be related to the degradation of lipids and the expression of wheat stress tolerance and underwent significant changes as infestation progressed, according to the VIP value. This study assists in interpreting the effects of rice weevil infestation on wheat at the metabolic level and establishes a foundation for storage inspection based on VOC analysis.
Analysis for extraneous matter is an important element both for selecting raw materials for food manufacturing and for monitoring the quality of processed foods. Defect action levels (DALs) of specific products are established for amounts of extraneous matter considered unavoidable and of no health hazard. However, the presence of extraneous material in a food product is unappealing, can pose a serious health hazard to the consumer, and represents lack of good manufacturing practices and sanitary conditions in production, storage, or distribution of food. This chapter provides an overview of basic official methods to isolate extraneous matter from foods, using a series of physical and chemical means to separate the extraneous material for identification and enumeration. Major concerns in the analysis of food products for extraneous matter by traditional methods are the subjectivity of methods and the availability of adequately trained analysts. This chapter also includes an overview of more sophisticated techniques to pinpoint the nature and source of contaminants (X-ray radiography, X-ray microtomography, electrical conductance, olfaction, impact-acoustic emission, microscopy techniques, near-infrared spectroscopy, artificial intelligence, molecular methods, and enzyme-linked immunosorbent assays).
The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a major storage pest that could lead to a wide range of damage. Its secretions have a significant impact on the quality of stored grain and food, leading to serious food safety problems such as grain spoilage and food carcinogenesis. This study investigates new detection techniques for grain storage pests to improve grain insect detection in China. The primary volatile organic chemicals (VOCs) in these secretions are identified using headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). The specific VOCs that are unique to T. castaneum are selected as criteria for determining the presence of T. castaneum in the granary. To obtain more specific VOCs, experiments were designed for the analysis of T. castaneum samples under different extraction times, two types of SPME fibers and two GC-MS devices of different manufacturers. The experimental results showed that 12 VOCs were detected at relatively high levels, seven of which were common and which were not detected in other grains and grain insects. The seven compounds are 1-pentadecene, 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone, 1-hexadecene, cis-9-tetradecen-1-ol, m-cresol and paeonol. These seven compounds can be used as volatile markers to identify the presence of T. castaneum, which could serve as a research foundation for the creation of new techniques for T. castaneum monitoring.
Insect infestation of agricultural stored products is a significant challenge to food security across the globe. One common pest is Tribolium castaneum (red flour beetle). In a new approach to addressing the threat of these beetles, Direct Analysis in Real Time-High-Resolution Mass Spectrometry was used to examine infested and uninfested flour samples. These samples were then distinguished through statistical analysis techniques, including EDR-MCR, in order to highlight the important m/z values contributing to the differences in the flour profiles. A subset of these values responsible for the identification of infested flour (nominal m/z 135, 136, 137, 163, 211, 279, 280, 283, 295, 297, and 338) were further investigated, and compounds responsible for these masses included 2-(2-ethoxyethoxy)ethanol, 2-ethyl-1,4-benzoquinone, palmitic acid, linolenic acid and oleic acid. These results have the potential to lead to a rapid technique by which flour and other grains can be tested for insect infestation.
This volume intends to describe the quality analysis methods for food items coupled with artificial intelligence. This primarily covers analytical methods including spectroscopic techniques and chromatographic methods. The volume begins with an introductory chapter elaborating on the importance of food quality analysis and discusses the different approaches for compositional and chemical analysis. This chapter also highlights the importance of food quality analysis in particular reference to pandemic times. Spectroscopic techniques including Fourier transform infrared, fluorescence, and Raman spectroscopy have been covered in the following chapters. Multivariate analysis and applications of different sophisticated statistical tools have been included in these chapters in addition to the basic principles involved. A wide range of food items have been covered, which include fats and oils, beer, and other pharmaceutical materials.
The study aimed to investigate the capability of bath-ultrasonication and its combination with conventional water-bath and autoclave treatment in modifying the volatile composition of brewers’ spent grain (BSG). It was hypothesized that the treatments modified the volatile composition of BSG due to the sonochemical modification. The results demonstrated that the treatments intensified the desirable odor and removed the undesirable one which might allow the possibility of masking and renewing the odor perception of BSG. Besides the influence on odor perception related compounds, it is worth to highlight that the treatments eliminated herbicidal compounds such as (E,E)-2,4-heptadienal and (E)-2-hexenal which might be present from herbicidal treatment. Combination of bath-ultrasonication with autoclave treatment modified the volatile aldehydes while its combination with conventional water-bath generated the same profile as it was in untreated BSG. Time elevation on bath-ultrasonication had no significant impact on the amount of ketones and alkanes, while the fluctuation occurred as an impact of thermal exposures. Moreover, the treatment reduced the amount of alcohol and increased the fatty acids. In conclusion, bath-ultrasonication and its combination with thermal exposure modified the volatile compositions of BSG.
