Castaneum Adults Research Articles

Seed-Specific Dynamics: Unraveling Progeny Emergence Patterns in <em>Tribolium castaneum</em> (Herbst) (Coleoptera: Tenebrionidae) Infestations

Edible seeded crops are important nutrient source for both human and animals. Among the various causes of grain losses before consumption, stored-product pests claim an important place. Tribolium castaneum (Herbst) damages a wide array of food commodities including grains, during storage, but the information on progeny emergence on certain commodities still remains unexplored. A laboratory experiment was conducted to evaluate the progeny development of T. castaneum in commonly used edible seeds during storage. Twenty, one-month-old T. castaneum adults were introduced to 30 g samples of each seed type, with four replicates tested. Except for dhal and groundnut, all the other edible seed types were used only as whole seeds. Test samples of dhal and groundnut were used in their whole form as well as 50% broken seeds. Samples were maintained at 30±1°C and 65±1% relative humidity. After 7 days, adults were removed, and samples were kept for progeny development. Progeny adults and larvae were counted at 30 and 60 days. The adult progeny emergence was highest in oats, sesame and proso millet (Meneri). Larval emergence was higher in dhal (50% broken), groundnut (50% broken), barley and proso millet (Meneri). These findings provide important insights into the infestation of edible seeds by T. castaneum and opens-up avenues for adopting suitable methods to protect these during storage. As the presence of broken seed enhances the progeny development of T. castaneum, preventing such occurrences during grain processing and maintaining cleanliness are important practices during postharvest operations.

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.

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.

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.

Studies on the Response of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) to Multicolour Light System

Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) commonly known as rust red flour beetle was a universal pest of stored produce with an extensive feeding diversity. The management of T. castaneum in field conditions was through fumigation and spraying of suitable insecticides. Even though many plant products were found effective against pests in invitro conditions, they could not be mixed with the stored produce for fear of losing the table quality. Physical forces seemed to be good alternatives to chemical treatment as far as stored grain pests were concerned. The use of gamma and UV radiations, microwaves and ultrasonic sound waves against T. castaneum and other stored grain pests had been tried by many authors. The objectives of this study were to check the adult beetles and final instar grubs of T. castaneum to different colours of light and it showedpreference for clear tungsten (white) light, while they were averse to red coloured light. This trend was explicit even after the entrainment of beetles to red colour light for further generations. Based on these results it could be presumed that T. castaneum adults preferred to move away from red coloured light. By changing the colour of bright light to dark lighting in warehouses, it could be possible to manage T. castaneum in small measure. Total eradication of stored product pests like T. castaneum was at least possibility and the selection of a proper management system could help to solve the stored produce pest problem to a greater magnitude.

Antifeedant and growth inhibitory effects of extracts from Ajania potaninii and A. fruticulosa against Tribolium castaneum (Coleoptera: Tenebrionidae)

This study aimed to evaluate the nutritional and antifeedant indices of Tribolium castaneum in response to the compounds and main chemical constituents ofAjania potaninii and A. fruticulosa. These mainly includes essential oils and their major ingredients (eucalyptol, camphor, myrtenol, verbenol, and borneol), as well as nonvolatile compounds. The A. fruticulosa and A. potaninii EOs exhibited clear antifeedant activity against T. castaneum adults at a 2 mg/L concentration, with FDI of 50% and 60%, respectively. Among the nonvolatile compounds, sesamin and eriodictyol exhibit strong antifeedant activities against T. castaneum adults at the same concentration, with an FDI of 90.57% and 88.68% after 72 h, respectively. For larvae, A. fruticulosa and A. potaninii EOs also resulted in antifeedant activity (respective FDI: 57.08% and 55.63%). In addition, sesamin and eriodictyol had exceptionally potent antifeedant activity against T. castaneum larvae, with FDI values 90.71% and 96.17%, respectively. In nutritional studies, the reductions in relative food consumption rate (RCR) of T. castaneum were more pronounced for 1 mg/L and 2 mg/L of either eucalyptol or sesamin. However, at greater concentrations, the conversion efficiency of eucalyptol and sesamin to ingested food in T. castaneum was significantly improved. Eucalyptol and sesamin showed a dose-dependent FDI for this insect. Considering the significant anti-insect activities, the EOs, main compounds, and non-volatile compounds of both A. potaninii and A. fruticulosa might be useful in devising integrated pest strategies, providing a promising perspective for the comprehensive use of natural plant resources from the Ajania genus.

