Toxicological effects of the fungal volatile compound 1-octen-3-ol against the red flour beetle, Tribolium castaneum (Herbst)

Megalurothrips usitatus Feeding-Induced De Novo Synthesis of the C8 Volatiles 1-Octen-3-ol and 2-Ethyl-1-hexanol in Cowpea Plants Regulates Plant-Herbivore-Predator Interactions

Analyzing the role of herbivore-induced volatiles in plant-herbivore-natural enemy interactions is crucial for developing integrated pest management strategies. This study identified 1-octen-3-ol and 2-ethyl-1-hexanol as the primary C8 volatiles induced by Megalurothrips usitatus infestation in cowpea flowers. The concurrent accumulation of glycosides of these volatiles, along with the upregulation of LOX and HPL expression, suggested that the increased emissions of 1-octen-3-ol and 2-ethyl-1-hexanol result from enhanced de novo biosynthesis regulated by herbivore-induced jasmonate. 1-Octen-3-ol exhibited strong repellent effects against M. usitatus and attracted its natural enemy, Orius similis, at low concentrations. By contrast, 2-ethyl-1-hexanol repelled M. usitatus but did not exert a significant attractant effect on O. similis. These volatiles prime the defense mechanism in cowpea plants against M. usitatus, which highlight their promising role in controlling thirp populations and enhancing cowpea cultivation.

An insight into specific flavor sensation in fermented milk: Linalool and mushroom alcohol

Flavor perception plays a decisive role in consumer choice of dairy products. That confer overall flavor formation, far less is known about the critical flavor compound of the specific sensory, particularly for fermentation aroma and off-flavor perception. Here in fine details, we resolved the volatile flavor compounds in dairy products by Lactobacillus casei or Lactobacillus bulgaricus with prolonged fermentation process using the headspace-solid phase micro-extraction (HS-SPME) and gas chromatography mass spectrometry (GC-MS), and 49 and 47 volatile flavor compounds were identified, respectively. Chemometrics combined with Odor Activity Value calculations identified 7 key flavor components (OAV > 1). Correlations between sensory attributes and flavor components were then investigated and market validation revealed the role of 2 compounds, linalool and shiitake alcohol, in conferring fermentation aroma and off-flavor perception, respectively. Overall, these results provide a potential target for the detection and development of high-quality dairy products and provide an example for the exploration of specific sensory flavor compounds in the food industry.

Efficacy of the Combination of λ-Cyhalothrin and Chlorantraniliprole Against Four Key Storage Pests

With over 1000 species of pests causing losses in both the quantity and quality of stored food, insect contamination poses significant challenges. The present study assesses the efficacy of the combination of λ-cyhalothrin and chlorantraniliprole against four key storage pests-Trogoderma granarium, Sitophilus oryzae, Rhyzopertha dominica, and Tribolium castaneum. Laboratory bioassays demonstrated species-dependent mortality, with S. oryzae and R. dominica suffering 100% mortality in several tested scenarios. A 90-day persistence trial revealed decreased efficacy over time, especially for T. granarium (32.0-71.4% at 0 days and 0.0-7.5% at 90 days) and T. castaneum (38.8-82.7% at 0 days and 0.0-12.7% at 90 days) vs. S. oryzae and R. dominica. Progeny production of S. oryzae and R. dominica was almost suppressed in persistence trials (0.4 individuals per vial and 1 individual per vial, respectively) after 30 days of storage at the dose of 5 mg/kg wheat. The results highlight the variability in insecticidal performance based on species, dose, exposure, and commodity type, emphasizing the need for tailored pest management strategies in the storage environment.