Integrated pest management technology of stored grain pests is an all-time evolving process worldwide. These pests have become the global importance due to their severity in the pre- and post-harvest periods, leading to the huge loss of grains during storage. In nature, they are cosmopolitan and present every nook and corner of this world, they have gained attention from the field to the scientists to develop strategies to overcome their problems in many countries. To tackle this issue integrated practices are to be followed from field to storage structure. At first, zestful monitoring and detection of the external and internal storage insect following various methods is the prime important factor for planning the future management tactics to be practiced. To protect the grains well in advance, several preventative measures by adopting cultural practices can be achieved, if once an infestation is confirmed the curative methods such as physical, mechanical, biological, and chemical as a last resort are used to manage the pests. As the stored grain pests are continuously developing and resulting in failure of management practices, so entomologists should involve in the constant research in designing novel techniques in order to manage and compete with insect pests to protect our produce during storage so that the global hunger can be mitigated efficiently.
For stored grains and their powders, pest infestation has always been a knotty problem and thus comprises a serious threat to global food security. Obviously, timely, rapid and accurate pest detection methods are of extreme importance to protect grains from pest mouth. In facing the defects of traditional methods, such as visual inspection, grain flotation and pest trap, diverse innovative approaches progressed fast alternatively, either targeting pest itself or diagnosing pest-induced changes. The former includes machine vision, metabolite analysis, pest-specific protein techniques, molecular techniques, bioacoustics analysis, conductive roller mill, low-field nuclear magnetic resonance spectroscopy and imaging, while the latter consists of thermal imaging, near-infrared spectroscopy and hyperspectral imaging, impact acoustics analysis, soft X-ray imaging and tomography. The principle, operation procedure, pros and cons and application scenarios were discussed for each method. The results herein hope to promote the technical revolution of pest inspection in stored cereal grains and their powders.
Tribolium castaneum, a secondary pest that feeds on processed stored grains, can cause serious damage on stored grain. To reduce the loss of stored grain caused by pest infestation, monitoring and early detection of insects are essential. volatile compounds arising from insects or insect-infested stored products can be appropriate biomarkers. In this study, gas chromatography–mass spectrometry (HS-SPME-GC-MS) was used to qualitatively and quantitatively identify the volatile compounds of brown rice infested by T. castaneum under different temperatures (10 °C, 20 °C, 30 °C). Moreover, some characteristic volatile compounds were identified by partial least square-discrimination analysis (PLS-DA). Seventy-one volatile compounds, including 12 aldehydes, 11 alcohols, 21 esters, 10 ketones, 13 hydrocarbons and some other compounds, were detected in the brown rice samples infested by T. castaneum. Twenty-three characteristic volatile compounds, which had a variable importance in projection (VIP) more than 1, were identified by PLS-DA. Among them, 1-pentadecene was detected only in infested brown rice, can be used as a potential volatile biomarker for the presence of T. castaneum in brown rice during storage and transportation process.
Studies of insect movement are hampered by the small size of insects and the associated difficulty in tracking them in the environment. We tested the potential of quantum dots (QDs) to mark large numbers of insects very quickly. Our results demonstrate that green CdTe (cadmium tellurium) QDs were effective markers in the laboratory and can be applied to large numbers of insects very easily. Successful recaptures in the field demonstrate that QDs have great potential as external markers. Studies of insect movement are hampered by the small size of insects and the associated difficulty in tracking them in the environment. We tested the potential of quantum dots (QDs) to mark large numbers of insects very quickly. Our results demonstrate that green CdTe (cadmium tellurium) QDs were effective markers in the laboratory and can be applied to large numbers of insects very easily. Successful recaptures in the field demonstrate that QDs have great potential as external markers.
