Search

• We developed two sub-models that are based on varying sequence distributions. • The classification framework used one-hot encoding as input, comprising a CNN, a flattening layer, and three dense layers. • Five-fold cross-validation and independent test datasets revealed the superiority of our model. RNA interference (RNAi) has been widely utilized to investigate gene functions and has significant potential for control of pest insects. However, recent studies have revealed that the target insect species, dsRNA molecule length, target genes, and other experimental factors can affect the efficiency of RNAi mediated control, restricting the further development and application of this technology. Therefore, the aim of this study was to establish a deep learning model using bioinformatics to help researchers identify dsRNA fragments with the highest RNAi efficiency. In this study, we optimized an existing model, namely, dsRNAPredictor, by designing sub-models based on different sequence lengths. Accordingly, the data were divided into two groups: 130–399 bp and 400–616 bp long sequences. Then, one-hot encoding was employed to extract sequence information. The convolutional neural network framework comprising three convolutional layers, three average pooling layers, a flattened layer, and three dense layers was employed as the classifier. By adjusting the parameters, we established two sub-models for different sequence distributions. Using multiple independent test datasets and conducting hypothesis testing, we demonstrated that our model exhibits superior performance and strong robustness to dsRNAPredictor, respectively. Therefore, our model may help design dsRNAs with pre-screening potential and facilitate further research and applications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Long‐lasting insecticide‐incorporated netting (LLIN) has been used to deliver contact insecticides as an integrated pest management tool for stored product insect pests in food facilities. Although the presence of food is known to improve insect recovery after exposure, it is not clear whether food nutritional quality plays a role. Here, the red flour beetle Tribolium castaneum adults were exposed to two commercially available LLINs, Carifend (active ingredient α‐cypermethrin) and D‐Terrence (deltamethrin), then transferred to Petri dishes with foods with varying nutritional quality (e.g., 0–100% ratios of flour to non‐nutritive cellulose). We investigated the effects of nutrition, LLIN type, and exposure time on post‐exposure recovery, mortality, and mobility. RESULTS: After exposure for 2–168 h, the immediate mortality of T. castaneum adults ranged from 0.5% to 91.0% with Carifend and 0% to 75.3% with D‐Terrence. Adult recovery and delayed mortality were significantly affected by nutritional quality, LLIN type, exposure time, and recovery time. For both LLINs, adult recovery increased over time, with a trend for higher recovery and lower mortality with increasing nutritional quality and decreasing exposure time. In addition, adult mobility decreased multiple‐fold after Carifend or D‐Terrence exposure for 30, 60 or 90 min compared to 10 min. CONCLUSION: This study shows nutrition significantly modulates the efficacy of LLIN against T. castaneum, and thus strengthens the rationale for implementing stringent sanitation protocols for food facility managers. © 2024 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

Considering millets as climate-resilient crops and recognizing the greater need for nutritional security, cultivation and consumption of millets are being encouraged globally. Studies were conducted to understand the vulnerability of stored millets to different grain insects such as lesser grain borer Rhyzopertha dominica (Fab.), red flour beetle Tribolium castaneum (Herbst), and Angoumois grain moth Sitotroga cerealella (Oliv.) under free-choice as well as no-choice conditions at Post Harvest Technology Centre, Bapatla, Andhra Pradesh, India. Red flour beetles could multiply in significantly higher numbers in pearl millet flour in both free-choice and no-choice conditions (413.33 and 340.67 adults, respectively) followed by foxtail millet (276.0 adults) and sorghum (299.33 adults), respectively. Pearl millet was the most preferred by lesser grain borer with as many as 133.67 insects moving into the grain followed by sorghum (95.33 adults) under free-choice conditions. A mean total of 316.67 grain moths emerged from proso millet under free-choice conditions. On the other hand, finger millet and little millet were not preferred and resulted in emergence of very few moths (0.33 and 3.67 moths, respectively). Little millet and finger millet grains were less susceptible to both coleopteran and lepidopteran insects. Millet grains were analyzed for the physical parameters such as grain moisture, 1000-grain weight, grain volume, hardness, porosity, and the biochemical constituents such as protein, carbohydrates, total phenols, and tannins to understand their influence on insect preferences. Though significant correlations could not be drawn between the progeny development of insects and the physicochemical characteristics of grains, little millet and foxtail millet were found to be less preferred particularly by the internal feeders due to their smaller grain size. Pearl millet possessed higher amounts of sugars and proteins compared to other millets which might have contributed to insect preference. [ABSTRACT FROM AUTHOR]

The use of synthetic pesticides carries a significant risk of pests developing resistance, leading to decreased pesticide effectiveness. ATP‐binding cassette (ABC) transporters, especially the ABCC subfamily members, have been suggested to act as efflux pumps for various pesticides, thereby contributing to pesticide resistance. So far, the identification of potential pesticide substrates of insect ABC transporters is most often based on the quantification of transcript in arthropods. Here, we screened and identified the potential pesticide substrates of ABCC‐9C from Tribolium castaneum based on an in vitro ATPase activity assay. Together with affinity evaluation‐, cytotoxicity analysis‐, and RNA interference‐based bioactivity tests, we revealed that the insecticides, carbofuran, and buprofezin, are potential substrates of TcABCC‐9C. Additionally, we identified an amphipathic translocation channel in the transmembrane domain of TcABCC‐9C formed by 8 transmembrane helices. Molecular docking suggested that both carbofuran and buprofezin bind at the same site within the translocation channel via hydrophobic interactions. These findings indicate that TcABCC‐9C might play a critical role in multi‐pesticide resistance, providing a potential target for managing pesticide resistance and laying the groundwork for future pest control strategies. Given the conservations among ABCC subfamily members, the experimental model we developed in this study can be also applied to identify the potential substrates of other ABCC transporters, as well as to predict insecticide resistance mediated by ABCC transporters. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) technology is widely used in the biological prevention and control of terrestrial insects. One of the main factors with the application of RNAi in insects is the difference in RNAi efficiency, which may vary not only in different insects, but also in different genes of the same insect, and even in different double-stranded RNAs (dsRNAs) of the same gene. This work focuses on the last question and establishes a bioinformatics software that can help researchers screen for the most efficient dsRNA targeting target genes. Among insects, the red flour beetle (Tribolium castaneum) is known to be one of the most sensitive to RNAi. From iBeetle-Base, we extracted 12 027 efficient dsRNA sequences with a lethality rate of ≥20% or with experimentation-induced phenotypic changes and processed these data to correspond to specific silence efficiency. Based on the first complied novel benchmark dataset, we specifically designed a deep neural network to identify and characterize efficient dsRNA for RNAi in insects. The dna2vec word embedding model was trained to extract distributed feature representations, and three powerful modules, namely convolutional neural network, bidirectional long short-term memory network, and self-attention mechanism, were integrated to form our predictor model to characterize the extracted dsRNAs and their silencing efficiencies for T. castaneum. Our model dsRNAPredictor showed reliable performance in multiple independent tests based on different species, including both T. castaneum and Aedes aegypti. This indicates that dsRNAPredictor can facilitate prescreening for designing high-efficiency dsRNA targeting target genes of insects in advance. [ABSTRACT FROM AUTHOR]

Simple Summary: This study investigates how storage systems, insect pest infestations, and environmental conditions impact aflatoxin contamination and peanut quality in the southeastern United States. It aims to identify key factors affecting the deterioration of peanut quality and aflatoxin levels in commonly utilized storage facilities for in-shell peanuts. The results indicated that peanuts stored in conventional metal warehouses had higher temperatures and moisture content, leading to increased insect infestations, and aflatoxin contamination compared to those stored in flat storage facilities. A significant correlation was found between elevated temperatures, equilibrium moisture content, and the proliferation of insect pests, which contributed to considerable quality degradation. The findings underscore the critical importance of maintaining optimal storage conditions in storage facilities to preserve peanut quality and prevent aflatoxin contamination, with implications for reducing economic losses and safeguarding public health from aflatoxin exposure. Effective postharvest management is crucial for the U.S. peanut industry, given the humid-subtropical climate that promotes insect pests, Aspergillus mold, and aflatoxin contamination in peanut-producing states. This study surveyed five conventional metal warehouses (CMWs) and thirteen flat storage facilities (FSFs) in northeastern, southeastern, and southwestern Georgia, USA, from December 2022 to July 2023. Peanuts were sampled monthly to assess the temporal abundance and diversity of storage insect pests, damage variables, and aflatoxin levels in farmers' stock peanuts. A monoclonal antibody-based affinity chromatographic assay determined the total aflatoxin levels in samples. The most common insect species, accounting for ~85.73 of the total captured, included Cryptolestes ferrugineus, Tribolium castaneum, Ahasverus advena, Plodia interpunctella, Cadra cautella, Ephestia elutella, Liposcelis spp., and Lachesilla pedicularia. Insect populations peaked in June and July, with similar diversity trends across CMWs and FSFs. Insect-damaged kernels, weight loss, discolored kernels, loose-shelled kernels, moisture content, and aflatoxin levels ranged from 3.02 to 11.45%, 1.11 to 3.60%, 2.11 to 11.20%, 1.56 to 4.91%, 6.89 to 8.85%, and 0.43 to 27.59 ppb, respectively. The high prevalence of insect pests, their damage capabilities, and the aflatoxin levels of infested peanuts highlight the need for an improved IPM strategy in warehouses to ensure safe and sustainable peanut storage in the USA. [ABSTRACT FROM AUTHOR]