Effects of nutrition on recovery, mortality, and mobility of adult Tribolium castaneum after exposure to long-lasting insecticide-incorporated netting.

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. 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. 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.

Influence of molecular descriptors of plant volatilomics on fumigant action against the three major stored product beetle pests.

Plant volatilomics such as essential oils (EOs) and volatile phytochemicals (PCs) are known as potential natural sources for the development of biofumigants as an alternative to conventional fumigant pesticides. This present work was aimed to evaluate the fumigant toxic effect of five selected EOs (cinnamon, garlic, lemon, orange, andpeppermint) and PCs (citronellol, limonene, linalool, piperitone, andterpineol) against the Callosobruchus maculatus, Sitophilus oryzae, and Tribolium castaneum adults. Furthermore, for the estimation of the relationship between molecular descriptors and fumigant toxicity of plant volatiles, quantitative structural activity relationship (QSAR) models were developed using principal component analysis and multiple linear regression. Amongst the tested EOs, garlic EO was found to be the most toxic fumigant. The PCs toxicity analysis revealed that terpineol, limonene, linalool, and piperitone as potential fumigants to C. maculatus (< 20 µL/L air of LC50), limonene and piperitone as potential fumigants to T. castaneum (14.35 and 154.11 µL/L air of LC50, respectively), and linalool and piperitone as potential fumigants to S. oryzae (192.27 and 69.10 µL/L air of LC50, respectively). QSAR analysis demonstrated the role of various molecular descriptors of EOs and PCs on the fumigant toxicity in insect pest species. In specific, dipole and Randic index influence the toxicity in C. maculatus, molecular weight and maximal projection area influence the toxicity in S. oryzae, and boiling point and Dreiding energy influence the toxicity in T. castaneum. The present findings may provide insight of a new strategy to select effective EOs and/or PCs against stored product insect pests.

Insect-resistant activities of Elsholtzia ciliata essential oil and its main components carvone against Tribolium castaneum in different development stages

The main objectives of the present study are to introduce a ecologically safe, and natural compound for controlling the red flour beetle, Tribolium castaneum. This study aims to thoroughly examine the effects of Elsholtzia ciliata essential oil (E. ciliata EO) and its primary components, carvone, on Tribolium castaneum eggs, larvae, pupae, and adults. The study also includes a simulated warehouse test to assess the efficacy of these substances as contact agents, fumigants, repellents, and antifeedants. All of these anti-insect activities were positively correlated with the concentrations of E. ciliata EO and carvone. Firstly, in the contact activity assay, E. ciliata EO and carvone completely inhibited the hatching of eggs and pupae of the T. castaneum at a concentration of 2.5 μL/cm2. The LC50 of E. ciliata EO and carvone were 7.62 and 4.33 μg/adult, respectively, against senior adults (5 weeks old). Secondly, in the fumigant activity assay, 60 mg/L of E. ciliata EO and carvone essentially completely inhibited pupae eclosion. On the other hand, the LD50 of E. ciliata EO and carvone against senior adults (5 weeks old) were 8.72 and 5.02 mg/L, respectively. Thirdly, for T. castaneum adults, at the highest test concentration, the repellent rate of the E. ciliata EO was above 90%. Fourthly, the larvae and adults of the T. castaneum could reach complete antifeedant activity by E. ciliata EO and carvone at the highest test concentrations. Finally, 3000 ppm of carvone was sufficient to kill all the pests in the warehouse in the simulated warehouse test. In conclusion, the results of this study will contribute to the better control of the storage pest, T. castaneum, and the development of environmentally friendly insecticides based on E. ciliata EO and carvone.