To reduce food loss from stored products by insect attack, monitoring and early detection of insects are essential. Presently, monitoring with pheromone traps is the primary method for detection; however, traps are effective only after the insects propagate. Detection and identification of the early volatile biomarkers arising from insect-infested brown rice was performed in this study to develop an alternative detection strategy. Brown rice was infested with eggs of seven insect species, including Sitophilus zeamais and Plodia interpunctella. Infested rice emitted at least one of the volatile compounds prenol, isoprenol, dimethyl disulfide, and dimethyl trisulfide (DMTS). In particular, isopentenols were generated by moths within one week of infestation, whereas they were not released from non-infested rice. DMTS was detected from all insect-infested brown rice, especially S. zeamais and P. interpunctella. These volatiles are potential early biomarkers for the presence of insects in brown rice.
Dust derived from food processing can accumulate in places difficult to reach, where stored-product pests could thrive. The purpose of this work was to verify the development of Plodia interpunctella, Ephestia kuehniella, and Tribolium castaneum in dust collected on pipes and beams (15 m and 7.5 m) in a silo area of a pasta industry. Proximate analyses showed a higher metal content in the dust collected at the two different heights than semolina, including the presence of chrome, cobalt, arsenic, and lead. Particle size distribution analysis showed that in the two samples of dust the highest percentage was constituted by particle sizes smaller than 106 μm. The tests were carried out by using two quantities 4 g or 0.15 g of dust (corresponding to 3 mm and 0.1 mm), at controlled conditions. Fifty larvae, 0–24 h old, of each species, were used for each dust, semolina, and thickness test. The number of emerged adults was assessed daily. T. castaneum developed on all the tested substrates, despite the high content of metals and the small particle size in the environmental dust. A significant interaction between diet and thickness of the layer was observed, but thickness had a stronger influence than diet. Moreover, light filth analysis detected a large number of fragments of Tribolium sp. in dust collected at a different height. Dust was unsuitable for the development of moths; only two E. kuehniella adults emerged from 3-mm-deep dust collected at 15 m, and development lasted more than 90 d.
In the present work, the characteristics of carbon dioxide (CO2) produced by insects and fungi were studied under different wheat storage conditions with varying temperatures and moisture contents. The findings could be useful for determining the storage safety of wheat. The results showed that storage temperature had the most dramatic effects on the rate of CO2 production by fungi during growth. When the storage temperature rose from 20℃ to 25℃, the CO2 production rate increased by ten-fold. Gas was mainly produced by insects in wheat with moisture in the safe range, while fungi were the main producers in high-moisture wheat. In terms of CO2 production characteristics, there was a linear relationship between insect density and CO2 production quantity (r > 0.99), and gas production by fungi appeared accelerated. The gas production rate increased by 5. 96-fold when fungal counts in wheat did not change significantly (p > 0.05) during early storage. In large-scale wheat warehouse experiments, the gas production rate of insects was stable, and the CO2 concentration fluctuation rate was 13% at 25 days in the 4-m-deep area of the wheat bulk, at which insects carried out their activities. In comparison, the changes in CO2 concentrations were 37-fold at locations 0.5 m from mold spots. Therefore, the harmful activities of insects and fungi in stored wheat could be sensitively monitored by CO2 detection. ©, 2015, South China University of Technology. All right reserved.
During storage, grain can experience significant degradation in quality due to a variety of physical, chemical, and biological interactions. Most commonly, these losses are associated with insects or fungi. Continuous monitoring and an ability to differentiate between sources of spoilage are critical for rapid and effective intervention to minimize deterioration or losses. Therefore, there is a keen interest in developing a straightforward, cost-effective, and efficient method for monitoring of stored grain. Sensor arrays are currently used for classifying liquors, perfumes, and the quality of food products by mimicking the mammalian olfactory system. The use of this technology for monitoring of stored grain and identification of the source of spoilage is a new application, which has the potential for broad impact. The main focus of the work described herein is on the fabrication and optimization of a carbon black (CB) polymer sensor array to monitor stored grain model volatiles associated with insect secretions (benzene derivatives) and fungi (aliphatic hydrocarbon derivatives). Various methods of statistical analysis (RSD, PCA, LDA, t test) were used to select polymers for the array that were optimum for distinguishing between important compound classes (quinones, alcohols) and to minimize the sensitivity for other parameters such as humidity. The performance of the developed sensor array was satisfactory to demonstrate identification and separation of stored grain model volatiles at ambient conditions.
Two synergistic macrolide aggregation pheromones were isolated from Porapak Q-trapped volatiles obtained from the frass ofCryptolestes ferrugineus (Stephens). These compounds were identified as (E,E)-4,8-dimethyl-4,8-decadien-10-olide (I) and (3Z,11S)-3-dodecen-11-olide (II) and given the trivial names ferrulactone I and II, respectively. Analysis of captured volatiles from separated male and female adults disclosed that the pheromones are male-produced. Additional macrolides were identified in frass volatiles, but were devoid of any pheromonal activity. The structures of I and II were confirmed by comparison with synthetic materials.
