Egg Stage Research Articles

Phytochemical properties and insecticidal activity of hexane extract of Melia azedarach fruit against Tuta absoluta (Meyrick)

The tomato leaf miner (TLM), Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), is important pest on tomato, potato and other Solanaceous with a huge economic importance. Management of the pest can be problematic, especially when the infestation pressure is high. Phytochemical and contact toxicity of the hexane extract of Melia azedarach L. (MA) fresh fruit on the developmental stage of egg, the 2nd larval instars and pupae of T. absoluta were evaluated in the laboratory condition, 27 ± 2 °C, 65 ± 5% relative humidity and 16 Light:8 Dark hours photoperiods. The findings showed that the hexane extract of M. azadrach is harmful to T. absoluta at various stages, including larvae and pupae. The major components in the extract were 9,12-Octadecadienoic acid (Z,Z)- methyl ester (69.375%), 9-Octadecenoic acid (Z)- methyl ester (17.231%) and Hexadecanoic acid, methyl ester (7.361%), respectively. Analysis of probit data showed that LC50 for MA extract on egg, 2nd instar larvae, and pupae were found to be 948.93, 346.72 and 1.75 μl/ml, respectively. Sublethal concentrations had significant impact on the nutrition of T. absoluta larvae (p < 0.001). The results showed that the extract controls T. absoluta in open and closed environments and is recommended for protecting the environment and the health of users.

A seasonal matrix population model for ixodid ticks with complex life histories and limited host availability.

Many vector-borne diseases are sensitive to changes in land use and climate; hence, it is important to understand the factors that govern the vector populations. Ixodid ticks, which serve as vectors for multiple diseases, have a slow life cycle compared with many of their hosts. The observable questing population represents only a fraction of the total tick population and may include overlapping cohorts in each stage. The duration of each life stage (larvae, nymph, and adult) is variable and depends on factors such as the seasonal timing of questing, development, and host availability. Mathematical models are therefore essential to mediate how complex life cycle transitions and host interactions underpin the seasonal dynamics of the questing tick population. In this study, we develop a seasonal matrix population model for ixodid ticks feeding on a small and large host. The model has 17 stages representing the main life history stages (eggs, larvae, nymphs, and adults) combined with status of feeding, seasonal timing of feeding, and overwintering. The probability of finding a host depends on tick instar and host type, and density regulation is incorporated through limited host capacity. Using a life history representing Ixodes ricinus in Northern Europe as a baseline, we extract seasonal numbers of different parts of the tick population and calculate life history outcomes such as generation time and mean and variance of lifespan and of lifetime reproductive output. These results are compared with an alternative scenario of a southern life history. Secondly, we investigate (1) effects of seasonality in the small host availability on the seasonal numbers of tick stages and (2) effects of varying host availability and utilization of small versus large hosts by larvae and nymphs, on the seasonal numbers of questing ticks. Our results suggest that the small host availability is an important regulating factor through the feeding of larvae. Our model incorporates complex mechanisms underlying the seasonal composition of the tick population. It can be applied to different ixodid tick species and provides a framework for future investigations into intra- and interspecific variation in life history and population dynamics.

Paternal Zinc Deficiency and Its Transgenerational Effects on Zinc Transporters in Drosophila.

The nutritional status of fathers plays a significant role in influencing the growth, metabolism, and susceptibility to diseases in their offspring. Paternal zinc deficiency can lead to developmental programming effects on the offspring's zinc homeostasis. This study investigated the effects of paternal zinc deficiency on the zinc homeostasis of offspring in a Drosophila melanogaster (fruit fly) model. Male flies were reared on a diet supplemented with a zinc-chelator, N,N,N',N'-Tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), from the egg stage until adulthood, and their offspring were subsequently reared on a normal diet for 7 d. Body zinc status and zinc transporters were assessed afterwards. The results indicated that the prenatal zinc deficiency significantly lowered total body zinc levels (p<0.05) compared to the controls. Additionally, the mRNA levels of zinc transporters, dZip42C.1, dZnT63C, and dZnT35C, were lower in the zinc-deficient male parents (p<0.05) and their male offspring (p<0.05). These findings suggested that paternal zinc deficiency can alter offspring zinc homeostasis, even when the offspring was fed a zinc-sufficient diet. This is an important finding, as zinc is an essential nutrient that is required for a variety of bodily functions. Further research is needed to better understand the mechanisms by which zinc deficiency in the male parent affects the health of the offspring and to develop strategies to prevent this from happening.