A winning formula: sustainable control of three stored-product insects through paired combinations of entomopathogenic fungus, diatomaceous earth, and lambda-cyhalothrin

This research aimed to assess the effectiveness of Metarhizium robertsii, diatomaceous earth (Protect-It), and lambda-cyhalothrin, for the long-term protection of stored wheat against three destructive grain insect pests, Rhyzopertha dominica, Tribolium castaneum, and Trogoderma granarium. Different treatments were applied, both alone and in paired combinations in laboratory and persistence trials. Single treatments exhibited significantly lower mortality rates in comparison to the paired treatments for all tested insect species. Among the single treatments, lambda-cyhalothrin (Lamb) resulted in significantly higher mortality rates in laboratory trials, followed by diatomaceous earth (DE) and M. robertsii (Mr), with insignificant differences between Mr and DE. Evidently, DE exhibited the highest persistence after 120 days of storage for all insect species and initial exposures, although variations in mortality rates among treatments were mostly insignificant. Overall, the most effective treatment in terms of mortality in laboratory, and persistence trials, and progeny production was DE + Lamb, followed by Mr + Lamb, and Mr + DE for all tested insect species. In general, the most susceptible insect species was R. dominica, followed by T. castaneum and T. granarium. This research highlights the effectiveness of M. robertsii, DE, and lambda-cyhalothrin in providing prolonged protection of stored wheat against all the examined grain insect species.

Screening for insecticidal toxicity of Urginea maritima (L.) bulbs and Asphodelus microcarpus (L.) tubers for the control of Tribolium castaneum (Tenebrionidae)

This research was conducted to determine the effect of geographical distribution on morphological characteristics of plants and some chemical compounds such as polyphenols. Moreover, we explore the contact toxicity of ethanolic and methanolic extracts from Urginea maritima bulbs and Asphodelus microcarpus tubers collected from three localities in the North West of Tunisia against Tribolium castaneum adults. The toxicity results demonstrated that both of the studied plant extracts had an effective control against T. castaneum at concentration 7.5 µL/L air, thus total mortality reached. In addition, results showed plant extracts with methanol exhibited high mortality percentage of T. castaneum.   On the other hand, results revealed that chemical composition of U. maritime bulbs and A. microcarpus tuber extract depends on the soil components and geographical distribution of plants. The present investigation confirmed that A. microcarpus and U. maritima may be recommended as an eco-friendly alternative to synthetic insecticide against T. castaneum.

Volatile Fingerprint Mediates Yeast-to-Mycelial Conversion in Two Strains of Beauveria bassiana Exhibiting Varied Virulence

Beauveria bassiana is a dimorphic and entomopathogenic fungus with different ecological roles in nature. In pathogenic fungi, yeast-to-mycelial conversion, which is controlled by environmental factors, is required for virulence. Here, we studied the effects of different stimuli on the morphology of two B. bassiana strains and compared the toxicities of culture filtrates. In addition, we explored the role of volatiles as quorum sensing-like signals during dimorphic transition. The killing assays in Caenorhabditis elegans (Nematoda: Rhabditidae) showed that strain AI2 isolated from a mycosed insect cadaver had higher toxicity than strain AS5 isolated from soil. Furthermore, AI2 showed earlier yeast-to-mycelial switching than AS5. However, an increase in inoculum size induced faster yeast-to-mycelium conversion in AS5 cells, suggesting a cell-density-dependent phenomenon. Gas chromatography-mass spectrometry (GC-MS) analyses showed that the fingerprint of the volatiles was strain-specific; however, during the morphological switching, an inverse relationship between the abundance of total terpenes and 3-methylbutanol was observed in both strains. Fungal exposure to 3-methylbutanol retarded the yeast-to-mycelium transition. Hence, this study provides evidence that volatile compounds are associated with critical events in the life cycle of B. bassiana.

Evaluating the Compatibility of Spinosad and Alpha-Cypermethrin for Controlling Six Insect Pests Infesting Stored Wheat

