Tribolium Castaneum Research Articles

Bioassays of Fumigant Toxicity and Repulsiveness of Haplophyllum tuberculatum Extracts

Abstract 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.

The quest for the best target genes for RNAi-mediated pest control.

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.

Chemical composition and repellent effects of powders and essential oils from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

The present study evaluated the chemical composition and the potential repellent effect of powders and essential oils (EOs) from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against T. castaneum adults. The EOs were extracted by the hydrodistillation method, and their chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS) analysis. The repellent effect of powders and EOs was assessed using the area preference method. GC-MS revealed that the major components of the studied EOs were α-pinene (28.27%) and cubenol (10.75%) for J. phoenicea, β-Eudesmol (23.74%), hedycaryol (12.54%), and olopanone (10.04%) for J. oxycedrus, and oplopanone (26.84%) and α-Santanol acetate (17.28%) for J. thurifera. The powders of three Juniperus species had a repellent effect (class IV) against T. castaneum adults. Among the powders tested, J. phoenicea had the highest average repellency rate of 75.40%, followed by J. oxycedrus with 62.30%, and J. thurifera had the lowest average repellency rate of 60.30%. Moreover, J. phoenicea EO had the highest average repellency rate of 72.50%, followed by J. oxycedrus with 67.40%, while J. thurifera had the lowest average repellency rate of 61.80%.The potential of Juniperus species can be used as biopesticides to control T. castaneum infestations as an alternative to synthetic pesticides.

Long-read genome assembly of the insect model organism Tribolium castaneum reveals spread of satellite DNA in gene-rich regions by recurrent burst events.

Eukaryotic genomes are replete with satellite DNAs (satDNAs), large stretches of tandemly repeated sequences that are mostly underrepresented in genome assemblies. Here we combined nanopore long-read sequencing with a reference-guided assembly approach to generate an improved, high-quality genome assembly, TcasONT, of the model beetle Tribolium castaneum Enriched by 45 Mb in repetitive regions, the new assembly comprises almost the entire genome sequence. We use the enhanced assembly to conduct global and in-depth analyses of abundant euchromatic satDNAs. Unexpectedly, we show the extensive spread of satDNAs in gene-rich regions, including long arrays. The sequence similarity relationships between satDNA monomers and arrays indicate a recent exchange of satDNA arrays between different chromosomes. We propose a scenario of their genome dynamics characterized by repeated bursts of satDNAs spreading through euchromatin, followed by a process of elongation and homogenization of arrays. We find that suppressed recombination on the X Chromosome has no significant effect on the spread of satDNAs but the X rather tolerates the amplification of satDNAs into longer arrays. Analyses of arrays' neighboring regions show a tendency of one satDNA to be associated with transposable-like elements. Using 2D electrophoresis followed by Southern blotting, we prove Cast satDNAs' presence in the fraction of extrachromosomal circular DNA (eccDNA). We point to two mechanisms that enable this satDNA spread to occur: transposition by transposable elements and insertion mediated by eccDNA. The presence of such a large proportion of satDNA in gene-rich regions inevitably gives rise to speculation about their possible influence on gene expression.

The cryptonephridial/rectal complex: an evolutionary adaptation for water and ion conservation.

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.

Isolation, Identification and Evaluation of the Effective Phyto-Compounds for The Management of Groundnut Beetles Infesting Stored Groundnut (Arachis Hypogaea L.)

The effectiveness of various botanicals was tested against the Major Pest of shelled groundnuts, the red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenbebrionidae), under artificial infestation, in Laboratory conditions for one year. Essential Oils isolated by Clevengers Apparatus , @1%v/w of Pongamia glabra (Karanja Oil), Azadirachta indica (Neem Oil), Brassica campestris (Mustard Oil) , Crown oil (Resin of Shorea robusta) , Dalbergia sisso (Sisso Oil), Oryza sativa (Rice bran oil), Helianthus annus (Sunflower Oil) , Ricinus communis (Castor Oil), Aegle marmelos (Bael Oil), Sesamum indicum (Til Oil), etc were tested for their bioefficacy against the Major Pest, of shelled groundnuts, red flour beetle Tribolium castaneum, (Herbst) Tenebrionidae, Coleoptera, under artificial infestation, in Laboratory conditions for one year. Out of all these plant products only, Crown oil (Resin of Shorea robusta) gave 100 % pod/Kernel protection for one year. The LD 50 values were found out to be - 0.5% v/w. Spectroscopic GC MS analysis of, Crown oil (Resin of Shorea robusta) are identified as 2-Ethyl-oxetane (RT 2.223), as the major product It may be due to the strong aromatic nature of these phyto-product. Hence these phyto-product may be used as fumigants or insect repellants against Tribolium castaneum and can be included in the package of practices to save stored groundnut in storage.