EFFECT OF PRE-EXPOSURE ON THE INSECTICIDAL AND REPELLENCY PROPERTIES OF Citrus paradisi PEEL ESSENTIAL OIL AGAINST Tribolium castaneum

Although the use of essential oils (EOs) for pest control has gained popularity due to their biodegradability and ecological safety, a major concern regarding their use is stability. Therefore, this aspect deserves empirical studies to enable potential end users to adopt research findings on the pesticidal potential of EOs. This research investigated the insecticidal and repellence impacts of Soxhlet-extracted grapefruit peel (Citrus paradisi Macfad. (Rutaceae) Lane) EO pre-exposed to air for 0, 0.5, 1 and 2 h (before introducing insects) on Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae). The ethanol diluents were initially allowed to evaporate for 15 min in all treatments. Contact toxicity was tested on larval and adult stages at 5 and 15% concentrations of the EO, while repellency was tested at a 5% concentration. The impacts of EO on adult behavioural activity were also observed 24 h after exposure. Grapefruit EO was effective in controlling T. castaneum adults and larvae at higher doses. Exposure periods had an immediate significant effect on larvae and adult mortalities 1 and 6 h after the insects were introduced. At a 15% concentration, EO with a 0 h pre-exposure period had significantly higher adult and larva mortalities after 6 h than those of 0.5, 1 and 2 h pre-exposure. Regardless of oil pre-exposure, insects were repelled, especially in test periods between 12 and 30 min. Therefore, grapefruit EO could be formulated for increased stability when an immediate impact is needed.

Potential for Using Four Plant Essential Oils to Protect Stored Products Against &lt;i&gt;Tribolium castaneum&lt;/i&gt; (Herbst) (Coleoptera: Tenebrionidae)

Food products that are kept in storage, such as grains, cereals, and processed foods, can sustain serious damage from stored-product insects. This study examined the effects of four essential oils (EOs) extracted from sweet violet (Viola odorata L.), parsley (Petroselinum crispum L.), neroli (Citrus aurantium amara), and marjoram (Origanum majorana) against red flour beetles Tribolium castaneum (L.) in terms of contact and fumigant toxicities, repellency, and antifeedant properties. The EOs of O. majorana and V. odorata had the highest contact toxicities against T. castaneum adults, with LC50 of 5,313 mg/L and 5,512 mg/L, respectively. The EO of V. odorata showed the highest fumigant toxicity against adults of T. castaneum with an LC50 of 491 mg/L after 48 hours of exposure. All tested EOs exhibited a repulsive effect against adults of T. castaneum. Rejection of the tested EOs increased with increasing concentrations and time of exposure, except for O. majorana. The lowest concentration of EOs extracted from P. crispum and O. majorana demonstrated feeding stimulatory effects over control, but C. aurantium showed the highest feeding deterrence index (FDI) value against adults of T. castaneum. The phagostimulant activity of O. majorana and P. crispum decreased linearly as the applied concentration of the EOs increased. The application of EOs resulted in a significant decrease in the number of emerged adults of new generation progeny (F1); the reduction in F1 exhibited a dose-dependent relationship. These findings highlight the prospective application of plant EOs as biocontrol agents against adults of T. castaneum.

Physicochemical comparison of chitin characteristics in three major stored-product beetle pests: Implications for biofumigant toxicity

The present study investigates the chitin properties of stored-product insect pests and their association with the fumigant toxicity of garlic essential oil. Chitin isolates of Callosobruchus maculatus, Sitophilus oryzae, and Tribolium castaneum adults were characterized using FT-IR, XRD, EA, SEM-EDS, and NMR techniques. Fumigant toxicity assay was performed under airtight condition in glass vial. The S. oryzae contains highest chitin content (19 %), followed by T. castaneum (10 %) and C. maculatus (8 %). The degree of crystallinity was lower in C. maculatus (67.13 %) than in S. oryzae (77.05 %) and T. castaneum (76.56 %). Morphologically, C. maculatus chitin displayed a flat lamellar surface with pores, while S. oryzae and T. castaneum exhibited densely arranged microfibrils based surfaces. Fumigant toxicity assays revealed varied susceptibility levels, C. maculatus exhibited higher susceptibility (0.27 μL/L air of LC50) compared to S. oryzae and T. castaneum (14.35 and 3.74 μL/L air of LC50, respectively) to garlic essential oil. The higher chitin content, greater crystallinity, and densely arranged structures in S. oryzae might contribute to its tolerance towards fumigant. Additionally, physico-chemical properties and penetration potentiality of the bioactive constituents might be linked to the toxicity in insects. Understanding these relations can enrich knowledge of chitin's role in fumigant toxicity mechanism.