Response of Sitotroga cerealella and Trichogramma chilonis to gamma irradiation exposure

The present study was carried out to evaluate the response of gamma irradiation on Sitotroga cerealella and Trichogramma chilnois under laboratory conditions. Two different egg stages of S. cerealella, aged 12 and 24 hours, were exposed to four levels of gamma radiation (35, 55, 75 and 95 Gy) and control (no dose). The result indicates that low irradiation doses egg viability compared to higher doses. Exposure to 35 Gy resulted in the hatching rate (55.3%) and prolonged incubation period (7.06 days) for S. cerealella eggs. In T. chilonis, parasitism percentage was significantly higher at 86%, with maximum adult emergence at 87.3% and adult longevity of 7.13 days; however, these values remain lower than those observed in the untreated (control), where maximum parasitism, adult emergence and longevity were observed. The treatment with 95 Gy resulted in the lowest values for incubation, adult emergence, parasitism, and adult longevity. Irradiation of pupae also yielded significantly higher adult emergence (86.66%) and longevity 7.46 days at 5 Gy, pupae irradiated at 20 Gy resulted in significantly lower adult emergence and adult longevity. Based on these findings, lower irradiation doses are recommended to increase shelf life of S. cerealella and T. chilonis without causing significant detrimental effects on the quality of parasitoid and its host. The approach ensures the year around availability of parasitoids in insectaries for research and field releases.

Ovicidal Effect of Entomopathogenic Fungi on Emerald Ash Borer, Agrilus planipennis Fairmaire, Eggs

The emerald ash borer (EAB) is an invasive beetle that has killed hundreds of millions of ash trees throughout North America since its arrival. The use of entomopathogenic fungi as part of integrated pest management approaches is considered effective against a wide range of insect pests. The aim of this study was to screen and select locally adapted EAB-associated entomopathogenic fungi with ovicidal effect on EAB eggs under laboratory conditions. The pathogenicity of nine fungal strains, previously isolated from EAB galleries, and the commercial Beauveria bassiana strain GHA was tested. Three of these, Akanthomyces muscarius 48-27, Lecanicillium longisporum 66-14 Lecanicillium psalliotae 59-2, and GHA B. bassiana strain consistently showed significant ovicidal effects and a high percentage of inoculum recovery both from eggs and neonate larvae. The high levels of inoculum recovery from neonate larvae demonstrate that, even after emergence, larvae were infected. The possibility of disrupting EAB’s life cycle at the egg stage through microbial control represents a potential management opportunity that should be explored in future field studies. Future work should also study the effect of EPF on neonate larvae survival and performance. To our knowledge, this is the first study to evaluate the effect of entomopathogenic fungi against the egg stage of EAB.

Impact of Lactobacillus rhamnosus GG fermentation on shelf life of Volvariella volvacea paste

AbstractPaste formulations of Volvariella volvacea (VV) were developed for its shelf-life enhancement. Egg stage fruiting bodies of mushrooms were used for preparation of salted, spiced, and their fermented pastes. Fermented paste formulations were developed using inoculation with Lactobacillus rhamnosus GG at 0.5% (w/w) and incubation for 2 days at 35 ± 2 °C. The unfermented VV paste was preserved with sodium benzoate of 0.065%, while fermented formulations were kept devoid of any chemical preservative. All formulations were packed in glass jars and retort bags, and thereafter treated in boiling water bath for one hour. The spiced, fermented VV paste scored highest in sensory evaluation and maximum crude protein and moisture contents, while lowest in contents of ash, fat, crude fibre, and carbohydrates. The fermented (salted and spiced) VV pastes showed variation in pH at 4 °C. Shelf life of 56 days was observed for fermented VV paste stored in glass jars under refrigerated conditions. The antioxidant analysis revealed that DPPH radical scavenging activity of fermented paste formulations increased significantly up to 21 days followed by gradual decrease until the 56th day, while total phenolic content of all paste formulations decreased with storage time. Hence, fermented spiced paste showed enhanced nutritive and antioxidative potential and shelf life up to 56 days.