Dispersal is an important behavior in many animals, with profound effects on individual fitness and the evolutionary trajectories of populations. This is especially true within taxa with particular life-history strategies, for example those that exploit ephemeral habitat. Further, dispersal is commonly seen to be part of behavioral syndromes - suites of traits that covary across behavioral contexts. The red flour beetle, Tribolium castaneum (Coleoptera, Tenebrionidae), is a major post-harvest crop pest responsible for large losses through the infestation of stored grain. In this system dispersal is known to have a strong genetic basis and differential artificial selection on dispersal traits produces strong phenotypic divergence. However, it is unknown which traits are able to rapidly evolve to produce these results, or which behavioral components underlie differences in dispersal. Using replicate lines of T. castaneum previously selected for divergent dispersal behavior, we test for correlated activity and movement patterns, morphology and substrate surface use. We find robustly repeatable associations between the dispersal phenotype and higher activity, straighter paths, larger body size (but not relative leg length) and increased tendency to remain at the surface of fodder. Together our results suggest that dispersal is part of a syndrome of traits in T. castaneum, and must be treated as such when considering the evolution of dispersal in this system, and in attempting to predict and control its spread. [ABSTRACT FROM AUTHOR]

Climate change is increasing mean temperatures, and intensifying heatwaves. Natural populations may respond to stress through shorter-term acclimation via plasticity and/or longer-term inter-generational evolution. However, if the pace and/or extent of thermal change is too great, local extinctions occur; one potential cause in ectotherms is identified to be the heat-liability of male reproductive biology. Recent data from several species, including the beetle Tribolium castaneum , confirmed that male reproductive biology is vulnerable to heatwaves, which may constrain populations. However, such reproductive-damage may be overestimated, if there is potential to adapt to elevated mean temperatures associated with climate change via evolution and/or acclimation. Here, we tested this to evaluate whether pre-exposures could improve heatwave tolerance (adaptation or acclimation), by experimentally evolving Tribolium castaneum populations to divergent thermal regimes (30 °C vs. 38 °C). Findings across assays revealed that relative to 30 °C-regime males, males from the 38 °C regime, maintained constantly at 8 °C warmer for 25 generations, displayed an increase; (i) in post heatwave (42 °C) reproductive fitness by 55%, (ii) survival by 33%, and (iii) 32% larger testes volumes. Unexpectedly, in the acclimation assay, warm-adapted males' post-heatwave survival and reproduction were best if they experienced cool developmental acclimation beforehand, suggesting a cost to adapting to 38 °C. These results help progress knowledge of the potential for survival and reproduction to adapt to climate change; trait specific adaptation to divergent thermal regimes can occur over relatively few generations, but this capacity depended on the interaction of evolutionary and thermal acclimatory processes. [ABSTRACT FROM AUTHOR]

The caloric content and macronutrient ratio of diet consumed is a major source of phenotypic variation in most animal populations. While these nutritional effects have been well-documented for a variety of life-history and morphological traits, the effects of nutrition on male genitals are poorly understood but genitals are thought to be more canalised than general morphology and hence less susceptible to variation in nutrition. Even less is known about the effects of nutrition on female genital form, which to our knowledge, have never been investigated. Here we tested for effects of juvenile dietary macronutrients (protein and carbohydrate) on larval survival, adult morphology, including genital size and shape in male and female flour beetles (Tribolium castaneum). We found there was nutritionally induced plasticity in larval survival and morphology, although the latter effect was variable, with body size being most responsive to dietary macronutrients and genital size and shape being least responsive. Functionally equivalent morphological traits in the sexes responded similarly to nutrition. Previously, we showed that the genitalia of male and female T. castaneum are subject to strong stabilising sexual selection, and our current findings suggest that developmental mechanisms reduce the nutritional sensitivity of male and female genitals, possibly to ensure matching during mating. [ABSTRACT FROM AUTHOR]

Food grains were severely damaged by stored goods insects. The red flour beetle Tribolium castaneum, the cigarette beetle Lasioderma serricorne and the rice weevil Sitophilus orysae are some of the most destructive pests which attack raw cereals throughout the world. In stored grain mill, fumigation with synthetic fumigants was the most economical tool for managing stored pests. Nevertheless, the application of chemical pesticides caused adverse effects on humans and environment. Chloroform, acetone, methanol and water extracts and essential oil of Haplophyllum tuberculatum aerial parts were tested for their fumigant and repellent effect against adults of the three stored products pests (T. castaneum, L. serricorne and S. oryzae). GC/MS analysis of the essential oil resulted in determination of 19 compounds. The major constituents were β-phellandrene (16.17%), trans-p-menth-2-ene-1-ol, (13.22%) and cis-p-menth-2-ene-1-ol (8.29%). Thus, it seemed that the essential oil had the highest fumigant activity against L. serricorne after 12 h of exposure compared to the two other insects with a LC50 equal to 38.59 µ.l-1 air. The best repellency was observed for the chloroform and methanol extracts against T. castaneum. The respective repellent doses RD50 values were = 0.03 and 0.04 mg.ml-1 after 24 h of exposure. However, after 24 h of exposure acetone extract seems to be more repellent with respective repellent dose values of = 0.14 mg.ml-1 (RD50) against L. serricorne. H. tuberculatum essential oil and extract proved to be effective in control pest infestations in grains and dry food products. [ABSTRACT FROM AUTHOR]

RNA interference (RNAi) has emerged as an eco‐friendly alternative to classic pesticides for pest control. This review highlights the importance of identifying the best target genes for RNAi‐mediated pest control. We argue that the knowledge‐based approach to predicting effective targets is limited by our current gaps of knowledge, making unbiased screening a superior method for discovering the best target processes and genes. We emphasize the recent evidence that suggests targeting conserved basic cellular processes, such as protein degradation and translation, is more effective than targeting the classic pesticide target processes. We support these claims by comparing the efficacy of previously reported RNAi target genes and classic insecticide targets with data from our genome‐wide RNAi screen in the red flour beetle, Tribolium castaneum. Finally, we provide practical advice for identifying excellent target genes in other pests, where large‐scale RNAi screenings are typically challenging. [ABSTRACT FROM AUTHOR]

ABSTRACT Arthropods have integrated digestive and renal systems, which function to acquire and maintain homeostatically the substances they require for survival. The cryptonephridial complex (CNC) is an evolutionary novelty in which the renal organs and gut have been dramatically reorganised. Parts of the renal or Malpighian tubules (MpTs) form a close association with the surface of the rectum, and are surrounded by a novel tissue, the perinephric membrane, which acts to insulate the system from the haemolymph and thus allows tight regulation of ions and water into and out of the CNC. The CNC can reclaim water and solutes from the rectal contents and recycle these back into the haemolymph. Fluid flow in the MpTs runs counter to flow within the rectum. It is this countercurrent arrangement that underpins its powerful recycling capabilities, and represents one of the most efficient water conservation mechanisms in nature. CNCs appear to have evolved multiple times, and are present in some of the largest and most evolutionarily successful insect groups including the larvae of most Lepidoptera and in a major beetle lineage (Cucujiformia + Bostrichoidea), suggesting that the CNC is an important adaptation. Here we review the knowledge of this remarkable organ system gained over the past 200 years. We first focus on the CNCs of tenebrionid beetles, for which we have an in‐depth understanding from physiological, structural and ultrastructural studies (primarily in Tenebrio molitor), which are now being extended by studies in Tribolium castaneum enabled by advances in molecular and microscopy approaches established for this species. These recent studies are beginning to illuminate CNC development, physiology and endocrine control. We then take a broader view of arthropod CNCs, phylogenetically mapping their reported occurrence to assess their distribution and likely evolutionary origins. We explore CNCs from an ecological viewpoint, put forward evidence that CNCs may primarily be adaptations for facing the challenges of larval life, and argue that their loss in many aquatic species could point to a primary function in conserving water in terrestrial species. Finally, by considering the functions of renal and digestive epithelia in insects lacking CNCs, as well as the typical architecture of these organs in relation to one another, we propose that ancestral features of these organs predispose them for the evolution of CNCs. [ABSTRACT FROM AUTHOR]