The accumulation of quinone secretions, from the abdominal and thoracic defence glands of adult Tribolium castaneum, was investigated in dehusked rice of four different milling degrees. Three quinones were detected in measurable quantities, 2-methyl-1,4-benzoquinone, 2-ethyl-1,4-benzoquinone and 2-ethylhydroquinone, but these were present at very low concentrations. Even after substantial exposure to adults, equivalent to an adult-week product of 1345 on 80 g of rice, the combined total contamination with these three compounds was only about 1.0 ppm. The accumulation rate of quinones in the samples was estimated to range from 0.0470 to 0.0631μg/adult/week and seemed unaffected by the milling degree of the rice. However, the distribution of quinone contamination in the samples between the rice grain and insect frass was influenced by milling degree. In unpolished rice, about 80% of quinone contamination was in the rice itself rather than in the frass, while in rice of 95% milling degree the contamination was more or less evenly distributed.The low quinone contamination rates observed in rice suggest that the accumulation of these chemicals is unlikely to pose a serious health threat when rice is exposed to ‘normal’ rates of infestation by T. castaneum for typical storage periods, e.g. 6–12 months. Even the highest observed degree of contamination, 1.0 ppm, would in theory take about 32 y to accumulate if adult beetles remained at a relatively high average density of 10 adult T. castaneum/kg. These conclusions require confirmation by direct observation of rice after long-term warehouse storage in the tropics.
The solid phase microextraction (SPME) technique was used for the collection of the volatile defensive secretions released by Tribolium castaneum (Herbst), the red flour beetle. The detection of the major components methyl-1,4-benzoquinone (MBQ) and ethyl-1,4-benzoquinone (EBQ), together with 1-pentadecene (C15:1), was performed by capillary gas chromatography (CGC). SPME samples were identified by CGC coupled to mass spectrometry (MS). Volatile organic compounds (VOC) released from insects were compared employing different SPME fibers. The relative amounts of the major volatiles collected varied with the fiber coating. Quinones accounted for ∼75% of the volatiles trapped by the carboxen/polydimethylsiloxane (CAR/PDMS) fiber, whereas they only represented ∼45% of the volatiles trapped with the PDMS fiber. The PDMS/divinylbenzene (DVB) coating exhibited intermediate affinity. In a 15-min extraction period, the highest amounts of VOC extracted from disturbed insects with CAR/PDMS were 349±107ng/beetle of MBQ, 780±290ng/beetle of EBQ, and 144±69ng/beetle of C15:1. The total VOC amounts extracted by SPME were estimated by adding the disturb-released VOC to heat-released VOC of the same insects, resulting in 742±93ng/beetle of MBQ, 1672±244ng/beetle of EBQ, and 946±237ng/beetle of C15:1. SPME-CGC is a simple method to detect and estimate T. castaneum volatiles. This method has the potential to detect insect infestation in stored products.
Trapping of insects in small bins of stored wheat was conducted during 1984 and 1985 in an unheated building in Winnipeg, Manitoba, Canada. Tubular brass-screen traps consisting of six distinct vertical sections were positioned in the center of each bin to full depth of the grain. Each bin contained 218 kg of wheat and adults of both the red flour beetle, Triboltum castaneum (Herbst), and the rusty grain beetle, Cryptolestes ferrugineus (Stephens), at densities of 1, 5, and 10 insects of each species per kilogram of wheat. About 57% of T. castaneum was captured in 6 weeks in 1984 at grain temperatures of 21-24, regardless of insect density, using unbaited traps; for C. ferrugineus, 23% was captured at the 10 adults per kilogram density compared with ca. 14% at 1 or 5 per kilogram. T. castaneum was consistently more abundant in the top 6-10 cm of the wheat while C. ferrugineus was more abundant at and near floor level. Traps baited with either wheat germ or adults of both species caught ca. 16%, and unbaited traps caught 6%, of the initial T. castaneum population during a 5-week period in 1984 at grain temperatures ranging from 15 to 3. During that period, traps baited with insects or with wheat germ caught 11 and 5%, respectively, of the C. ferrugineus population, while unbaited traps caught 6%.At grain temperatures > 17°C in 1985, 2- to 3-fold more T. castaneum and C. ferrugineus were usually caught in traps with wheat germ. More T. castaneum were caught at the top periphery of the bin than at the top-central location. Grain sampling probes were not reliable for detecting either insect species.