In vitro cytotoxic evaluation of Hypericum perforatum and molecular docking and dynamic analysis of PINK-1 inhibitors on model organism Tribolium castaneum and Homo sapiens

Hypericum species are especially known for their pharmacological characteristic. One of the major component of the plant is hypericin that can be used in tumor inhibition with its potent cytotoxic effects. In this study, the anticancer effect of H. perforatum essential oil on the MCF-7 breast cancer cell line was examined, and the binding potential of the compounds of Hypericum perforatum L., hypericin, hyperoside and hyperforin, to the PINK1 protein of both human and model organism, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) was investigated in silico. Recently, many insect species have been proposed as model organisms, including T. castaneum, that the first species with whole genome sequenced. Worlwide distribution of insects, their environmental importance and realtively inexpensive cultivation have increased the interest in them Therefore, in in silico studies, T. castaneum was used as a model to compare binding similarities with humans and model organisms. In the study, the IC50 concentration of H. perforatum L. on MCF-7 cells was determined to be 98.765 μg/ml. Based on in silico findings, the most favorable binding affinity of -12.5 kcal/mol was observed between the Hypericin molecule and the insect PINK1 protein. The fact that these plant components bind with high energy to the PINK1 protein, which is believed to guard cells from mitochondrial dysfunction triggered by stress, is promising for the development of plant-based medical drugs and biopesticides.

Insecticidal effect of two Turkish entomopathogenic nematode isolates against Tribolium castaneum (Herbst) larvae and adults at different conditions

Red flour beetle, Tribolium castaneum (Herbst.), is the most common pest of stored grains and products. Aerial and contact pesticides are used to control this pest. However, the red flour beetle has also developed significant resistance to phosphine, the main fumigant currently in use worldwide. The adverse effects of pesticides on non-target organisms, groundwater contamination, residues on food crops, and the emergence of insect resistance to chemicals have compelled the industry to prioritize the development of alternative control measures. Entomopathogenic nematodes find application in various agricultural systems. The insecticidal effect of two isolates of Steinernema feltiae Filipjev (Nematoda: Steinernematidae) and Heterorhabditis bacteriophora Poinar (Nematoda: Heterorhabditidae) against the different stages of T. castaneum. The entomopathogenic nematode isolates were examined at four concentrations (0, 250, 500, and 1000 IJs/ml) with a distilled water at 15 and 25 ± 1 °C temperatures. Results revealed that both S. feltiae (A-16) caused with 92.33% mortality rate while H. bacteriophora (O-7) caused with 76.77% mortality in the last instar larvae of the red flour beetle while these two species caused 75.38% and 66.85% mortality in adults, at 25 °C. The effect of nematodes decreased as the temperature decreased. According to results, the mortality rate of T. castaneum larvae treated with S. feltiae (A-16) with (54.62%) was significantly higher than that of H. bacteriophora (O-7) with (32.13%) 96 h after inoculation at 15 °C. The data indicated that 1000 IJs/ml was the most effective concentration of tested EPN isolates for all larval and adult stages.In this study, our findings indicate that S. feltiae (A-16) and H. bacteriophora (O-7) can be used as effective biological control agents against both the larval and adult stages of the red flour beetle. The results demonstrate that EPNs are promising candidates for biocontrol of T. castaneum. This information is useful in designing future biological control programs.

Insect pests of dried yam (Dioscorea sp.) chips and the perception of processors and marketers on their control

This survey was aimed at understanding the perception of Dried yam chips (DYC) Processors and Marketers on insect pests' infestation of DYC and their damage through the use of structured questionnaires. Data on socio-economic characteristics and technical information were analyzed using descriptive statistics such as frequency distribution, percentages, and means. Data on the perception of insect pests and measures of pest control were placed on a 3-point Likert Rating Scale (LRS). Analysis of variance (ANOVA) was done on the population density of the identified insects and significant mean values were compared using Fisher's Least Significant Difference. Seven insect pests; Prostephanus truncatus, Rhyzopertha dominica, Tribolium castaneum, Stegobium paniceum, Heterobostrychus aequalis, Sitophilus zeamais, Areacerus fasciculatus, and one natural enemy; Peregrinator biannulipes were associated with DYC. However, P. truncatus, R. dominica, and A. fasciculatus were the most prevalent insect pests, causing significant damage to DYC. Approximately, 49% of processors reportedly control insect infestation in DYC using conventional insecticides, 23% by re-drying, 14% by botanicals, and the others by removing affected DYC. These findings provide useful information for extension workers involved in community education, and intervention programs by government or non-governmental organizations including public health experts and researchers.