A framework for modelling desert locust population dynamics and large-scale dispersal.

There is an urgent need for mathematical models that can be used to inform the deployment of surveillance, early warning and management systems for transboundary pest invasions. This is especially important for desert locust, one of the most dangerous migratory pests for smallholder farmers. During periods of desert locust upsurges and plagues, gregarious adult locusts form into swarms that are capable of long-range dispersal. Here we introduce a novel integrated modelling framework for use in predicting gregarious locust populations. The framework integrates the selection of breeding sites, maturation through egg, hopper and adult stages and swarm dispersal in search of areas suitable for feeding and breeding. Using a combination of concepts from epidemiological modelling, weather and environment data, together with an atmospheric transport model for swarm movement we provide a tool to forecast short- and long-term swarm movements. A principal aim of the framework is to provide a practical starting point for use in the next upsurge.

Dissecting roles of pannier splice variants during pupal and adult morphogenesis in Henosepilachna vigintioctopunctata.

The GATA transcription factor gene, pannier (pnr), has been extensively studied in Drosophila, revealing its crucial role in dorsal closure, heart development and the regulation of cuticular bristle patterns in adults. However, studies on the functions of pnr in the development of coleopteran insects are still scarce. Herein, we identified the pnr gene in Henosepilachna vigintioctopunctata and discovered two splicing variants named Hvpnr-α and Hvpnr-β respectively. Temporal expression analysis revealed that Hvpnr, Hvpnr-α and Hvpnr-β were expressed at various stages including egg, larval, pupal and adult stages. To investigate the developmental role of Hvpnr in H. vigintioctopunctata, RNA interference (RNAi) assays were conducted on third-instar larvae. Injection of dsHvpnr, dsHvpnr-α and dsHvpnr-β and co-injection of dsHvpnr-α and dsHvpnr-β (dsRNAs mix) all resulted in significant downregulation of the target transcripts. In pupae developed from dsHvpnr-treated larvae, the symmetric black spots on both sides of the mesothorax, metathorax and tergites approached and connected. Pupal morphometric analysis revealed that dsHvpnr, dsHvpnr-α and dsRNAs mix injections significantly narrowed the spacing of dorsal symmetric spots, contracted spiracle distances on tergite sides, diminished pronotum width and markedly reduced inter-compound eye spacing compared to controls. In addition, injections of dsHvpnr and dsRNAs mix significantly reduced the oviposition in female adults. Silencing of Hvpnr led to the disappearance of the scutellum in adults, preventing the elytra from closing and properly attaching to the dorsal side of the abdomen. It is noteworthy that dsHvpnr-α or dsRNA mix induced scutellum formation defects in adults, while knockdown of Hvpnr-β had no impact. Furthermore, in stark contrast to previous studies on ladybird species such as Harmonia axyridis and Coccinella septempunctata, silencing Hvpnr did not affect melanin synthesis in pupae and adults in H. vigintioctopunctata. These findings demonstrate that among the splice variants of Hvpnr, Hvpnr-α plays a dominant regulatory role in the post-embryonic morphogenesis of H. vigintioctopunctata. This study also shows that Hvpnr is not involved in melanin synthesis, indicating significant functional differentiation of pnr during the evolution of ladybirds.

Dynamics of Natural Mortality Factors of Immature Diatraea saccharalis (Fabricius) (Lepidoptera: Crambidae) in Sugarcane Adjacent to Forest Fragments