Tenebrionid beetles have been highly successful in colonising environments where water is scarce, underpinned by their unique osmoregulatory adaptations. These include a cryptonephridial arrangement of their organs, in which part of their renal/Malpighian tubules are bound to the surface of the rectum. Within the cryptonephridial tubules, an unusual cell type, the leptophragmata, plays a key physiological role underpinning water conservation. Nothing was known about the developmentalmechanisms or evolution of these unusual renal cells. Here, we investigate mechanisms underpinning leptophragmata development in Tribolium castaneum. We find that leptophragmata express and require the Tiptop transcription factor, similar to secondary renal cells in Drosophila melanogaster, which express Teashirt and Tiptop, despite Drosophila lacking a crypronephridial arrangement. An additional transcription factor, Dachshund, is required to establish leptophragmata identity and to distinguish them from the secondary cells in the non-cryptonephridial region of renal tubule of Tribolium. Dachshund is also expressed in a sub-population of secondary cells in Drosophila. Leptophragmata, which are unique to the beetle lineage, appear to have originated froma specific renal cell type present ancestrally and to be specified by a conserved repertoire of transcription factors. [ABSTRACT FROM AUTHOR]

In the pursuit of conducting a systematic investigation on the bioactivity of the family Alpinia, and searching for bioactive natural products to minimize the risks of synthetic pesticides, the Alpinia blepharocalyx K. Schum, Alpinia oxyphylla Miq. and Alpinia zerumbet × A. henryi 'Red Harvest' were selected as objects. The essential oils (EOs) of the three Alpinia were obtained by hydrodistillation and analyzed for chemical composition, evaluated for bioactivity toward the adults of Tribolium castaneum, Lasioderma serricorne and Liposcelis bostrychophila. A total of thirty-six components were identified in the extracted EOs, mainly composed of monoterpene hydrocarbons (0-91.75%) and oxygenated monoterpenes (0-57.82%). GC-MS profiling displayed perillal, ѱ-limonene, 1,8-cineole and β-pinene as major contributors to EOs area percentage but quantitative variations were observed with variability in the five EOs. The EO of A. zerumbet × A. henryi 'Red Harvest' fruit (EOAZHF) possessed the strongest contact toxicity against T. castaneum and L. bostrychophila, with the LD50 value of 14.02 μg/adult and the LC50 value of 48.64 μg/cm2, respectively. While the EO of A. oxyphylla rhizome (EOAOR) exhibited the highest contact toxicity to L. serricorne (LD50 = 8.06 μg/ adult). Upon repellence, all of the extracted EOs exhibited repellent activity, but the repellency gradually decreased with the decrease of concentration, and the target insects showed different sensitivities to the EOs. The results demonstrated that the EOs of the three Alpinia have high variability in composition and have the potential for the control of stored-product insects. [ABSTRACT FROM AUTHOR]

Simple Summary: The red flour beetle is the most destructive pest of stored grain commodities, including flour, food grains, biscuits, pasta, nuts, cereals, and beans. Warehouse owners mostly use fumigants to control its infestation; however, these fumigants are toxic. The Indo–Pakistan region is rich in certain plant species that have repellent or deterrent effects on insects, and these plants are safer for humans. Among these plants are Mexican tea, long leaf Indian pine, rattan pepper, garden cress, neem, Baccharis teindalensis (a Columbian native herb also found in Pakistan), and marjoram. Hence, in the present study, we determined the toxic effect of these essential oil extracts against red flour beetle. The toxicity and repellent activities of these plant oils were determined through four-arm olfactometer bioassays. Mortality was recorded 1 day, 2 days, and 3 days after oil extract exposure. Data were analyzed using statistical software. Means were compared through LSD at the 5% level of significance. Overall, Mexican tea and Indian native palm oil were effective repellents. This study concludes that Mexican tea and Indian native palm oil can be used as alternative repellents against red flour beetle infestation. Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) is the most destructive pest of stored grain commodities. To control the attack of this insect pest, it is important to develop non-hazardous alternatives to replace fumigants. This study examined the fumigant toxicity and repellent activity of seven essential oils (Chinopodium ambrosiodes, Pinus roxburghii, Zanthoxylum armatum, Lepidium sativum, Azadirachta indica, Baccharis teindalensis, and Origanum majorana) against adult T. castaneum under controlled laboratory conditions. The fumigant toxicity and repellent activities of essential oils were tested using five different doses (62.5, 125, 250, 500, and 1000 µg) in vapour-phase fumigation and four-arm olfactometer bioassays, respectively. In vapor-phase fumigation bioassays, mortality data were recorded after 24, 48, and 72 h. The results showed that C. ambrosiodes and P. roxburghii essential oils are potential fumigants against adult T. castaneum. In repellency bioassays, a one-week-old adult population of T. castaneum was used to test the repellency potential of the essential oils. The results indicated that C. ambrosiodes and P. roxburghii had significant repellency potential against T. castaneum. Overall, we conclude that these essential oils have strong repellent and fumigant properties and can be used as potential repellent compounds to deter the insects. [ABSTRACT FROM AUTHOR]

The repellent activity of two odourless vegetable oils (sweet almond—SAO and soybean—SO) applied on filter paper and four types of food packaging materials (polyethylene film, plastic gunnysacks, cardboard, and wood) was tested against three species of stored product pests (Sitophilus granarius, Tribolium castaneum, and Oryzaephilus surinamensis). The repellence of three doses was evaluated after 24 h, and after 7, 14, 21, and 28 days. Both oils exhibited a repellent effect when applied to filter paper, but this effect decreased with time and concentration. The most susceptible species was T. castaneum. The maximum repellence was 84% and 76% for SO and SAO, respectively. On packaging materials, the repellent effect diminished after a certain period of time, ranging from 7 to 28 days. Subsequently, the oils even became attractive. Generally, the repellent effects of both SO and SAO were higher on cardboard and wood slab than on polyethylene film and plastic gunnysacks. As such, in the case of SO, the repellence against T. castaneum was 88% 24 h after application on cardboard, whilst 68% on plastic bag. This work demonstrated the repellent potential of vegetable oils in the short term for the protection of packaged food against stored product pests. [ABSTRACT FROM AUTHOR]

This study investigated chemical compositions and biocidal activities from the aerial parts of Rhododendron thymifolium against Tribolium castaneum, Lasioderma serricorne, and Ditylenchus destructor. In total, 13 components were isolated from the aerial parts of R. thymifolium by chromatographic separation techniques. Based on the results of MS, 1H NMR, and 13C NMR spectrometry, their structures were determined as ent-kaurane-16β-ol (1), pentacosane (2), undecanoic acid, ethyl ester (3), 1-Tridecanethiol (4), 1-Dodecanol (5), 4-Methyl-7-hydroxycoumarin (6), tertradecan-1-ol (7), apocynin (8), 3-Methoxy-4-methylbenzaldehyde (9), scopoletin (10), hyperin (11), quercetin (12), acetophenone (13). In addition, ent-kaurane-16β-ol (1) was isolated from R. thymifolium for the first time. Then, the insecticidal toxicities against T. castaneum, L. serricorne, and D. destructor. of compounds 1–13 were evaluated, and the results showed that apocynin (8) and acetophenone (13) exhibited obvious contact activity against the storage pests with LD50 values of 6.46 and 8.72 μg/adult respectively. Acetophenone (13) showed excellent contact activity against D. destructor with LC50 values of 0.08 mg/mL. The study clearly showed the active fractions from R. thymifolium have might potential to be developed into potential compounds on storage insect prevention. [ABSTRACT FROM AUTHOR]

Hemocytes are pivotal in the immune response of insects against invasive pathogens. However, our knowledge of hemocyte types and their specific function in Tribolium castaneum, an increasingly important Coleoptera model insect in various research fields, remains limited. Presently, a combination of morphological criteria and dye‐staining properties were used to characterize hemocyte types from T. castaneum larvae, and 4 distinct types were identified: granulocytes, oenocytoids, plasmatocytes and prohemocytes. Following different immune challenges, the total hemocyte counts declined rapidly in the initial phase (at 2 h), then increased over time (at 4 and 6 h) and eventually returned to the naive state by 24 h post‐injection. Notably, the morphology of granulocytes underwent dramatic changes, characterized by an expansion of the surface area and an increased production of pseudopods, and with the number of granulocytes rising significantly through mitotic division. Granulocytes and plasmatocytes, the main hemocyte types in T. castaneum larvae, can phagocytose bacteria or latex beads injected into the larval hemolymph in vivo. Furthermore, these hemocytes participate in the encapsulation and melanization processes in vitro, forming capsules to encapsulate and melanize nickel–nitrilotriacetic acid (Ni–NTA) beads. This study provides the first comprehensive characterization of circulating hemocytes in T. castaneum larvae, offering valuable insights into cell‐mediated immunity in response to bacterial infection and the injection of latex beads. These results deepen our understanding of the cellular response mechanisms in T. castaneum larvae and lay a solid foundation for subsequent investigations of the involvement of T. castaneum hemocytes in combating pathogens. [ABSTRACT FROM AUTHOR]