Insecticidal and Microbial Effect of Essential Oil on Wheat and Chickpea During Storage

In recent years, limited research works has been reported on the use of integrated pest management to control the insect and pests in stored grain. Management of stored grain insects and pests using essential oils either in combination or alone will be of great importance as it is economical and eco-friendly. Tests were conducted to evaluate the toxicological impact of essential oils on stored product beetles in wheat and chickpea storage, as well as their influence on germination characteristics. The impact of essential oils was assessed for their fumigant toxicity, mortality, repellent properties, and effects on germination against storage pests such as Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum, and Collasobruchus chinensis in wheat and chickpea. During the fumigant toxicity test the selected essential oils either alone at 0.4 percent or in combination at 0.2 percent each were highly effective against Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum, Collasobruchus chinensis. All the essential oils at 0.4% concentration demonstrated complete mortality within twenty-four hours of treatment against Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum, and Collasobruchus chinensis, compared to untreated samples. The evaluated essential oils exhibit the greatest repellent activity against Sitophilus oryzae, Rhyzopertha dominica, Tribolium castaneum, Collasobruchus chinensis. Whether applied individually at a concentration of 0.4% or in combinations at 0.2%, they show no impact on the percentage of germination, vigour index, and viability significance after eight and ten months of storing wheat, respectively.

Novel regulation pathway of eclosion hormones in Tribolium castaneum by distinct transcription factors through the initiation of 20-Hydroxyecdysone

Eclosion hormone (EH) is not only a key trigger of insect ecdysis, but is also involved in the regulation of important physiological processes such as development, diapause, metamorphosis and reproduction. EH is an ideal target for RNAi treatment and prevention of the Tribolium castaneum. However, two EH genes in Tribolium castaneum demonstrate distinct replication and functional conversion relationships, and the mechanisms of transcriptional regulation of eclosion hormone remain largely unexplored and poorly understood. In this study, the activity of highly active promoter fragments and potential transcription factors of TcEH and TcEHL were identified using the Dual-Luciferase reporter system and TANSFAC. TcSlbo and TcCAD were revealed to be important transcription factors for TcEH and TcEHL, respectively. Knockdown of TcSlbo failed to slough off the old epidermis of Tribolium castaneum and prevented them from developing into adults. Furthermore, we demonstrated for the first time that 20-hydroxyecdysone (20E) affects the expression of TcEH and TcEHL by regulating the transcriptional activities of TcSlbo and TcCAD. This study provides new insights into the transcription regulation of TcEH and TcEHL, their roles in insect growth and development, and the involvement of 20E in eclosion regulation, offering potential molecular targets for future pest management strategies.

Metabolic Adaptations in Phosphine-Resistant Tribolium castaneum Driven by Mitochondrial Enzyme Variability and Gene Expression.

Phosphine fumigation is essential for controlling storage pests like Tribolium castaneum, but its frequent application has resulted in resistance, primarily due to mutations in the Dihydrolipoamide dehydrogenase (DLD) gene associated with the rph2 allele. This study demonstrates that the Patiala population exhibits homozygous resistance variations across populations, contrasting with the susceptibility observed in laboratory cultures. Our assessment of mitochondrial DLD and Cytochrome c oxidase (COX) activities showed significantly elevated levels in the Patiala population, with increases of approximately sevenfold for DLD and 6.92-fold for COX, indicating mitochondrial adaptations for enhanced energy production. Kinetic analyses of DLD in the resistant Patiala population showed a higher Vmax (0.005 mmol/min) and a significantly increased Km (16.66 mM), indicating variations in maximal enzyme activity and substrate affinity. Furthermore, resistant T. castaneum populations displayed substantial upregulation of DLD and COX gene expression, with DLD expression increasing by 10.53-fold and COX expression peaking at 102.57-fold in Patiala. Pearson correlation analysis indicated strong positive correlations (r > 0.8) between enzymatic activity and gene expression for both DLD and COX, suggesting a coordinated role in resistance mechanisms. The PCA biplot illustrated distribution patterns of enzymatic activity and gene expression among field-resistant populations, highlighting the association between increased resistance and elevated enzymatic activity and gene expression levels. Therefore, the upregulation of DLD and COX activities in resistant populations underscores their critical roles in counteracting phosphine, reflecting metabolic reprogramming for improved energy production under stress.

Insecticidal and Repellent Activity of Essential Oils from Seven Different Plant Species against Tribolium castaneum (Coleoptera: Tenebrionidae).

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.