ABSTRACTPest regulation may be favoured in crop fields adjacent to semi‐natural vegetation such as fragments of the Atlantic Forest in Southeastern Brazil. Therefore, the objective of this study was to analyse the dynamics of mortality factors for eggs and larvae of Diatraea saccharalis (Lepidoptera: Crambidae) in sugarcane adjacent to two types of forest fragments (Plateau and Gallery) at two distances from these fragments during two growing seasons. In each area (seven sugarcane plots), two 50 m long transects were established, parallel and spaced at 5 and 100 m from the field edge, and cohorts of the insect at each stage of development were monitored. The collected data were used to construct an ecological life table and determine the main mortality factors. Natural mortality factors that could not be characterised were grouped as unknown. In both seasons and stages of development observed, there was no difference in mortality between the two types of forest fragments (Plateau and Gallery) or between the two distances from the forest. For the egg stage, the mortality factors were classified as inviable due to infertility, predation, parasitism, desiccation and dislodgement. In both seasons, there was a significant difference in the natural mortality factors of D. saccharalis, with predation distinct from the others. Ants (Hymenoptera: Formicidae) and green lacewings (Neuroptera: Chrysopidae) were the most frequent predatory agents and occurred at both distances and types of forest fragments. For the larval stage, the mortality factors were classified as predation, parasitism, drowning and unknown, with the unknown group differing from the others. Unknown factors might have included predation, larval movement towards other plants and displacement caused by wind after hatching. Overall, predation is a key mortality component of D. saccharalis suppression. Therefore, agricultural practices focused on the conservation of natural enemies such as predators may provide more sustainable management.

Phosphine and phosphine plus ethyl formate for controlling papaya mealybug (Hemiptera: Pseudococcidae) on succulents.

The papaya mealybug, Paracoccus marginatus (Hemiptera: Pseudococcidae), poses a serious threat to global trade and is classified as a quarantine pest in some countries. Phosphine (PH3) is considered an alternative to methyl bromide for postharvest control of P. marginatus. However, reports addressing the impact of PH3 treatment to control P. marginatus on succulent plants are lacking. This study aims to investigate the effects of PH3 fumigation alone and in combination with ethyl formate (EF) on insecticidal activity across all developmental stages of P. marginatus and its influence on the quality of plant products. Tolerance tests showed that among all developmental stages, the egg stage of P. marginatus is the most tolerant to PH3 treatment. A concentration of 1g m-3 PH3 for 8h exposure at 25 °C achieved a 99.9968% (Probit-9) mortality rate for the eggs. Additionally, we examined the synergistic effects of combining EF with PH3. Combined fumigation with 0.5g m-3 PH3 and 2g m-3 EF for 8h at 25 °C did not adversely affect the lifespan and quality of three succulent plant species, achieving an effective dose of 0.99991. These findings suggest that PH3 fumigation, with or without EF, are effective treatments for postharvest control of P. marginatus in succulent plants.

RNAi-mediated knockdown of Gastric lipase gene response to spirobudiclofen stress in Panonychus citri

Panonychus citri is a globally distributed pest that is currently controlled using insecticides. However, alternative strategies are needed to minimize the use of chemicals. Given that the enormous potential of RNA interference pesticides in pest control development, lipases also have key roles in underpinning insect reproduction, development, defence from pathogens and oxidative stress, and pheromone signalling.Therefore, studying the function of Gastric lipase as a control measure for P. citri may be a promising approach. In this study, we cloned PcGTGL from the genome and studied its transcriptional response to spirobudiclofen, as well as its response after PcGTGL was knocked down. The results showed that the expression level of PcGTGL was higher during the larval、deutonymph and adult stage compared to the stage of egg. Additionally, under the stress of spirobudiclofen, the expression level decreased with the concentration of insecticides increased. We silenced PcGTGL through RNAi, and the results indicated an increase in mortality rate of P. citri, as well as a lethal phenotype characterized by body folding and darkening. Additionally, we found that treatment with spirobudiclofen on PcGTGL-silenced P. citri not only increased mortality rates and the mRNA expression of hormone-sensitivelipase(HSL), but also led to lower expression levels of PcGTGL、PcVg 、PcVgR and accumulation of TAG. These results indicate that the silencing of PcGTGL effectively inhibits the population growth of P. citri. Following the inhibition of PcGTGL, P. citri helps them obtain the energy needed to resist insecticide stress by triggering HSL action. The results provide a new RNAi-based target for control of P. citri.