The deterioration of stored wheat due to pest infestations is a significant concern, with pests like Rhyzopertha dominica, Tribolium castaneum, Cryptolestes ferrugineus, Sitophilus oryzae, Oryzaephilus surinamensis, and Trogoderma granarium being major contributors. This study examined the efficacy of spinosad and alpha-cypermethrin, individually and in combination, against these pests under laboratory conditions. Spinosad was tested at two concentrations (0.05 and 0.1 mg/kg), while alpha-cypermethrin was applied at 0.05 mg/kg. The combined application of both insecticides led to significantly higher pest mortality compared to single treatments. Importantly, all treatments caused substantial pest mortality and exhibited the ability to suppress pest progeny production over time, as observed in both laboratory and persistence trials. Among the various treatment combinations, the joint application of 0.1 mg/kg spinosad and 0.05 mg/kg alpha-cypermethrin emerged as the most effective, resulting in elevated mortality and a marked reduction in pest progeny. Rhyzopertha dominica exhibited the highest susceptibility among the pests, followed by S. oryzae, T. castaneum, C. ferrugineus, O. surinamensis, and T. granarium. The remarkable performance of the joint action of alpha-cypermethrin and spinosad at low doses highlights this combination as an efficacious approach for safeguarding stored grain against these destructive insect pests, warranting further exploration.

Development of a novel 1-octen-3-ol-loaded agar/curdlan hydrogel for inhibiting peach fruit diseases

Our previous study found that 1-octen-3-ol fumigation treatment could effectively induce the resistance of peach fruit diseases. However, 1-octen-3-ol is a liquid fumigant, which is not conducive to storage and application. Herein, the gel of 1 % agar compound with 1 % curdlan was used as a novel material for covering 1-octen-3-ol. The interaction of agar and curdlan was promoted by adding 1-octen-3-ol, leading to a higher thermostability compared to single-component antibacterial gels. Moreover, 1-octen-3-ol resulted in changes in the internal structure and mechanical properties of gel to form a pore-like structure, which is beneficial to the retention and release of 1-octen-3-ol. Additionally, the 2 % agar gel containing 1-octen-3-ol had the best inhibitory effect on the mycelial growth of Monilinia fructicola and Rhizopus stolonifer in vitro, and the compound hydrogel of 1 % agar and 1 % curdlan with 1-octen-3-ol could most effectively inhibit brown rot and soft rot caused by these two pathogens in vivo. Overall, the data indicated that the novel 1-octen-3-ol-loaded agar/curdlan hydrogels could effectively retain and release 1-octen-3-ol, and induce the resistance of peach fruit diseases.

A Faboideae-Specific Floral Scent Betrays Seeds to an Important Granivore Pest

Seed predation by insect herbivores reduces crop production worldwide. Foraging on seeds at pre-dispersal generally means that females need to find the suitable host plant within a relatively short timeframe in order to synchronize larval development with seed production. The mechanistic understanding of host finding by seed pests can be harnessed for more sustainable pest management strategies. We here studied the chemical communication between the bean bug Riptortus pedestris, a major pest of legumes, and several crop species and cultivars in the Fabaceae. Via a comparative chemical analysis, we found that 1-octen-3-ol is the principal constituent of the floral scents of most species tested in the subfamily Faboideae, including soybean and faba bean. With field trapping and laboratory bioassays, including electroantennography, we further revealed that this compound can be perceived, and stimulate attraction responses, by R. pedestris nymphs and adults. The addition of 1-octen-3-ol to pheromone traps might therefore improve trapping efficacy for controlling populations of this important granivore pest on legumes.

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

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

HS-SPME-GC-MS Untargeted Analysis of Normal Rat Organs Ex Vivo: Differential VOC Discrimination and Fingerprint VOC Identification

The investigation of volatile organic compounds (VOCs) in human metabolites has been a topic of interest as it holds the potential for the development of non-invasive technologies to screen for organ lesions in vivo. However, it remains unclear whether VOCs differ among healthy organs. Consequently, a study was conducted to analyze VOCs in ex vivo organ tissues obtained from 16 Wistar rats, comprising 12 different organs. The VOCs released from each organ tissue were detected by the headspace-solid phase microextraction-gas chromatography-mass spectrometry technique. In the untargeted analysis of 147 chromatographic peaks, the differential volatiles of rat organs were explored based on the Mann-Whitney U test and fold change (FC > 2.0) compared with other organs. It was found that there were differential VOCs in seven organs. A discussion on the possible metabolic pathways and related biomarkers of organ differential VOCs was conducted. Based on the orthogonal partial least squares discriminant analysis and receiver operating characteristic curve, we found that differential VOCs in the liver, cecum, spleen, and kidney can be used as the unique identification of the corresponding organ. In this study, differential VOCs of organs in rats were systematically reported for the first time. Profiles of VOCs produced by healthy organs can serve as a reference or baseline that may indicate the presence of disease or abnormalities in the organ's function. Differential VOCs can be used as the fingerprint of organs, and future integration with metabolic research may contribute to the development of healthcare.