An energy budget was determined for Cynaeus angustus (LeConte) reared singly on split corn kernels at 30 ± 1°C and 80 ± 5% RH, the efficiencies of energy use calculated, and comparisons of bioenergetic data made with eight other stored-product insects. Average energy in joules (J) accumulated in biomass per individual in the developmental stages was as follows: egg, 1; first instar (L1), <1; L2, <1; L3, 1; L4, 2; L5, 5; L6, 3; L7, 18; L8, 20; L9, 39 J. The mean energy content of one corn kernel was 4,076 J. A mean of 30.99 mg of corn (598 J) was ingested during development and ca. 444 mg of corn (8,569 J) could be ingested during a 100-d adult period. During development, 206 J were lost as feces. The highest rate of O2 consumption (88 µl O2·mg−1·h−1) occurred in L2 on day 10, but most oxygen was consumed by L9 on day 46 (25 µl O2 per individual per h). During the 64-d developmental period, 247 J were lost through respiration and 88 J were used for growth. Mean assimilation efficiency was 55.5% for larvae and 66.0% for adults; mean gross production efficiency was 14.7% for larvae and 4.9% for adults; mean net production efficiency was 26.5% for larvae and 7.5% for adults. In comparison with other storage insects with known energy budgets, C. angustus was the largest beetle; larval consumption was greater than that of other beetles but similar to that of the moths, Plodia interpunctella (Hübner) and Ephestia cautella (Walker); total adult consumption was greater than that in the other storage insects; efficiencies of energy use by immatures were near those of Tribolium castaneum (Herbst), Cryptolestes ferrugineus (Stephens), and P. interpunctella.
A carbon dioxide sensor was developed using polyaniline boronic acid conducting polymer as the electrically conductive region of the sensor and was demonstrated for use in detecting incipient or ongoing spoilage in stored grain. The developed sensor measured gaseous CO2 levels in the range of 380–2400 ppm of CO2 concentration levels. The sensor was evaluated for the influence of temperature (at - 25 °C to simulate storage and for the operating temperature range of +10 °C to +55 °C) as well as relative humidity (from 20 to 70%). The variation in the resistance with humidity was curvilinear and repeatable, and had a less pronounced effect on the sensor’s performance compared to temperature. The sensor was able to respond to changes in CO2 concentration at various humidity and temperature levels. The response of the PABA film to CO2 concentration was not affected by the presence of alcohols and ketones at 1% of vapour pressure, proving that the developed sensor is not cross-sensitive to these compounds which may be present in spoiling grain. The sensor packaging components were selected and built in such a way as to avoid contamination of the sensing material and the substrate by undesirable components including grain dust and chaff. The developed conducting polymer carbon dioxide sensor exhibited effective response, recovery time, sensitivity, selectivity, stability and response slope when exposed to various carbon dioxide levels inside simulated grain bulk conditions.
An autosampler attached to a purge and trap instrument was used to aid routine analyses of grain samples for volatile compounds associated with off-odors. Trapped volatiles were transferred to a gas chromatograph/mass spectrometer instrument for separation and detection. Dynamic extraction of volatiles from approximately 18 g of whole grain at 80 degrees C was accomplished by purging helium through a sample vial with a Teflon-lined septum on each end. The autosampler automatically added internal standard to the sample before purging began, which required the addition of 1 mL of water for complete transfer of the standard to the sample. The added water enhanced extraction of 1-octen-3-ol, 1-octen-3-one, and some other compounds from soybeans but not from starchy grains such as corn and wheat. Addition of a free radical scavenger, such as citric acid, greatly diminished the recovery of 1-octen-3-ol and 1-octen-3-one from soybeans.
Headspace techniques have traditionally involved the collection of volatiles in the vapor state under either dynamic or static conditions as a means of determining concentrations in the product of interest. A brief overview of contemporary headspace applications and recent innovations are presented from the literature and Chapters in this book. New approaches used to concentrate volatiles under static conditions such as solid phase micro extraction, SPME, are examined. Advances in purge and trap applications and automation are also presented. Innovative methods of evaluating headspace volatiles using solid state sensor arrays (electronic noses) or mass spectrometers without prior separation are referenced. Numerous food and beverage headspace techniques are also reviewed. Advantages, limitations and alternatives to headspace analysis are presented.