Development of Idaea inquinata (Lepidoptera Geometridae) at different constant temperatures and relative humidities under controlled conditions

The rusty wave moth Idaea inquinata is an insect pest that infests dried herbs, above all when stored in warehouses. Infestations were historically localised, but the recent climatic change might increase the incidence of this pest in many areas of north Italy. The artificial regulation of the environmental conditions of warehouses is one of the most common techniques to control pests, often combined with thermal treatments just after the introduction of the stocks. The optimisation of the warehouse conditions, however, requires a deep knowledge on how the species react to variations in temperature and relative humidities. This information is to date missing for I. inquinata and this work aimed to fill this gap in knowledge. The life tables at 35% and 70% RH, and at different constant temperatures were obtained for the egg, larval, and pupal stages by combining datasets provided by 20 years of continuous rearing of this species. A second part of the study, instead, concerned the estimation of the parameters of the temperature-dependent development rate functions, laying the foundations for further formulations of mathematical models to be applied in decision support systems. Life tables showed that conditions of low relative humidities and low temperatures are a good compromise that slows down the development time of the preimaginal stages. The upper thermal limit for the development of this species, instead, is around 40 °C, a threshold that can be considered for further thermal treatments to disinfest warehouses before the introduction of pest-free stocks or as a controlling action in case of infestations.

Predation rates on flatback turtle Natator depressus eggs and hatchlings at an island rookery

Predation can significantly threaten the vulnerable egg and hatchling stages of sea turtles, yet for most populations this remains poorly quantified for use in conservation. We provided the first quantified predation rates of flatback turtle eggs and hatchlings at Thevenard Island, a medium-sized rookery on the northwest coast of Australia, with a focus on ghost crabs as potential predators. Burrow densities were used as proxy for ghost crab densities, while start- and end-of-season nest inventories and infrared videography were used to quantify egg and hatchling predation, respectively. Inventories of 27 nests suggested a mean hatching success of 74.2 ± 4.6% with zero predation of eggs, while videography at 17 nests indicated that 30.1 ± 8.1% of emerged hatchlings were predated, mainly by ghost crabs. Females selecting nest locations not easily accessible to ghost crabs, or the composition of flatback’s eggshells may explain the lack of egg predation. A 44.0% egg-to-surf survival rate was estimated, almost double the rate estimated for C. caretta on the Ningaloo coast (24.4%) using similar techniques. Further work is needed to understand if those predation rates are sustainable for recovering threatened species and if mitigation efforts tailored to each species and each life stage are needed.

Night-time light-traps and push–pull integrated system enhanced the control of different life stages of fall armyworm, Spodoptera frugiperda, (Lepidoptera: Noctuidae)

BackgroundMaize, Zea mays L (Cyperales: Poaceae), is one of the major cereal crops grown in Ethiopia for its food and feed values. Recently, the fall armyworm (FAW) (Spodoptera frugiperda) has become a major challenge of maize production threatening smallholder farmers in the country. Developing effective and smallholder farmers-friendly integrated pest management for FAW is vital. Therefore, a study was conducted to evaluate the effect of night-time light-traps and push–pull integrated system on controlling different life stages (adult, larvae and eggs) of FAW.MethodsThe study was conducted in Northern Ethiopia included four treatments; maize monocrop, maize plots with night-time light-trap, a push–pull system, and night-time light-trap and push–pull integrated system. Each treatment was replicated five times. The study was carried out twice involving a rain feed (from July to October 2018) and irrigated (from April to June 2019) experiments.ResultsA significantly greater number of FAW moths were captured on traps placed outside maize field plots treated with light-trap and push–pull integrated system than traps placed outside the maize monocrop, light-trap alone and push–pull alone treated plots during the 2018 and 2019 experiment seasons. As a result, a significantly lower number of moths was found inside maize field plots treated with light-trap and push–pull integrated system than the other treatments. The levels of FAW eggs and larval infestation were significantly lower in maize plots treated with the light-trap and push–pull integrated system than the maize monocrops, push–pull alone, and light-trap alone treated plots. The proportion of plants damaged by FAW larvae was significantly lower in maize plots treated with the light-trap and push–pull integrated system relative to maize plots treated with the other treatments.ConclusionThis study proved that a system integrating night-time light-traps and push–pull results in better and more effective control of different stages of FAW than a push–pull system or night-time light-traps alone.