Fungal volatiles have physiological properties

All fungi emit mixtures of volatile organic compounds (VOCs) during growth. The qualitative and quantitative composition of these volatile mixtures vary with the species of fungus, the age of the fungus, and the environmental parameters attending growth. In nature, fungal VOCs are found as combinations of alcohols, aldehydes, acids, ethers, esters, ketones, terpenes, thiols and their derivatives, and are responsible for the characteristic odors associated with molds, mushrooms and yeasts. One of the single most common fungal volatiles is 1-octen-3-ol also known as "mushroom alcohol" or "matsutake alcohol." Many volatiles, including 1-octen-3-ol, serve as communication agents and display biological activity as germination inhibitors, plant growth retardants or promoters, and as semiochemicals ("infochemicals") in interactions with arthropods. Volatiles are understudied and underappreciated elements of the chemical lives of fungi. This review gives a brief introduction to fungal volatiles in hopes of raising awareness of the physiological importance of these gas phase fungal metabolites to encourage mycologists and other biologists to stop "throwing away the head space."

The Potential of Two Entomopathogenic Fungi and Enhanced Diatomaceous Earth Mixed with Abamectin: A Comprehensive Study on Mortality, Progeny Production, Application Method, and Surface Application against Tribolium castaneum

This study determined the efficacy of Beauveria bassiana (Bals. -Criv.) Vuill., Metarhizium anisopliae (Metchnikoff) Sorokin, and diatomaceous earth mixed with abamectin (DEA) alone and in their combinations for the integrated management of larvae and adults of Tribolium castaneum (Herbst) from three field populations of Pakistan (Multan, Rawalpindi, and Rahim Yar Khan) and one laboratory population (Faisalabad). Treatments were applied on three surfaces, namely, viz. steel, concrete, and jute bags, implementing two application methods, dusting and spraying. The combined treatments were more effective in comparison with single treatments for both larvae and adults. Overall, the highest mortality rates were recorded in the Faisalabad population, followed by the Rehaim Yar Khan, Rawalpindi, and Multan populations. Progeny production was suspended 21 days after exposure to the combined treatment of DEA and both fungi in all populations except Rawalpindi. Larvae were found to be more susceptible than adults in all treatments and intervals. Dusting was more efficient than spraying for both larvae and adults and for all the populations studied. The present study provides a wholistic understanding of the impact of different factors on the success of the combined treatments using DEA and entomopathogenic fungi, supporting their use as surface treatments.

Dietary Grape Pomace Supplementation in Lambs Affects the Meat Fatty Acid Composition, Volatile Profiles and Oxidative Stability

The aim of this study was to evaluate the effects of supplementing grape pomace (GP) in lambs’ diets. A total of 30 lambs homogeneous for body weight (13.1 ± 2.1 kg) and age (25–30 days) were randomly allocated into two groups. The control group (CTR) received a standard diet for 45 days, while in the same period the experimental group (GP+) was fed with a diet containing 10% GP on a dry matter (DM) basis. The meat samples from the two groups showed no significant differences in drip loss, cooking loss, meat color and total lipid amount. However, the experimental feeding strategy influenced the meat fatty acid composition, with an increase in the relative percentages of stearic, vaccenic and rumenic acids. In particular, the increase in rumenic acids is associated with several health benefits attributed to its high bioactive properties. In cooked meat samples stored for 5 days at 4 °C, the dietary GP supplementation induced an increase in nonanal and 1-octen-3-ol and a significant reduction of hexanal, an indicator of oxidation; this improved resistance to oxidation in the GP+ samples and was also confirmed by the thiobarbituric acid reactive species (TBARS) test. In summary, the present study showed that the dietary GP supplementation was effective in improving the fatty acid composition and the oxidative stability of lamb meat. The use and valorization of the GP as a matrix of interest for zootechnical nutrition can, therefore, represent a suitable strategy for improving the qualitative aspects of animal production.