Chemical composition, toxicity, and repellency of some Myrtaceae plants essential oils against Tribolium castaneum (Herbst)

Essential oils (EOs) obtained from plants have the potential to be environment-friendly alternatives to synthetic insecticides in agriculture. Tribolium castaneum (Herbst) is a cosmopolitan pest that causes the loss of a major proportion of stored crops. Therefore, we studied the insecticidal and repellent effects of EOs derived from the plants viz. Eucalyptus rudis, Eucalyptus crebra, and Melaleuca genistifolia against larvae and adults of T. castaneum. Essential oils were derived from the leaves of each plant using hydro-distillation. Gas chromatography-mass spectrometry (GC-MS) of the extracted EOs revealed that eucalyptol, viridiflorol, α-terpineol, and eugenol methyl comprised the major components of the EOs. However, the composition and quantity of the compounds varied across EOs. Specifically, EOs derived from E. rudis exhibited the highest fumigation toxicity against adult and larval T. castaneum, followed by M. genistifolia and E. crebra. In the presence of wheat grains, fumigation toxicity against T. castaneum declined by nearly threefold. Contact toxicity assays revealed that EOs from E. rudis were overall the most effective against the pest (LC50: 0.392 μL/cm2 for adult; LC50: 0.471 μL/cm2 for larva) followed by M. genistifolia (LC50: 0.424 μL/cm2 for adult; LC50: 0.478 μL/cm2 for larva) and E. crebra (LC50: 0.471 μL/cm2 for adult; LC50: 0.515 μL/cm2 for larva). The LC50 value of each EO was up to five times lower in adults than in larvae. Melaleuca genistifolia was the most effective repellent against T. castaneum adults; however, its effectiveness decreased with increasing exposure time. In conclusion, the EOs of E. rudis, E. crebra, and M. genistifolia were all viable green biopesticide alternatives to synthetic insecticides.

Efficacy of Four Insecticides Applied to Fortified Rice with Basil against Major Stored-Product Insect Species

Rice is one of the most important foods since it is grown in many countries and consumed by the majority of the population. Ensuring food security through the protection of stored-product commodities has become one of the most important priorities worldwide. In this study, the effects of three insecticidal formulations and an available diatomaceous earth formulation on basil-fortified rice against the major stored-product insects were evaluated. The label dose of each insecticidal formulation was used. Insect mortality was determined after 1, 3, 7, 14 and 21 days for each species. The entire experiment was repeated three times by preparing different lots of treated and untreated rice for each treatment. The results of the diatomaceous earth treatments showed that the most susceptible individuals were Sitophilus oryzae adults and Oryzaephilus surinamensis larvae, while the least susceptible individuals were Rhyzopertha dominica and Tribolium castaneum adults. The tested insecticides were effective against S. oryzae, as mortality was 100%. Between the two pyrethroids, deltamethrin was more effective than cypermethrin in the tested insecticides. Our findings indicate that there are available insecticides on the market which can be obtained successfully for the durable protection of agricultural commodities after the harvest stage.

Effect of α-cypermethrin and pirimiphos-methyl on wing morphology of Tribolium castaneum (Herbst) and T. confusum Jacquelin du Val: a comparative study

Tribolium castaneum (Herbst) and Tribolium confusum Jacquelin du Val (Coleoptera: Tenebrionidae) are widespread and serious pests of stored products. Various insecticides are applied aiming to effectively manage both species. Here, two insecticides are tested, the pyrethroid α-cypermethrin and the organophosphate pirimiphos-methyl, hypothesizing that they can lead to morphological changes in the certain body parts of the adult offspring of treated T. castaneum and T. confusum parental female adults. For this purpose, the geometric morphometric method to the elytra and hindwings was applied. Both males and females were included in the analysis. The results showed that adult individuals of T. confusum showed higher tolerance to both insecticides compared to T. castaneum adults. This finding is reflected in analyses of both pairs of wings in T. confusum where changes in shape were negligible. The hindwings of T. castaneum experienced deformations to both insecticides. More significant changes in wing shape were observed in the α-cypermethrin treatment compared to pirimiphos-methyl. In the case of T. castaneum, even the shortest exposure to insecticides (5 min) is enough to provoke shape changes in the hindwings. Deformities in offspring, caused after treatment of their parents with insecticides, could moderate the frequency of insecticidal applications in storages.