Population structure and feeding habits of Carcinoscorpius rotundicauda in the bay environment, Southern Gulf of Thailand

This study presents the first comprehensive assessment of the population structure and feeding habits of Carcinoscorpius rotundicauda in Thailand. Sample collection was conducted using crab gill nets at seven sampling sites characterized by distinct ecosystem attributes in Pattani Bay between February 2019 and March 2020. Our findings indicate the presence of a single Asian horseshoe crab (HSC) species within the bay, with a sex ratio of approximately 1:1 (48.1 % males, 51.9 % females) that did not deviate significantly from parity. Habitat variation within the bay did not influence HSC abundance (P > 0.05) whereas monthly abundance fluctuations were highly significant (P < 0.001), peaking in March and reaching the lowest in September. Positive correlations were observed between HSC abundance and environmental factors including dissolved oxygen, temperature, water pH, water depth, and chlorophyll c concentrations. Linear regression analysis revealed a positive correlation between morphometric characteristics and body weight. However, multiple linear regression analysis indicated a negative relationship between body weight and telson length (TEL) and opisthosoma width (OW) of males, as well as TEL of females. The size at which 50 % of the HSC population reached maturity (L50) was estimated to be 12.2 cm for males and 13.5 cm for females based on prosomal width (PW). The average PW measurements of HSC at different egg stages (1–4) from developing to mature females was 14.4 cm, with corresponding body weights ranging from 224 to 243 g. Females at egg of stages 3 and 4 were found throughout the year, indicating multiple spawning events, particularly prevalent in January-April, and predominantly abundant at stations 1, 2, 5 and 6. HSC primarily consumed bivalves (22.1±21.2 %), followed by fishes (5.9±13.0 %) and crustaceans (2.9±9.0 %) by volumetric contribution (%V). This comprehensive study provides novel insights into the population dynamics and feeding ecology of HSC within Thailand. The findings establish a foundational framework for future research endeavors and offer critical data to inform the management and conservation of their habitats.

Monitoring of mosquito breeding sites in the municipality of Cascais, Portugal

Abstract Culex pipiens is the primary West Nile Virus vector in Portugal. Additionally, in 2017, Aedes albopictus, vector of various arboviruses, was detected in Northern Portugal. To mitigate viral transmission risks, effective surveillance is crucial, including monitoring egg, larva, and pupa stages. Located on the west of Lisbon, Cascais implemented a surveillance based on monitoring invasive species at Points of Entry and, complementarily, on detecting and intervening in breeding sites. Active searches for new breeding sites and monitoring those that were already identified are conducted weekly during the peak mosquito season (May to October) and biweekly during the colder season (November to April), following the methodology outlined below: • Upon detection, samples of immature stages are collected for submission to the National Institute of Health (INSA); • Corrective measures are requested to the managing entities of the locations where the sites are found; • Date of action, location, collection point, date of report, and status (pending or intervened) are recorded on a database; • Locations with pending status undergo continuous monitoring. In 2023, 16 artificial breeding sites were identified. These findings resulted from 23 actions conducted across 8 locations. 35 samples of immatures were collected, followed by their submission and notification to the respective managing entities. Recurrent detections were noted in 9 breeding sites. The managing entities implemented measures at 13 of the identified sites, leaving 3 with pending intervention. The identification of breeding sites demands continuous monitoring efforts and requires an effective coordination between the Public Health services and the management entities. Based on the achieved outcomes, it is evident that the implementation of corrective measures has been successful, making a significant contribution to reducing mosquito density. Key messages • Effective surveillance and intervention strategies are crucial in mitigating West Nile Virus and arbovirus transmission risks in Portugal. • Continuous monitoring and coordination between public health services and management entities are key for maintaining effective vector control measures.

Hyperosmolality tolerance of freshwater largemouth bass Micropterus salmoides to brackish in early ontogenetic stages of eggs, embryos, and yolk-sac larvae

Hyperosmolality tolerance of freshwater largemouth bass Micropterus salmoides to brackish in early ontogenetic stages of eggs, embryos, and yolk-sac larvae

Volatile Organic Compounds as Early Detection Indicators of Wheat Infected by Sitophilus oryzae.