Circadian clocks are inherent to most organisms, including cryptozoic animals that seldom encounter direct light, and regulate their daily activity cycles. A conserved suite of clock genes underpins these rhythms. In this study, we explore the circadian behaviors of the red flour beetle Tribolium castaneum, a significant pest impacting stored grain globally. We report on how daily light and temperature cues synchronize distinct activity patterns in these beetles, characterized by reduced morning activity and increased evening activity, anticipating the respective environmental transitions. Although less robust, rhythmicity in locomotor activity is maintained in constant dark and constant light conditions. Notably, we observed more robust rhythmic behaviors in males than females with individual variation exceeding those previously reported for other insect species. RNA interference targeting the Clock gene weakened locomotor activity rhythms. Our findings demonstrate the existence of a circadian clock and of clock-controlled behaviors in T. castaneum. Furthermore, they highlight substantial individual differences in circadian activity, laying the groundwork for future research on the relevance of individual variation in circadian rhythms in an ecological and evolutionary context. [ABSTRACT FROM AUTHOR]

The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is a cosmopolitan and destructive external-infesting pest at many food facilities. The use of deltamethrin- and α-cypermethrin-incorporated long-lasting insecticide-incorporated netting (LLIN) has shown incredible promise for the management of stored product insects. However, it is unknown how LLIN deployed within food facilities may affect the long-term population dynamics of T. castaneum compared to populations where no LLIN is present. Exposure to LLIN has been shown to affect mortality in the current generation and decrease progeny production in the subsequent generation. Thus, we modeled the long-term population dynamics of T. castaneum at food facilities over 15 generations by incorporating realistic estimates for mortality and progeny reduction after contact with LLIN compared to baseline growth by the species. We parameterized the model with estimates from the literature and used a four-stage structured population (eggs, larvae, pupae, and adults). The model was implemented using the package popbio in R. Our models suggest that deploying LLIN led to significant population reductions based on the estimates of mortality and progeny reduction from prior work, whereas the baseline model exhibited exponential population growth. In addition, there were differences in the frequencies of each life stage under each scenario modeled. As a result, it appears deploying LLIN may contribute to the local extirpation of T. castaneum within as few as 15 generations. Our work contributes to a growing literature about the effectiveness of incorporating LLIN into existing pest management programs for managing stored product insects in food facilities. [ABSTRACT FROM AUTHOR]

Background: Numerous insect pests attack stored grains causing both qualitative and quantitative losses. The most damaging pest that infests dry stored produce is the red flour beetle, Tribolium castaneum, a secondary pest of stored goods. This pest, especially in its adult stage, exhibits resistance to chemical insecticides, thereby rendering the traditional pesticides ineffective in controlling it. Phyto-derivatives, which are strong insecticides and also ecologically benign, have gained interest as non-chemical solutions for controlling this pest. Hence, the objective of this study was to investigate the potential of Piper longum leaf extract insecticidal action as an environmentally benign insecticide for the first time against the adults of T. castaneum. In this study, P. longum leaf ethanol extract was tested against the adults of T. castaneum by petri dish bioassay method. Ad hoc studies to verify significant mortality for the initial confirmation of adulticidal activity were conducted for 24 h at different dosages of 62.5, 125, 250, 500 and 1000 mg/L of P. longum leaf ethanol extract. Thereafter, dosages set at 10, 20, 30 and 40 mg/L for the fractions of P. longum leaf ethanol extract were conducted. Prior to this, the leaf extract of this plant was subjected to column chromatography for fractionation. The fractions tested for adulticidal activity were subjected to gas chromatography–mass spectroscopy. Results: Significant adulticidal action with 100% adult mortality was observed in ethanol extract of P. longum leaves. Among the fourteen fractions (F0–F13) obtained tested, only fractions, F5, F10 and F13, demonstrated adulticidal activity, and the remaining fractions displayed poor activity. One hundred per cent morality was noted in T. castaneum adults after 96 h at 40 mg/L in F5 and F10, and in F13 at 20 mg/L, and their respective LD50 values were 17.6, 26.6 and 10.0 mg/L. The fractions F5, F10 and F13 contained fatty acids, viz., hexadecanoic acid, dotriacontane and heptacosane in F5; tetradecanoic acid and nonadecanoic acid in F10; and octadecanoic acid, aspartame and tridecanoic acid in F13, revealed through gas chromatography–mass spectroscopy. Conclusions: The results of the study showed that P. longum ethanol leaf extract revealed significant adulticidal activity and is a promising toxic agent to the adults of T. castaneum. The fatty acids in the ethanolic leaf extract fractions of P. longum could have caused toxicity to the adults of T. castaneum. According to the current literature survey, this is the first research report on the adulticidal activity of P. longum leaf extracts against the adults of T. castaneum. [ABSTRACT FROM AUTHOR]

The clustered regularly interspaced small palindromic repeats (CRISPR) / CRISPR‐associated nuclease 9 (Cas9)‐mediated gene editing technology has revolutionized the study of fundamental biological questions in various insects. Diverse approaches have been developed to deliver the single‐guide RNA (sgRNA) and Cas9 to the nucleus of insect embryos or oocytes to achieve gene editing, including the predominant embryonic injection methods and alternative protocols through parental ovary delivery. However, a systematic comparative study of these approaches is limited, especially within a given insect. Here, we focused on revealing the detailed differences in CRISPR/Cas9‐mediated gene editing between the embryo and ovary delivery methods in the beetle Tribolium castaneum, using the cardinal and tyrosine hydroxylase (TH) as reporter genes. We demonstrated that both genes could be efficiently edited by delivering Cas9/sgRNA ribonucleoproteins to the embryos by microinjection, leading to the mutant phenotypes and indels in the target gene sites. Next, the Cas9/sgRNA complex, coupled with a nanocarrier called Branched Amphiphilic Peptide Capsules (BAPC), were delivered to the ovaries of parental females to examine the efficacy of BAPC‐mediated gene editing. Although we observed that a small number of beetles’ progeny targeting the cardinal exhibited the expected white‐eye phenotype, unexpectedly, no target DNA indels were found following subsequent sequencing analysis. In addition, we adopted a novel approach termed “direct parental” CRISPR (DIPA‐CRISPR). However, we still failed to find gene‐editing events in the cardinal or TH gene‐targeted insects. Our results indicate that the conventional embryonic injection of CRISPR is an effective method to initiate genome editing in T. castaneum. However, it is inefficient by the parental ovary delivery approach. [ABSTRACT FROM AUTHOR]

Many animal species have movement abilities. Behavior is important for evolutionary ecology because animal movement leads to dispersal, migration, search for food and mates, and escaping from enemies. However, individual differences in movement activity are found within a population. This phenomenon can be affected by various factors, one of which is suggesting that higher moving activity has fitness cost, whereas lower moving activity has benefits. Animal movement may also affect reproduction (e.g., resource allocation tradeoff between movement and reproduction as well as intra‐ and intersexual selection). Although many previous studies have investigated the relationship between movement and reproduction, less attention has been paid to walking movement. In this study, previous studies that investigated the relationship between movement and reproduction were reviewed using the flour beetle Tribolium castaneum, a model insect in behavioral ecology and genetics. Several previous studies suggest that beetle walking is strongly associated with male and female reproductive traits. In recent years, empirical studies on the correlation between walking and other traits have increased, particularly in T. castaneum. Although this species can fly and walk, the movement is often discussed without discriminating between flight and walk. Differences in modes of movement may affect the correlation between movement and other traits; thus, discussing each mode of movement separately is necessary. [ABSTRACT FROM AUTHOR]

Tribolium castaneum is a challenging pest of stored products, causing significant economic losses. The present study explored the efficacy of Coridothymus capitatus essential oil and its primary constituent, carvacrol, as eco-friendly alternatives for managing this pest. To evaluate their insecticidal potential, repellency, fumigant toxicity, and antifeedant properties, progeny inhibition assays were performed. Carvacrol exhibited superior repellency compared to the essential oil, achieving a 92% repellency rate at 2 mg/cm2. Both compounds demonstrated significant fumigant toxicity against T. castaneum, with LC50 values of 168.47 and 106.5 μL/L for the essential oil and carvacrol, respectively, after 24 h. Carvacrol also outperformed the essential oil in antifeedant activity, inducing an 80.7% feeding deterrence at 1.17 mg/g. Moreover, both treatments effectively suppressed the development of the pest's progeny. These results collectively underscore the potent insecticidal properties of C. capitatus essential oil and carvacrol, particularly carvacrol, as promising candidates for the sustainable management of T. castaneum in stored product protection. [ABSTRACT FROM AUTHOR]