Combinations of Beauveria bassiana and spinetoram for the management of four important stored-product pests: laboratory and field trials

The current study examines the efficacy of the semi-synthetic insecticide spinetoram and entomopathogenic fungi Beauveria bassiana (Balsamo-Crivelli) Vuillemin (Hypocreales: Cordycipitaceae) as wheat protectants against the lesser grain borer, Rhyzopertha dominica (F.) (Coleoptera: Bostrychidae), the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), the granary weevil, Sitophilus granarius (L.) (Coleoptera: Curculionidae), and the khapra beetle, Trogoderma granarium Everts (Coleoptera: Dermestidae), under laboratory and field trials. One dose of B. bassiana, i.e., 1 × 107 conidia/kg wheat, two doses of spinetoram, i.e., spine1: 0.05 ppm (mg/kg wheat), spine2: 0.1 ppm, and their combinations (Bb + spine1, Bb + spine2) were evaluated at 20, 25, and 30 °C. All treatments provided significantly higher mortality at 30 °C compared with the other two temperatures. Maximum mortality levels were observed in the treatments where B. bassiana was combined with the higher dose of spinetoram (0.1 ppm). All treatments reduced progeny production in comparison with the control groups. Maximum progeny reduction was observed at 30 °C, on wheat treated with the Bb + spine2 combination. The combination Bb + spine2 also provided elevated mortality rates in both laboratory and field persistence trials, but at 180 days caused moderate mortality to all tested insect species. Concerning progeny, at laboratory persistence trials, the combination Bb + spine2 exhibited the lowest offspring emergence to all tested species compared to the other treatments and control. Overall, our study showed that R. dominica was the most susceptible species followed by S. granarius, T. castaneum, and T. granarium. Our findings revealed that the combination of B. bassiana and spinetoram may be a useful tool for efficient and advanced integrated pest management strategies for long storage periods under multiple temperatures.

Organophosphorus pesticides in southeastern China marginal seas: Land-based export and ocean currents redistribution

Organophosphorus pesticides (OPPs) have raised an increasing public concern due to their harmful impacts. To explore the occurrence and distribution of OPPs in southeastern China marginal seas (SCMS), a sampling campaign was carried out from East China Sea (ECS) to South China Sea (SCS). A total of 33 OPPs are quantified with the ΣOPPs concentrations ranging from 4.73 to 14.15 ng/L. Higher ΣOPPs concentrations in the surface seawater from the estuaries of Yangtze River, Minjiang River, and Pearl River than those at other sampling sites indicates that riverine emissions are the principal sources of OPPs in SCMS. Different compositions of OPPs in ECS and SCS highlight the different priority of use categories for OPPs in China coastal region. In addition, the vertical diffusion and upwelling ocean currents play critical roles in the redistribution of OPPs in SCMS. For the first time, the ΣOPPs mass inventories in surface seawater of ECS and SCS are estimated at 8.51 and 11.26 t, respectively. Although the current ecological risk of OPPs is at low level in surface seawater of SCMS, the long-term use and bio-accumulative potential point to the necessity for the normalized monitoring of OPPs in China.

Chemical Composition and Insecticidal Activity against Tribolium Castaneum of Thapsia garganica L. Seed Essential Oil