Chemical analysis of Viloa odorata L. (Fam. Violaceae) and the efficacy of its essential oil against some stored product insects

The current experiment was carried out to assess the insecticidal activity of sweet violet (Viola odorata) essential oil against three major stored product insects (Tribolium castaneum, Rhyzopertha dominica and Sitophilus oryzae). The chemical composition of sweet violet essential oil in different cuts (first, second and third cut) of V. odorata grown in Al-Gharbia governorate, Egypt was determined. For the first cut, 73.825 % linolenic acid was the main component, while for second cut, 61.000 % linolenic acid was the main component and for the third cut, the main component was 75.419 % linolenic acid. The biomass yield was changed on different cuts. In the first cut, the yield was 15.500 ton/acre while it was 10.300 and 6.800 ton/acre for the second and the third cut respectively. In mixing with medium experiment, Triboleum castaneum was the most tolerant insect against violet absolute essential oil while after one day of exposure Rhizobirtha dominica was the most sensitive insect with LC50 of 53730 mg/kg. After 24 h of exposure in thin film experiment, R. dominica was found to be the most sensitive insect with LC50 of 475 mg/L. At the highest concentration (15000 mg/kg) there were no emerged adults for T. castaneum and S. oryzae while there were a mean of 0.33 emerged adults for R. dominica. The reduction was 100 % at the highest concentration for S. oryzae and T. castaneum while it was 99.53 % for R. dominica.

Assessment of Piper longum L. (Piperaceae) leaves toxicity on the adults of Tribolium castaneum (Herbst, 1797) (Coleoptera: Tenebrionidae)

BackgroundNumerous 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.ResultsSignificant 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.ConclusionsThe 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.

Density dependent survival drives variation in density dependent population growth of an insect pest

Several ecological processes – from population dynamics to species co‐existence – are driven by density dependence (DD) in population growth rate. Thus, to predict and manage ecological outcomes, we need a deep understanding of which factors and demographic traits drive variation in DD. In the insect pest Tribolium castaneum, we found large variation in DD across habitats but not across source populations. We modeled DD in population growth as the product of DD in fecundity and survival, experimentally estimating each parameter. Across habitats, survival parameters varied more than fecundity, including in simulations with varying parameter values. Thus, DD in survival drives variation in density‐dependent population growth. Hence, under strong density‐dependent selection, we expect evolutionary change in density‐dependent survival, provided sufficient genetic variance. Our general framework combining detailed experiments and simulations with a simple model can be used for other species to better understand the causes and consequences of density dependent population growth.

Efficient CRISPR‐mediated genome editing can be initiated by embryonic injection but not by ovarian delivery in the beetle Tribolium castaneum

Efficient CRISPR‐mediated genome editing can be initiated by embryonic injection but not by ovarian delivery in the beetle <i>Tribolium castaneum</i>

Knockdown of TcGluCl leads to the premature pupation of Tribolium castaneum larvae possibly by influencing the calcium-mediating hormone homeostasis

The glutamate-gated chloride channels (GluCls) are widely existed in the neural and nonneural tissues of invertebrate. In addition to play important roles in signal transduction, the GluCls also showed multiple physiological functions in insects such as participate in the juvenile hormone synthesis. In the present study, the potential roles of TcGluCl in growth and development of the red flour beetle Tribolium castaneum were explored. Knockdown of TcGluCl showed no effects on the survivability, weight growth, final pupation rate, eclosion and fecundity of T. castaneum, whereas resulted in the significant premature pupation of larvae. Inhibition of TcGluCl expression significantly changed the levels of juvenile hormone and ecdysone as well as the expressions of hormone biosynthetic genes. The increased ecdysone level and decreased juvenile hormone level were observed at the late stage of dsGluCl-treated larvae. Knockdown of TcGluCl significantly reduced the expressions of TcSTIM1 and TcOrai1, which were the primary proteins in store-operated calcium entry (SOCE) mediated Ca2+ influx mechanism. Whilst the L-glutamic acid treatment led to the increased TcOrai1 expression in T. castaneum. These findings suggested that knockdown of TcGluCl increased the ecdysone level and contributed to the premature pupation of larvae, which might be due to the reduced Ca2+ influx caused by the decreased expressions of TcSTIM1 and TcOrai1. These studies provide novel insights on the function of GluCls in insects.

Nutrition affects larval survival and the development of morphological traits in male and female flour beetles, but genital size and shape remains canalised.

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.

Experimental evolution reveals that males evolving within warmer thermal regimes improve reproductive performance under heatwave conditions in a model insect.

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 T. castaneum populations to divergent thermal regimes (30°C versus 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.