Tribolium castaneum (Herbst) and Tribolium confusum (Jacquelin du Val) are common and damaging pests of stored grain flours in several homes and flour mill industries worldwide. This study examines how food, species, concentration, and exposure time affect the susceptibility and nutritional physiology of T. castaneum and T. confusum when exposed to partially purified methanolic fruit extract of Dennettia tripetala (G. Baker) and two of its major active compounds (linalool and 2‐phenylnitroethane). Gas chromatography–mass spectrometry was used to evaluate the chemical profile of the partially purified plant extract. Thirty‐two compounds were found in the plant, including established insecticidal and insectifuge compounds such as linalool, cis‐vaccenic acid, 2‐phenylnitroethane, and linoleic acid, among others. The interactions among the factors have a differential impact on the susceptibility and nutritional indices of both Tribolium species to D. tripetala, linalool and 2‐phenylnitroethane. According to LC50 values, linalool and 2‐phenylnitroethane were the most and least toxic to both beetles, respectively. With increasing extract concentrations, all nutritional indices except feeding deterrence decreased. Relative to controls, linalool and 2‐phenylnitroethane evoked the highest and least reduction, respectively, in beetles' nutritional indices. Treated corn discs deterred both species over treated wheat discs, regardless of insecticide type. T. castaneum had a higher overall food consumption than T. confusum. Regardless of insecticide type, the relative growth rate was higher in T. confusum and T. castaneum fed with treated corn and wheat discs, respectively. D. tripetala extract, linalool, and 2‐phenylnitroethane showed higher post‐ingestion toxicity to T. castaneum than T. confusum. This study emphasises the importance of certain intrinsic factors, like beetles' species and cereal food types, when managing Tribolium species with plant‐based insecticides. The various data obtained from this study will help researchers and pesticide manufacturers formulate effective biopesticides from linalool and 2‐phenylnitroethane to control Tribolium species on corn and wheat flours. [ABSTRACT FROM AUTHOR]

This work focuses on the profiling of semiochemicals (SCS) from Callosobruchus maculatus, Sitophilus oryzae and Tribolium castaneum by headspace solid-phase microextraction (HS-SPME) coupled with gas chromatography–mass spectrometry (GC–MS) technique. Totally, 6, 9 and 8 volatile compounds (VCS) were detected from C. maculatus, S. oryzae and T. castaneum, respectively. As a result of pherobase analysis and preference bioassay, stearic acid (C. maculatus); nonanal, lauric acid and stearic acid (S. oryzae); stearic acid (T. castaneum) were identified as new SCS that could be useful for integrated pest management (IPM) practices. [ABSTRACT FROM AUTHOR]

Waprin, a WAP (Whey acidic protein) domain‐containing extracellular secretory protein, is widely known for its antibacterial properties. In this study, a waprin homologue (Tc_wapF) expressing in a female‐specific manner was identified in Tribolium castaneum, through the analysis of sex‐specific transcriptomes. Developmental‐ and tissue‐specific profiling revealed the widespread expression of Tc_wapF in adult female tissues, particularly in the ovary, gut and fatbody. This female‐specific expression of Tc_wapF is not regulated by the classical sex‐determination cascade of T. castaneum, as we fail to get any attenuation in Tc_wapF transcript levels in Tcdsx and Tctra (key players of sex determination cascade of T. castaneum) knockdown females. RNA interference‐mediated knockdown of Tc_wapF in females led to the non‐hatching of eggs laid by these females, suggesting the crucial role of Tc_wapF in the embryonic development in T. castaneum. This is the first report on the identification of a sex‐specific waprin homologue in an insect and its involvement in embryonic development. Future investigations on the functional conservation of insect waprins and their mechanistic role in embryonic development can be exploited for improving pest management strategies. [ABSTRACT FROM AUTHOR]

Circadian rhythms are self‐sustained endogenous oscillations that are found in all living organisms. In insects, circadian rhythms control a wide variety of behavioral and physiological processes, including feeding, locomotion, mating, and metabolism. While the role of circadian rhythms in adult insects is well‐understood, it is largely unexplored in larvae. This study investigates the potential for larval synchronized activity in the red flour beetle (Tribolium castaneum), a species exhibiting solitary and aggregation phases. We hypothesized that, similar to adults, larvae would exhibit a daily activity pattern governed by an endogenous circadian clock. We further predicted that the transition between the solitary and gregarious phases extends to unique temporal activity patterns. Our results revealed unique timekeeper gene expression in larvae, leading to a distinct daily rhythm characterized by nocturnal activity. Cues indicating on potential cannibalism did not change daily activity peak. However, the absence of these cues significantly reduced the proportion of rhythmic larvae and led to higher variation in peak activity, highlighting the crucial role of social interactions in shaping their rhythmicity. This study sheds light on the evolution and function of larval synchronization in group‐living insects, offering novel insights into this complex behavior. [ABSTRACT FROM AUTHOR]

Simple Summary: This study addresses global food security by highlighting the challenge of protecting food losses from insect damage. To find effective low-risk ways to manage these pests, we assessed the avoidance of the red flour beetle, a common pest in stored grains, to essential oils. Through various experiments in the laboratory, we investigated the beetles' behavioral response to different scented oils. While no definitive repellent was identified, this study sheds light on factors influencing insect behavior and the need for further research in behaviorally based management tactics such as avoidance. Ultimately, this work aims to develop strategies to protect stored grains, contributing to global food security efforts. Background: Food security is an increasingly pressing global issue, and by 2050, food production will not be sufficient to feed the growing population. Part of global food insecurity can be attributed to post-harvest losses, including quantity and quality losses caused by stored-product pests like insects. It is thus timely to find management strategies to mitigate these losses and counteract food insecurity. The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), a global stored-product pest with a wide range of food sources, was used in this study to assess repellency to a selection of essential oils. Methods: Multiple behaviorally relevant methods were used to determine the efficacy of the essential oils in assays to pinpoint the most promising repellents. Experiments were used to assess individual and group behaviors with or without airflow and examined the behavioral variation in distance moved and the time spent away from the oil. Results: It was found that exposure to essential oils and conditions of experimentation considerably influenced T. castaneum's behavioral response, but a clear candidate for repellency could not be chosen based on the collected data. Conclusions: Follow-up research is needed to pinpoint repellents for integrated pest management practices to protect grains from stored-product pests and to justify their use in and around commodities. [ABSTRACT FROM AUTHOR]

Tribolium castaneum Herbst and Rhyzopertha dominica Fabricius are significant pests causing both qualitative and quantitative deterioration of stored products. The reliance on synthetic fumigants to control these pests poses numerous risks to human health and the environment. Given cassava's status as a cyanogenic plant, this study screened nine cassava varieties to isolate insecticidal compounds effective against stored product pests. Both young and mature leaves were subjected to hydrogen cyanide extraction, a potential fumigant approved by the Central Insecticidal Board (CIB) of India. Extraction was performed using two methods: direct leaf crushing at room temperature and mechanical extraction with a biopesticide extraction plant at ICAR-Central Tuber Crops Research Institute. Among the varieties, Sree Swarna exhibited the highest cyanogen content, while Sree Jaya had the least. Laboratory assays demonstrated that R. dominica was more susceptible to the cassava-derived bio-fumigant than T. castaneum. These findings suggest that bio-fumigants from cassava leaves are a viable alternative to synthetic fumigants for managing stored product pests. [ABSTRACT FROM AUTHOR]

BACKGROUND: Actin‐related protein 2/3 complex regulates actin polymerization and the formation of branched actin networks. However, the function and evolutionary relationship of this complex subunit 2 (Arpc2) has been poorly understood in insects. RESULTS: To address these issues, we performed comprehensive analysis of Arpc2 in Tribolium castaneum. Phylogenetic analysis revealed that Arpc2 was originated from one ancestral gene in animals but evolved independently between vertebrates and insects after species differentiation. T. castaneum Arpc2 has a 906‐bp coding sequence and consists of 4 exons. Arpc2 transcripts were abundantly detected in embryos and pupae but less so in larvae and adults, while it had high expression in the gut, fat body and head but low expression in the epidermis of late‐stage larvae. Knockdown of it at the late larval stage inhibited the pupation and resulted in arrested larvae. Silencing it in 1‐day pupae impaired eclosion, which caused adult wings to fail to close. Injection of Arpc2 dsRNAs into 5‐day pupae made adults have smaller testis and ovary and could not lay eggs. The expression of vitellogenin 1 (Vg1), Vg2 and Vg receptor (VgR) was downregulated after knocking down Arpc2 5 days post‐adult emergence. Arpc2 silencing reduced 20‐hydroxyecdysone titer by affecting the enzymes of its biosynthesis and catabolism but increased juvenile biosynthesis via upregulating JHAMT3 expression. CONCLUSION: Our results indicate that Arpc2 is associated with the metamorphosis and reproduction by integrating ecdysone and juvenile hormone metabolism in T. castaneum. This study provides theoretical basis for developing Arpc2 as a potential RNA interference target for pest control. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