Due to the several side effects of synthetic pesticides, including environmental pollution, threats to human health, and the development of pest resistance to insecticides, the use of alternative healthy, available and efficient agents in pest management strategies is necessary. Recently, the use of essential oil obtained from aromatic plants has shown significant potential for insect pest management. For this reason, the essential oil isolated from seeds of Thapsia garganica L. was investigated for the first time for its chemical profile, and its toxicity and repellency effects against Tribolium castaneum adults. Qualitative and quantitative analyses of the chemical composition by gas chromatography coupled to mass spectrometry (GC/MS) revealed the presence of 18 organic volatiles representing 96.8 % of the total constituents. The main compounds were 1,4-dimethylazulene (51.3 %) followed by methyl palmitate (8.2 %), methyl linoleate (6.2 %) and costol (5.1 %). Concerning the repellent effect, results revealed that SEO (Seed Essential Oil) was very repellent towards T. castaneum adults, with 100 % repellency after 2 h of exposure. Furthermore, the essential oil exhibited remarkable contact toxicity against T. castaneum (93.3 % of mortality) at the concentration of 10 % (v/v). The median lethal dose (LD50 ) of the topical application of the seed essential oil was 4.4 %. These encouraging outcomes suggested that the essential oil from T. garganica seeds could be considered a potent natural alternative to residual persistent and toxic insecticides.

Isolation and Identification of Volatile Substances with Attractive Effects on Wohlfahrtia magnifica from Vagina of Bactrian Camel

Vaginal myiasis is one of the most serious parasitic diseases in Bactrian camels. At present, there are no reports on biological control measures of the disease. In this paper, the metabolomic analysis of vaginal secretions from susceptible and non-susceptible camels was performed by ACQUITY UPLC H-Class Ultra Performance Liquid Chromatograph. The results matched in 140 vaginal compounds. Methylheptenone, 1-octen-3-ol, and propyl butyrate and their mixtures were selected for gas chromatography-electroantennography (GC-EAD), electroantennography (EAG), behavioral experiments and trapping experiments of Wohlfahrtia magnifica (W. magnifica). Results showed that the W. magnifica had EAG responses to the three compounds, respectively. The EAG responses of female flies to different concentrations of methylheptenone were significantly different, but to the others had no significant difference, and there was no significant difference in the same compounds between the different sexes. Behavioral and trapping experiments showed that methylheptenone and 1-octen-3-ol have significant attraction to W. magnifica, but there was no significant difference to propyl butyrate. When methylheptenone and 1-octen-3-ol were mixed in different proportions, it was found that a mixture at the ratio of 1:1 and 0.5:1 had extremely significant and significant attraction, respectively, to both male and female W. magnifica. The study showed that, except for propyl butyrate, the higher the concentrations of the other two compounds, the stronger the attractivity to the W. magnifica, and a mixture at the ratio of 1:1 could enhance the attractivity to the W. magnifica.

Antifungal Activity of Benzoquinones Produced by Tribolium castaneum in Maize-Associated Fungi

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.

Chemical cues in disease recognition and their immunomodulatory role in insects

Preventing infections is crucial for host fitness and many insects modify their behaviour upon sensing a contagion. We review chemical cues that mediate insect behaviour in response to parasites, and diseased or dead conspecifics. Considering the large diversity of behavioural disease defences described, surprisingly little is known about disease-associated cues that mediate them, especially their chemoreceptor and neuronal details. Interestingly, disease cues do not only modify host behaviour, but they could also play a direct role in immune system activation via neuroendocrine regulation, bypassing the need for risky immunological contact with the parasite. Such crosstalk is an exciting emerging research area in insect ecological immunology that should prove invaluable in studying host-parasite interactions by combining analytical methods from chemical ecology.

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.

Evaluation of Oxidation Process by Ozonation and Glucose Oxidase Enzyme on the Degradation of Benzoquinone in Wheat Flour

Background:

Wheat flour is an important food ingredient for humans, which is the basic ingredient of bread and other bakery products.

Objective:

This study aimed to assess the effect of adding Glucose Oxidase (GOX), and exposure to ozone gas on methyl-1, 4-benzoquinone (MBQ), and ethyl-1, 4-benzoquinone (EBQ) secreted by Tribolium castaneum in flour.

Methods:

The flour contaminated by MBQ and EBQ was treated with ozone gas at (10, 20, and 40 ppm) with exposure times (15, 30, and 45 min). Similarly, GOX was added to flour at (10, 15, and 20 ppm), leaving the dough for periods between 10 and 45 min after treatments. The MBQ and EBQ determined by HPLC, and the UV-Visible Spectrophotometer and Fourier Transform Infrared Spectroscopy (FTIR) were used to describe the changes that occurred in the main structure of EBQ after ozonation at 40 ppm for 45 min.