Evaluation of the Insecticidal Activity of Nerium oleander L. against the Red Flour Beetle, Tribolium castaneum (Herbst) (Tenebrionidae, Coleoptera)

Background: The red flour beetle, Tribolium castaneum (Herbst) (Tenebrionidae, Coleoptera) is a pest of worldwide distribution and can cause destructive damage to stored grains. The physicochemical properties and varied effects against insect pests make plant extracts a potential alternative in the development of pesticides. Methods: In this study, we assayed the oleander leaf extract toxicity effects against T. castaneum adults in the laboratory. We used four concentrations of Oleander methanol leaf extract. Result: Exposure of T. castaneum adult to the oleander leaf extracts produced 100% mortality in the insecticidal bioassay, especially at 40% concentration. The mortality % ranged from 13.3-100% after 48hrs. The mortality percentage of the red flour beetle adults decreased by increasing exposure periods. The mortality % was highly negatively correlated with exposure times (R= -0.97, P =.0001; R= -0.80 and P=.0001) at 40 and 20% concentrations, respectively. The overall results of the current study suggest that the leaf extract of Nerium oleander may possess potential insecticidal properties, which could potentially be employed in pest management. The infrared analysis of the oleander leaf extract showed many bioactive components associated with plant secondary metabolites; some of these identified phytochemical compounds have biological activity. Further, the phenol and flavonoid total were estimated. We conclude that the oleander leaf extract has the potential to be useful in managing stored grain insect pests, particularly T. castaneum, but that it must be handled and applied with extreme caution.

Comparative Analysis of the Metabolic Profiles of Strains of Tribolium castaneum (Herbst) Adults with Different Levels of Phosphine Resistance Based on Direct Immersion Solid-Phase Microextraction and Gas Chromatography-Mass Spectrometry

The management of phosphine (PH3) resistance in stored grain pests is an essential component of implementing timely and effective pest control strategies. The prevailing standard method for PH3 resistance testing involves the exposure of adult insects to a specific concentration over a fixed period. Although it is widely adopted, this method necessitates an extensive period for assay preparation and diagnosis. To address this issue, this study employed Direct Immersion Solid-Phase Microextraction (DI-SPME) coupled with Gas Chromatography-Mass Spectrometry (GC-MS) to compare and analyze the metabolic profiles of PH3-sensitive (TC-S), PH3 weak-resistant (TC-W), and PH3 strong-resistant (TC-SR) Tribolium castaneum (Herbst) adults. A total of 36 metabolites were identified from 3 different PH3-resistant strains of T. castaneum; 29 metabolites were found to present significant differences (p &lt; 0.05) across these groups, with hydrocarbon and aromatic compounds being particularly prevalent. Seven metabolites showed no significant variations among the strains, consisting of four hydrocarbon compounds, two iodo-hydrocarbon compounds, and one alcohol compound. Further multivariate statistical analysis revealed a total of three, two, and nine differentially regulated metabolites between the TC-S versus TC-W, TC-S versus TC-SR, and TC-W versus TC-SR groups, respectively. Primarily, these metabolites comprised hydrocarbons and iodo-hydrocarbons, with the majority being associated with insect cuticle metabolism. This study demonstrates that DI-SPME technology is an effective method for studying differentially expressed metabolites in T. castaneum with different levels of PH3 resistance. This approach may help to provide a better understanding of the development of insect PH3 resistance and act as a valuable reference for the establishment of rapid diagnostic techniques for insect PH3 resistance.

Evaluation of an eco-friendly botanical extract against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) and its composition