During animal embryogenesis, one of the earliest specification events distinguishes extraembryonic (EE) from embryonic tissue fates: the serosa in the case of the insects. While it is well established that the homeodomain transcription factor Zen1 is the critical determinant of the serosa, the subsequent realization of this tissue's identity has not been investigated. Here, we examine serosal differentiation in the beetle Tribolium castaneum based on the quantification of morphological and morphogenetic features, comparing embryos from a Tc-zen1 RNAi dilution series, where complete knockdown results in amnion-only EE tissue identity. We assess features including cell density, tissue boundary morphology, and nuclear size as dynamic readouts for progressive tissue maturation. While some features exhibit an all-or-nothing outcome, other key features show dose-dependent phenotypic responses with trait-specific thresholds. Collectively, these findings provide nuance beyond the known status of Tc-Zen1 as a selector gene for serosal tissue patterning. Overall, our approach illustrates how the analysis of tissue maturation dynamics from live imaging extends but also challenges interpretations based on gene expression data, refining our understanding of tissue identity and when it is achieved. [ABSTRACT FROM AUTHOR]

Dispersal is an important facet of the life history of many organisms and is, therefore, subject to selective pressure but does not evolve in isolation. Across nature, there are examples of dispersal syndromes and life history strategies in which suites of traits coevolve and covary with dispersal in combinations that serve to maximize fitness in a given ecological context. The red rust flour beetle, Tribolium castaneum, is a model organism and globally significant post-harvest pest that relies on dispersal to reach new patches of ephemeral habitat. Dispersal behaviour in Tribolium has a strong genetic basis. However, a robust understanding of the relationship between dispersal and other life-history components, which could elucidate evolutionary processes and allow pest managers to control their spread and reduce the impact of infestation, is currently lacking. Here, we use highly replicated lines of T. castaneum previously artificially selected for divergent small-scale dispersal propensity to robustly test several important life history components: reproductive strategy, development time, and longevity. As predicted, we find that a suite of important changes as a result of our selection on dispersal: high dispersal propensity is associated with a lower number of longer mating attempts by males, lower investment in early life reproduction by females, slower development of later-laid offspring, and longer female life span. These findings indicate that correlated intraspecific variation in dispersal and related traits may represent alternative life history strategies in T. castaneum. We therefore suggest that pest management efforts to mitigate the species' agro-economic impact should consider the eco-evolutionary dynamics within multiple life histories. The benefits of doing so could be felt both through improved targeting of efforts to reduce spread and also in forecasting how the selection pressures applied through pest management are likely to affect pest evolution. Graphical Abstract [ABSTRACT FROM AUTHOR]

CRISPR/Cas9 manipulations are possible in many insects and ever expanding. Nonetheless, success in one species and techniques developed for it are not necessarily applicable to other species. As such, the development and expansion of CRISPR-based (clustered regularly interspaced short palindromic repeats) genome-editing tools and methodologies are dependent upon direct experimentation. One useful technique is Cas9-dependent homologous recombination, which is a critical tool for studying gene function but also for developing pest related applications like gene drive. Here, we report our attempts to induce Cas9 homology directed repair (HDR) and subsequent gene drive in Tribolium castaneum (Herbst; Insecta: Coleoptera: Tenebrionidae). Utilizing constructs containing 1 or 2 target gRNAs in combination with Cas9 under 2 different promoters and corresponding homology arms, we found a high incidence of CRISPR/Cas9 induced mutations but no evidence of homologous recombination. Even though the generated constructs provide new resources for CRISPR/Cas9 modification of the Tribolium genome, our results suggest that additional modifications and increased sample sizes will be necessary to increase the potential and detection for HDR of the Tribolium genome. [ABSTRACT FROM AUTHOR]

Since the red flour beetle, Tribolium castaneum, feeds on starch, α-amylase is an important enzyme for hydrolyzing carbohydrates into sugar to meet energy demands. It has been reported that 20-hydroxyecdysone (20E) involve in the regulation of α-amylase in the red flour beetle. Injection of 20E decreased α-amylase activity in dose- and time-dependent manner. α-Amylase activity in males and females showed different patterns responding to 20E. Adults injected with high concentrations of 20E (300–500 ng/insect) had low levels of food consumption leading to a decrease in body mass. Interestingly, glucose levels in treated adults increased significantly in parallel with the increase in trehalase activity in both males and females. 20E down-regulated Amylase (TcAmy), while Trehalase-1 and -2 (TcTre-1 and -2, respectively) genes were up-regulated. Taken together, 20E caused a decrease in α-amylase activity directly at the level of gene expression and indirectly by repressing food consumption and causing low ingestion levels. However, understanding the mechanism(s) by which feeding behavior suppression is caused by 20E in the red flour beetle needs to be examined in the future. [ABSTRACT FROM AUTHOR]

Simple Summary: Due to issues with pesticide residues and resistance caused by traditional pesticides, the use of modified atmosphere storage technology has become increasingly popular. However, research has shown that prolonged exposure to high concentrations of CO2 for pest control in this technology can lead to insect resistance to hypoxia. Therefore, it is necessary to find out the resistance mechanism. This study identifies TcCYP6K1 and TcCYP9F2 as key factors in the response to high CO2 in Tribolium castaneum, suggesting that these genes may affect the resistance to high CO2 by influencing in the synthesis or breakdown of the carbohydrate metabolism pathways. These findings provide a theoretical basis for the combined use of novel nucleic acid pesticides and modified atmosphere treatment. Cytochrome P450 monooxygenases (CYP), crucial detoxification enzymes in insects, are involved in the metabolism of endogenous substances as well as the activation and degradation of exogenous compounds. In this study, T. castaneum was utilized to investigate the roles of TcCYP6K1 and TcCYP9F2 genes influencing in the trehalose metabolism pathway under high-CO2 stress. By predicting the functional sequences of TcCYP6K1 and TcCYP9F2 genes and analyzing their spatiotemporal expression patterns, it was discovered that both genes belong to the CYP3 group and exhibit high expression levels during the larval stage, decreasing during the pupal stage, while showing high expression in the fatty body, intestine, and malpighian tubules. Furthermore, following the knockdown of TcCYP6K1 and TcCYP9F2 genes in combination with treating larvae with 75% CO2, it was observed that larval mortality increased, and glycogen content significantly decreased, while trehalose content increased significantly. Additionally, membrane-bound trehalase enzyme activity declined, TPS gene expression was significantly upregulated, GS gene expression was significantly downregulated, and ATP content showed a marked decrease. In conclusion, CYP genes are critical responsive genes of T. castaneum to high CO2 levels, potentially impacting the insect's resistance to carbon dioxide through their involvement in the synthesis or breakdown of the carbohydrate metabolism pathway. These findings could serve as a theoretical basis for the utilization of novel pesticides in low-oxygen grain storage techniques and offer new insights for environmentally friendly pest control strategies in grain storage. [ABSTRACT FROM AUTHOR]

This study explores the use of essential oils from cardamom (Elettaria cardamomum (L.) Maton) and galangal (Alpinia galanga (L.) Willd) as alternatives to synthetic insecticides for controlling the red flour beetle, Tribolium castaneum (Herbst). The chemical compositions of these oils were analyzed using GC-MS, and their fumigation effects were tested in a vapor-phase bioassay. The experiment followed a factorial design with four types of essential oils, namely, those manually extracted from cardamom leaves (MCL) and galangal leaves (MGL) and those commercially produced from cardamom seeds (CCS) and galangal rhizomes (CGR), at seven concentrations (0, 50, 100, 150, 200, 250, and 300 µL/L air). The manually extracted oils yielded 0.6% from cardamom leaves and 0.25% from galangal leaves. MCL contained 28 components, with eucalyptol (25.2%) being the most abundant, while CCS had 34 components, primarily α-terpinyl acetate (46.1%) and eucalyptol (31.2%). MGL included 25 components, mainly caryophyllene (28.7%) and aciphyllene (18.3%), whereas CGR comprised 27 components, with methyl cis-cinnamate (47.3%) and safrole (19.8%) as the major constituents. The fumigation bioassay results revealed that CGR was the most effective, demonstrating the highest mortality rates of T. castaneum across all the tested periods and concentrations, achieving up to 96% mortality at 168 h with a concentration of 300 µL/L air. Statistical analyses showed significant differences in mortality based on the type and concentration of essential oil, particularly after 96 h. These findings highlight the potential of CGR, with its advantages and differences in chemical composition, as an effective biopesticide against T. castaneum, with increasing efficacy over time and at higher concentrations. [ABSTRACT FROM AUTHOR]