Results:

The results indicated that adding GOX enzyme to the flour at level 20 ppm degrade the MBQ to 13.7, 20.23, and 39.6 after 15, 30, and 45 min from mixing time, respectively. On the other hnad, the EBQ degrades to 13.6, 18.9, and 35.9%. In contrast, the percentages of degradation of MBQ and EBQ increases after ozonation at 40 ppm for 45min were 84.1 and 78.8%, respectively. The results obtained by UV–vis spectroscopy and FTIR reflect that many oxidation products formed as aldehydes, ketones, and carboxylic acids.

Conclusion:

In general, ozonation was a reliable treatment for the degradation of benzoquinone in flour.

Residual behavior of the potential grain fumigant 1-octen-3-ol in wheat during fumigation and ventilation processes

BACKGROUND

Our previous works indicated that 1-octen-3-ol has promising potential as an alternative grain fumigant. However, aside from its insecticidal efficacy, the presence of 1-octen-3-ol residues in grains must be investigated to assess its food safety profile.

RESULTS

A convenient and sensitive QuEChERS based GC-MS/MS method was developed to detect residues of 1-octen-3-ol in wheat. The sample pretreatment procedures were optimized. The developed method showed good linearity (R²  = 0.9999) and negligible matrix effects. The limit of detection (LOD) and limit of quantification (LOQ) for 1-octen-3-ol were 0.003 and 0.01 mg kg^-1 , respectively. Recoveries at spiked concentration levels of 0.01, 0.5, 10, 100 and 200 mg kg^-1 ranged from 90.8% to 112.4%, with relative standard deviations (RSDs, n = 5) ranged from 1.2 to 7.5%. In the fumigation process during wheat storage, there were positive correlations between the accumulation rate and fumigation concentration as well as between the accumulation amounts and fumigation time. In the ventilation process, temperature significantly affected the dissipation dynamics of 1-octen-3-ol in wheat, and the t_1/2 values at ventilation temperatures of 30 and 5 °C for 0.1 μL mL^-1 were 0.16 and 21.80 days, respectively, representing a 136-fold difference.

CONCLUSION

Preservers can regulate the ventilation temperature to achieve different goals, with either a long duration period for long-term storage or rapid dissipation for quick food consumption. This study provides guidance on the reasonable usage of 1-octen-3-ol on wheat and other stored grains. © 2021 Society of Chemical Industry.

Developing a Hazomalania voyronii Essential Oil Nanoemulsion for the Eco-Friendly Management of Tribolium confusum, Tribolium castaneum and Tenebrio molitor Larvae and Adults on Stored Wheat

Most insecticides commonly used in storage facilities are synthetic, an issue that generates concerns about food safety and public health. Therefore, the development of eco-friendly pest management tools is urgently needed. In the present study, a 6% (w/w) Hazomalania voyronii essential oil-based nanoemulsion (HvNE) was developed and evaluated for managing Tribolium confusum, T. castaneum, and Tenebrio molitor, as an eco-friendly wheat protectant. Larval and adult mortality was evaluated after 4, 8, and 16 h, and 1, 2, 3, 4, 5, 6, and 7 days, testing two HvNE concentrations (500 ppm and 1000 ppm). T. confusum and T. castaneum adults and T. molitor larvae were tolerant to both concentrations of the HvNE, reaching 13.0%, 18.7%, and 10.3% mortality, respectively, at 1000 ppm after 7 days of exposure. However, testing HvNE at 1000 ppm, the mortality of T. confusum and T. castaneum larvae and T. molitor adults 7 days post-exposure reached 92.1%, 97.4%, and 100.0%, respectively. Overall, the HvNE can be considered as an effective adulticide or larvicide, depending on the target species. Our results highlight the potential of H. voyronii essential oil for developing green nanoinsecticides to be used in real-world conditions against key stored-product pests.