Distribution and movement patterns of several species of stored-product pests in a food processing plant were investigated. The objectives of this study were to determine the temporal and spatial variation in abundance of stored-product pests using pheromone traps; assess the effectiveness of trap type, location, and number on monitoring insect populations; and to evaluate the nature of pheromone trap capture hot spots by measuring patterns of insect movement. We determined that the distributions of Trogoderma variabile Ballion, Lasioderina serricorne (F.), Tribolium castaneum (Herbst), and Plodia interpunctella (Hübner) within the facility were typically clumped and that foci of high trap captures, based on visual observation of contour maps, varied among species and over time. Trap type and location influenced the number of T. variabile captured: traps on the floor and along walls captured more individuals than hanging traps and traps next to support pillars. T. variabile was the predominant insect pest at this facility and from mark-recapture studies, we found that individual beetles moved across multiple floors in the facility and from 7 to 216 m though the warehouse.
Males of the genus Parastizopus (Coleoptera: Tenebrionidae) exhibit a special pheromone-emitting behaviour. They do a headstand, expose the aedeagus and remain in this posture for a few seconds. The pheromone emitted by P. transgariepinus was collected by solid-phase micro-extraction (100 microm polydimethylsiloxane fibre) and identified as 1-tridecene by gas chromatography/mass spectrometry. Presumably, this compound originates from the aedeagal gland, a special feature in Parastizopus, as 1-tridecene is the main compound in the gland reservoirs (23.6+/-3.8%), accompanied by various less volatile fatty acid esters (25.2+/-2.0%) and hydrocarbons (51.2+/-5.7%). 1-Tridecene is also part of the pygidial defensive secretion of both sexes, together with other 1-alkenes, monoterpene hydrocarbons and 1,4-benzoquinones, but as none of these other compounds was detected during calling, the pygidial gland could be ruled out as pheromone source. Extracts of the aedeagal gland reservoirs and the pygidial defensive secretion contained comparable amounts of 1-tridecene, 1.24+/-0.41 and 1.88+/-0.54 microg/male, respectively. Chemo-orientation experiments using a servosphere showed that 1 microg of 1-tridecene was attractive to females but not to males.
Variety Survey 2009 10
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Statistical Tables Canadian Grain Exports Crop Year 2008 09
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Moisture Measurement e Unground Grain and Seeds ASAE S352.2. ASABE standards 555
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Quinone contamination of dehusked rice by Tribolium castaneurn (Herbst) (Coleoptera: Tenebrionidae) Mathematical modeling of heat, moisture, and gas transfer in stored grain ecosystems Stored Grain Ecosystems
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Hodges, R.J., Robinson, R., Hall, D.R., 1996. Quinone contamination of dehusked rice by Tribolium castaneurn (Herbst) (Coleoptera: Tenebrionidae). Journal of Stored Products Research 32, 31e37. Jayas, D.S., 1995. Mathematical modeling of heat, moisture, and gas transfer in stored grain ecosystems. In: Jayas, D.S., White, N.D.G., Muir, W.E. (Eds.), Stored Grain Ecosystems. CRC Press, New York, pp. 527e567.
Monitoring stored-products pests in food processing plants with pheromone trapping, contour mapping, and mark recapture Statistical Tables. Canadian Grain Exports Crop Year 2008e09 Food and Agricultural Organization of United Nations
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Headspace analysis of foods and flavours theory and practice
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Rouseff, R.L., Cadwallader, K.R., 2001. Headspace analysis of foods and flavours theory and practice. Advances in Experimental Medicine and Biology 488, 1e8.
Mathematical modeling of heat, moisture, and gas transfer in stored grain ecosystems Stored Grain Ecosystems
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faostat.fao.org Rome, Italy.
Moisture Measurement Unground Grain and Seeds ASAE S352
ASABE, 2008. Moisture Measurement
Unground Grain and Seeds ASAE S352.2.
Chromatograms of the 15% moisture content wheat and three T. castaneum adults (top) and 15% moisture content wheat and five T. castaneum adult insects (bottom). 1: methyl-1,4-benzoquinone
- Fig
Fig. 8. Chromatograms of the 15% moisture content wheat and three T. castaneum
adults (top) and 15% moisture content wheat and five T. castaneum adult insects
(bottom). 1: methyl-1,4-benzoquinone; 2: ethyl-1,4-benzoquinone; 3: 1-tridecene.
Mathematical modeling of heat, moisture, and gas transfer in stored grain ecosystems
- Jayas
Monitoring stored-products pests in food processing plants with pheromone trapping, contour mapping, and mark recapture
- Campbell