The research was conducted with meticulous attention to detail. The study aimed to discern the food precedence and investigate the various life stages of Tribolium castaneum. The research was carried out in two flour media, wheat (Triticum indicum) and rice (Oryza sativa), at an average temperature of 30°C and 50% R.H. The study found that larval and pupal development time was comparatively faster in wheat flour (23 to 27 days) as compared to rice (33 to 37). Oviposition was observed higher in rice flour than in wheat flour. Instars were discerned as six and seven in wheat and rice flour, respectively. The pace of reproduction, development, and growth was higher in the warmer seasons from April till the start of September, especially in June and July, but with the cessation of all these activities in fall and cold seasons, even adult beetles were found dead in extreme cold. [ABSTRACT FROM AUTHOR]

BACKGROUND: Wheat grain containers or silos can be perfect habitats for insects, which generate large economic losses to grain production. Natural alternatives to synthetic insecticides have grown in popularity because of health, economic and ecological issues. Diatomaceous earth is a natural compound that has an insecticide effect by enhancing an insect's dehydration with no toxicity on mammals including humans. The aim of this study is to confirm the effect of diatomaceous earth as an insecticide for the wheat grain pest, the red flour beetle Tribolium castaneum (Coleoptera: Tenebrionidae) and demonstrate its underlying mechanisms as an insecticide by open‐flow respirometry and scanning electron microscopy. RESULTS: Survival bioassays of T. castaneum revealed a dose‐dependent insecticide effect of diatomaceous earth. Gravimetric measurements showed that 2 days exposure to diatomaceous earth produces a significant increase of mass loss. Open‐flow respirometry measurements showed an increase of total water emission rate on insects due to an increase of both, respiratory and cuticular water loss. Our study revealed that diatomaceous earth produces an increase of insect's cuticle permeability, which is responsible for elevated cuticular water loss. Scanning electron microscopy images provided visual evidence of the lipid absorbent properties of diatomaceous earth particles, and showed a tendency for higher, although not significant, damaged area of the cuticle's surface from diatomaceous earth treated insects compared to control ones. CONCLUSION: With state‐of‐the art techniques like open‐flow respirometry and scanning electron microscopy, we demonstrated the underlying mechanism of diatomaceous earth as an insecticide and provided new cues for understanding the properties of the cuticle and its ecological importance. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Abstract Tribolium castaneum and Rhyzopertha dominica are cosmopolitan, destructive postharvest pests. Although research has investigated how high densities of T. castaneum affect attraction to the aggregation pheromone by conspecifics, research into the behavioral response of both species to food cues after high density exposure has been lacking despite its importance to foraging ecology. Our goal was to manipulate and observe the effects of crowding on the behavioral response of both species to common food and pheromonal stimuli and to determine how the headspace emission patterns from grain differed under increasing densities. Densities of colonies for both species was altered (10–500 adults) on a fixed quantity of food (10 g of flour or whole wheat), then the behavioral response to common food and pheromonal cues was evaluated in a wind tunnel and release-recapture experiment, while volatiles were examined through gas chromatography coupled with mass spectrometry. Importantly, at least for T. castaneum, crowded conditions attenuate attraction to food-based stimuli, but not pheromonal stimuli. Crowding seemed to have no effect on R. dominica attraction to food and pheromonal stimuli in the wind tunnel, but exposure to high density cues did elicit 2.1–3.8-fold higher captures in traps. The relative composition and abundance of headspace volatiles emitted varied significantly with different densities of beetles and was also species-specific. Overall, our results have implications for expanding our understanding of the foraging ecology of two economically important pests.

Movement plays a crucial role in animal behavior. However, despite the prevalence of uneven terrains in nature, many movement studies are conducted in arenas with smooth substrates. This discrepancy raises questions about the ecological validity of such experiments. To address this gap, we investigated the effect of rough substrates on movement properties using the red flour beetle (Tribolium castaneum) as a model organism. Our findings revealed significant variations in movement behavior between rough and smooth substrates. Notably, beetles traveled longer distances on smooth surfaces compared to sandpaper and loose sand. Moreover, variations in step size were influenced by substrate treatment, with the highest values observed on sand and sandpaper treatments. The proportion of time spent standing still also showed sensitivity to substrate conditions. The interaction between substrate properties and beetle sex further influenced several movement properties. Even the spatial configuration of rough and smooth areas in the arena had an impact on beetle movement, with areas along the arena perimeter exhibiting a stronger effect. These results highlight the impact of uneven terrain on beetle movement, underscoring the importance of considering environmental conditions when designing experimental setups. Here, this refers to the substrate on which animals move, but it may refer to other conditions, such as the test arena size and shape, temperature, humidity, and illumination. Failure to account for these background environmental conditions may result in inadvertently examining the interaction of the tested animals with these conditions, rather than focusing on the effect of the treatments applied in the experiment. [ABSTRACT FROM AUTHOR]

Animals from all major clades have evolved a segmented trunk, reflected in the human spine or the insect segments. These units emerge during embryogenesis from a posterior segment addition zone (SAZ), where repetitive gene activity is regulated by a mechanism described by the clock and wavefront/speed gradient model. In the red flour beetle Tribolium castaneum, RNA interference (RNAi) has been used to continuously knock down the function of primary pair-rule genes (pPRGs), caudal or Wnt pathway components, which has led to the complete breakdown of segmentation. However, it has remained untested, if this breakdown was reversible by bringing the missing gene function back to the system. To fill this gap, we established a transgenic system in T. castaneum, which allows blocking an ongoing RNAi effect with temporal control by expressing a viral inhibitor of RNAi via heat shock. We show that the T. castaneum segmentation machinery was able to reestablish after RNAi targeting the pPRGs Tc- eve, Tc- odd, and Tc- runt was blocked. However, we observed no rescue after blocking RNAi targeting Wnt pathway components. We conclude that the insect segmentation system contains both robust feedback loops that can reestablish and labile feedback loops that break down irreversibly. This combination may reconcile conflicting needs of the system: Labile systems controlling initiation and maintenance of the SAZ ensure that only one SAZ is formed. Robust feedback loops confer developmental robustness toward external disturbances. [ABSTRACT FROM AUTHOR]

The thrust of the study was to determine the chemical composition of the essential oils extracted from Thymus pallescens de Noé and Cymbogon citratus Stapf. as well as to evaluate their efficacy in controlling Sitophilus zeamais Motschulsky and Tribolium castaneum (Herbst) in either single or combined populations. Carvacrol (56.04%) and geraniol (20.86%) were identified as the major constituents of T. pallescens and C. citratus respectively. The tested essential oils showed pronounced insecticidal activity against the pest species in relation with the applied doses. T. pallescens EO had the highest efficacy and S. zeamais was found to be more susceptible to both individual and combined treatments. With reference to the contact and fumigation assessments, T. pallescens EO effectuated corrected mortality rates ranging from 42.5–100% to 25–100% in S. zeamais with corresponding lethal concentration (LC50) values of 17.7 µl/ml and 15µL/L air respectively. Whereas, the T. pallescens EO exhibited corrected mortality rates of 42.5–100% and 20–100% with corresponding LC50 values of 18.1 µl/ml and 15.5 µL/L air against T. castaneum in contact and fumigation assessments, respectively. The corrected mortality rates increased for both insect species when using combination treatments, with significant increases in the LC50 values, ranging from 8.59 to 49.9% for both pest species. Analysis of energy biomarkers in the treated insects indicate significantly increased protein and carbohydrate contents and decreased lipids levels. The study therefore demonstrated the bio-insecticidal toxicity of the EOs from T. pallescens and C. citratus against two important maize post-harvest pests, concurrently revealing significant positive and negative insecticidal activity gradients in relation to single or combined populations. [ABSTRACT FROM AUTHOR]