The rice weevil, Sitophilus oryzae (L.), is a major pest that poses a considerable threat to grain safety storage. Early detection is of great significance in reducing grain losses. Studies have demonstrated that pest infestation causes alterations in grain volatiles, potentially indicating the presence of pests. In this study, we detected volatile organic compounds (VOCs) in non-infected and pest-infected wheat on the 3rd, 9th, 17th, 22nd, and 40th days, corresponding to the developmental stages of the rice weevil at the egg, young larval, old larval, pupal, and adult stages, respectively. A total of 126 VOCs were identified, including 96 hydrocarbons, 7 alcohols, 5 aldehydes, 9 ketones, 9 esters, and 18 other compounds, 62 of which are newly produced compared to non-infected wheat. Six characteristic volatiles, namely dodecane, pentadecane, hexadecane, heptadecane, 2, 6, 10-trimethylpentadecane, and squalene, may be related to the degradation of lipids and the expression of wheat stress tolerance and underwent significant changes as infestation progressed, according to the VIP value. This study assists in interpreting the effects of rice weevil infestation on wheat at the metabolic level and establishes a foundation for storage inspection based on VOC analysis.

Regulation Mechanisms of the Glutamate Transporter in the Response of Pacific Oyster upon High-Temperature Stress.

Glutamate transporters (GLTs) are integral to the glutamatergic system, modulating glutamate homeostasis to enhance resilience and resistance against environmental stress. There are six GLTs identified in the Pacific oyster (Crassostrea gigas), which were categorized into two subfamilies: excitatory amino acid transporters (CgEAATs) and vesicular glutamate transporters (CgVGLUTs). The CgEAATs harbor a GltP domain, while CgVGLUTs feature an MFS domain, both with conserved sequence and structural characteristics. The expression of CgGLTs is elevated during the planktonic larval stage compared to the fertilized egg stage and is constitutively expressed in various tissues of adult oysters, suggesting its critical role in both larval development and the physiological processes of adult oysters. Transcriptomic analysis revealed diverse expression patterns of GLTs in oyster gills after 7 days of high-temperature stress, with CgEAAT3 showing a significant upregulation. A KEGG pathway enrichment analysis identified glutathione metabolism and ferroptosis as prominently enriched pathways. At 48 h after high-temperature stress, the expression levels of Glutathione Peroxidase 4 (CgGPX4) and CgEAAT3, along with elevated Fe content in the gills, significantly increased. Moreover, the RNAi-mediated the inhibition of CgEAAT3 expression under high-temperature stress, resulting in a significant reduction in CgGPX4 expression and a further increase in Fe accumulation in oyster gills. These results indicate that CgEAAT3 contributes to the regulation of ferroptosis and redox homeostasis by modulating CgGPX4 expression. This study provides new insights into the adaptive mechanisms of bivalves to environmental stress.

Thermal Stress as a Critical Factor in the Viability and Duration of Spittlebug Eggs

The spittlebug Mahanarva spectabilis (Distant, 1909) (Hemiptera: Cercopidae) is an important pest that causes significant losses in the production of forage crops for cattle feed. Information on the thermal requirements of this insect during the egg stage is crucial in assessing the interaction between insects and forage. The aim of this research was to evaluate the effects of constant and oscillating (diurnal/nocturnal) temperatures on the viability of M. spectabilis eggs and the duration of the egg stage. Temperatures of 20 °C to 30 °C were ideal for the development of this insect pest, resulting in greater viability and faster development of the embryos. In addition, it should be noted that a variation of up to 8 days is feasible for synchronizing the phenological stages of the forage plants and the eggs to be laid on these plants when subjected to 30 °C (16.6 days) or 20 °C (25.7 days) without significantly altering the viability of the eggs. Notably, a temperature oscillation of 25 °C during the day and 15 °C at night increased the viability of the eggs after exiting diapause. These results are essential for the rearing of M. spectabilis in the laboratory, allowing for the supply of eggs for experiments and contributing to advances in studies aimed at developing effective integrated management strategies for this pest.