The red flour beetle, Tribolium castaneum (Coleoptera: Tenebrionidae), is one of the most damaging grain insect pests in the storage products industry. The acquired resistance to synthetic pesticides and the high toxicity of these compounds on non-target organisms have led to an increase in the search for biopesticides. Thus, the present study aimed to analyze, for the first time, the chemical composition of the extract of Crotalaria stipularia Desv. seeds and its insecticidal activity against T. castaneum adults. Therefore, the crude extract (5 % w/v) of C. stipularia seeds was performed in a 50 mM Tris − HCl pH 8.0. Lectin and secondary metabolites such as flavones, flavonols, xanthones and saponins were detected in the extract. The extract (10 % w/v) of C. stipularia caused 100 % mortality against T. castaneum insects and exhibited moderate deterrent activity, resulting in a 70 % reduction in food consumption compared to their normal intake. Furthermore, the aqueous extract exerted antinutritional effects, interfering with the metabolism of proteins, cholesterol, triglycerides and carbohydrates, and abolished the hatching of eggs of the treated insects. The phytotoxicity test revealed that the extract of C. stipularia is not toxic to non-target organisms, as it did not affect the germination of lettuce (Lactuca sativa) seeds. These results support the search for integrated management strategies for the control of T. castaneum using a new biomaterial obtained from C. stipularia seeds.

The component of the Chamaecyparis obtusa essential oil and insecticidal activity against Tribolium castaneum (Herbst)

Tribolium castaneum (Herbst) is a worldwide grain storage pest controlled by chemical control methods of phosphine fumigation, which results in many hazards, damages human health, makes pests resistant to pesticides, and pollutes the environment. In recent years, the popularity of botanical insecticides has continued to rise, and plant essential oils (EO) are considered potential alternatives for developing insecticides. In the current study, we selected the Chamaecyparis obtusa EO to determine its insecticidal effects and component analysis on T. castaneum. Through gas chromatography-ion mobility spectrometry (GC-IMS) technology, cedrol was the most obvious compound in the signal peak of the volatile components detected in the C. obtusa EO. The results of the bioassay showed that the C. obtusa EO had certain contact activity against T. castaneum, and the LD50 was 52.54 μg/adult. At three concentrations (0.41,1.62, 2.83 uL/cm2), the repellent rates of C. obtusa EO against T. castaneum were all above 80% at 15, 30, 60, and 120 min, respectively, indicating that the repellent effect was strong. Meanwhile, the C. obtusa EO exhibited fumigant toxicity against T. castaneum with LC50 values of 7.09 μg/L air. In addition, C. obtusa EO significantly increased the activity of AChE, CarE, POD, CAT, T-SOD, and chitinase in T. castaneum. Finally, the mechanism of C. obtusa EO on T. castaneum adults was explored based on transcriptome sequencing. We found that the DEGs focused on the chitin metabolic process and some aging genes in T. castaneum. Therefore, C. obtusa EO could be used as potential eco-friendly candidates for stored grain pest management.

Insight into the molecular mechanism of phosphine toxicity provided by functional analysis of cytochrome b5 fatty acid desaturase and dihydrolipoamide dehydrogenase in the red flour beetle, Tribolium castaneum

Phosphine is the dominant chemical used in postharvest pest control. Widespread and highly frequent use of phosphine has been selected for pest insects, including Tribolium castaneum, which is highly resistant. Lipid peroxidation and reactive oxygen species (ROS) are two major factors determining phosphine toxicity; however, the mechanisms of production of these two factors in phosphine toxicity are still unknown. Here, we first determined the time course of phosphine-induced lipid peroxidation and ROS production in T. castaneum. Our results showed that lipid peroxidation occurs before ROS in the process of phosphine toxicity, and fumigated beetles with higher resistance levels were associated with weaker activity on lipid peroxidation and ROS. A significant decline in lipid peroxidation was observed in fumigated individuals after knockdown of cytochrome b5 fatty acid desaturase (Cyt-b5-r) via RNA interference (RNAi), indicating that Cyt-b5-r is critical for triggering phosphine-induced lipid peroxidation. Moreover, significant decreases in both ROS and mortality were detected in fumigated T. castaneum adults fed melatonin for 7 days, an inhibitor of lipid peroxidation. Cyt-b5-r RNAi also inhibited ROS production and mortality in phosphine-treated beetles. Meanwhile, a significant decrease in ROS production (68.4%) was detected in dihydrolipoamide dehydrogenase (DLD) knockdown individuals with phenotypes susceptible to phosphine, suggesting that lipid peroxidation initiates ROS with the expression of DLD. However, a significant increase in ROS (122.1%) was detected in the DLD knockdown beetles with strongly resistant phenotypes, indicating that the DLD-involved pathway may not be the only mechanism of ROS generation in phosphine toxicity and the existence of a moonlighting role in downregulating ROS in strongly resistant T. castaneum.