Many species often show male–male combat for mating opportunities and resources within the species. Sexual selection through this radical combat leads to the evolution of males with exaggerated traits used as weapons, such as horns or mandibles, that often result in victory during combat. However, heterospecific interaction due to errors in species identification has often been observed, which results in decreased mating opportunities within the same species and fewer fertilized eggs. Males with exaggerated weapons may show dominance in resource acquisition over males without weapons and may decrease the reproductive success of the latter due to competition between the two. However, few studies have examined heterospecific interaction focusing on males with or without weapons. In this study, we investigated the effects of the male weapon on reproductive traits in heterospecific interaction in two species: the broad‐horned flour beetle (Gnatocerus cornutus), in which males have exaggerated weapon traits; and the red flour beetle (Tribolium castaneum), in which males have no weapon traits. Both species are closely related and use the same food resources. G. cornutus males interfered with the resource acquisition and reproductive opportunities of T. castaneum by attacking T. castaneum. The reproductive success of T. castaneum decreased when they cohabited with G. cornutus males. These findings show that male weapon traits, which are important for sexual selection within the same species, can also greatly influence reproduction in other species. [ABSTRACT FROM AUTHOR]

The present study investigated the insecticidal efficacy of Diaterra®, a native diatomaceous earth, against two significant stored grain pests, the grain weevil, Sitophilus granarius (Linnaeus, 1758), (Coleoptera: Dryophthoridae) and the red flour beetle, Tribolium castaneum (Herbst, 1797) (Coleoptera: Tenebrionidae). To control of insect pests in stores or warehouses, grain industry relies on synthetic insecticides, but they have significant environmental and health risks. Diatomaceous earth offers a natural and environmentally friendly alternative. In addition, it is safe for wildlife, leaves no residues, and effectively controls pests. In the study, different doses (0.25, 0.5, 1, 2, and 4 g/m2) of diatomaceous earth were applied on concrete and wooden surface. A mortality of 100.0% was achieved for S. granarius on the wooden surface at a dose of 4 g/m2 during the 96-hour and subsequent application periods, whereas for T. castaneum, this rate was recorded as 88.9% under the same dose and a 192-hour application period. On the concrete surface, a mortality rate of 100.0% was achieved for S. granarius at a dose of 4 g/m2 after 120 h of exposure. In contrast, for T. castaneum, this rate did not exceed 59.5% even with the same dose and a 192-hour application period. Under controlled laboratory conditions, a dose of 4 g/m2 of Diaterra® showed efficacy in managing S. granarius populations on wooden and concrete surfaces. The desired level of efficacy was not achieved for T. castaneum on either surface type. Based on the data obtained from this study, it can be concluded that prolonged exposure to diatomaceous earth leads to enhanced insecticidal efficacy against both S. granarius and T. castaneum on different surface types. This study emphasizes the importance of considering application duration and surface type as critical factors in maximizing the effectiveness of diatomaceous earth applications. [ABSTRACT FROM AUTHOR]

The present research describes the utilization of plant aqueous extracts for more sustainable and safe management red flour beetle (Tribolium castaneum Herbst); a highly concerned pest of stored rice and wheat grains in tropical and subtropical regions. The aqueous extracts of selected parts of Nigella sative, Coriandrum sativum, Ocimum basilicum, Neriwn oleander, Tamarindus indica, Chrysanthemum indicum, Linum usitatissimum, Myristica fragrans, Citrullus colocythis, and Musa acuminate plants were prepared by simple orbital type shaking and tested for their repellent and insecticidal activities. Besides, the phytochemical constituents and phenolic acids were identified by various spectroscopic assays and RP-HPLC-DAD analysis, respectively. The initial screening revealed that the aqueous extracts of Myristica fragrans nutmeg, Citrullus colocythis leave, Coriandrum sativum leaves Ocimum basilicum can exhibit the insect repellent potential of about 86.66% when applied at or above 1000 µg/ml for 24 h. It was interesting to note that the similar concentration of aqueous extracts of Myristica fragrans nutmeg, Citrullus colocythis (leaves), and Coriandrum sativum (leaves) caused 100% percent mortality of red flour beetle at the end of seven days under ideal growth conditions (28 ± 2° C and 70 ± 5% RH). Overall, the aqueous extracts of Myristica fragrans nutmeg and Citrullus colocythis leaves were found to be more potential candidates for the sustainable management of Tribolium castaneum during post-harvest storage of wheat and rice grains. [ABSTRACT FROM AUTHOR]

The essential oil (EO) extraction is one of the ways to utilize of grapefruit (Citrus paradisi L.) peel waste. However, the low stability and penetration problems of EO limit their use. These limitations can be overcome by nanoemulsions. Therefore, this study aimed to form and characterize of the grapefruit peel essential oil nanoemulsion (EO N) and investigate its insecticidal properties against Sitophilus granarius (Linnaeus, 1875) and Tribolium castaneum (Herbst, 1797) for an alternative bio-economic way. The grapefruit peel EO N (4:3:3:90 w/w, EO:Tween 80:Ethanol:water) was formed by using the grapefruit peel EO with major chemical components such as d-limonene (85.70 %), myrcene (3.57 %), α-pinene (1.17 %). The grapefruit peel EO N was characterized by TEM (50–120 nm), Zeta sizer (the mean droplet particle size: 109.3 nm, ζ-potential value:-20.6 mV, polydispersity index:0.265) and FT-IR analysis. 500 ppm of the grapefruit peel EO N caused 50 % and 20 % mortality in S. granarius and T. castaneum after 7 days, respectively. 1000 ppm of the grapefruit peel EO N caused 85 % and 50 % mortality in S. granarius and T. castaneum after 7 days, respectively. Based on the findings, the grapefruit peel EO N may be considered having the potential to integrate management strategies for these pests and open a new bio-economic way. [Display omitted] • One of the ways to evaluate grapefruit peel waste is essential oil (EO) extraction. • Limitations on the use of EO can be overcome with nanoemulsion (N) form. • Grapefruit peel EO N (50–120 nm and −20.6 mV of ζ potential) was formed. • Grapefruit peel EO N showed a higher toxicity against S. granarius than T. castaneum. • EO N can be one of bio-economic ways of grapefruit peel waste in pest management. [ABSTRACT FROM AUTHOR]

Phosphine is the most common fumigant used for stored product protection, and its use intensified with the global phasing out of methyl bromide due to its ozone depletion characteristics. These use patterns led to phosphine resistance, which was subjected to a globe-wide survey in the 1970's, but without a subsequent (global) update. Thus, the present work aimed to undertake a comprehensive review of the phosphine resistance literature published since the initial survey in 1975 until 2021. Next, meta-analyses were used to synthesize and quantify the resistance observed within the main insect pest species of stored products. Forty-six papers were recognized surveying 13 species of stored product insect species, encompassing 980 populations around the world; 72.96% of these populations exhibited phosphine resistance, and 10 out of the 13 species evaluated exhibited resistance in more than 60% of the populations tested. The most widespread problems were observed with the lesser grain borer (Rhyzopertha dominica), the rice weevil (Sitophilus oryzae), and the red flour beetle (Tribolium castaneum). The frequency of resistant individuals ranged from 12 to 48% for the populations. The levels of phosphine resistance were higher for the lesser grain borer (73-fold on average), followed by the red flour beetle (32-fold), and the maize weevil (28-fold). Furthermore, a considerable variability was observed within species and among localities. Therefore, phosphine resistance remains an ongoing problem and worldwide concern, with increasing levels and prevalence among key pest species of stored products, although reports and monitoring are largely circumscribed to four countries–Australia, Brazil, Greece, and the US. [ABSTRACT FROM AUTHOR]

The red flour beetle, Tribolium castaneum, is the most common coleopteran pest that infests different kinds of stored grains and flours. Under natural conditions, T. castaneum adults secrete benzoquinones as cuticular semiochemicals for aggregation and defensive purposes. In this study, we have examined the physico-chemical effects on the secretion of cuticular semiochemicals in T. castaneum. Adult beetles were exposed to different food flours, starvation, cold, heat and chemical treatments. After 24 h of exposures, cuticular surface chemicals were extracted and analyzed using gas chromatography–mass spectrometry (GC–MS) and gas chromatography–flame ionization detector (GC–FID) techniques. Totally, 14 compounds were identified as cuticular surface chemicals from the body surface of beetles. When exposed to different food flours (chickpea, green gram, rice and wheat), there were no remarkable variations in the secretion of cuticular surface chemicals. Whereas under starvation, cold, heat and chemical stress conditions, remarkable variations (significantly at P ≤ 0.05) were observed in 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions. Remarkably, maximum 99.30, 98.79 and 77.41% reductions were observed in 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions due to the effect of diallyl disulfide chemical stress, respectively, with the significance of P ≤ 0.05. In conclusion, it was predicted that starvation, cold, heat and chemical stress conditions alter 2-methyl-p-benzoquinone, 2-ethyl-p-benzoquinone and 1-pentadecene secretions in T. castaneum adults rather than food flours. [ABSTRACT FROM AUTHOR]