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Helicoverpa armigera Hübner (Lepidoptera: Noctuidae; Hübner) is the major insect pest of pigeon pea [Cajanus cajan; Fabales: Fabaceae; (L.) Millspaugh] worldwide. Research to develop pest management strategies for H. armigera in pigeon pea has focused heavily on developing less susceptible cultivars, with limited practical success. We examined how pigeon pea crop stage influences plant susceptibility to H. armigera using a combination of glasshouse and laboratory experiments. Plant phenology significantly affected oviposition with moths laying more eggs on flowering and podding plants but only a few on vegetative plants. Larval survival was greatest on flowering and vegetative plants, wherein larvae mostly chose to feed inside flowers on flowering plants and on the adaxial surface of expanding leaves on vegetative plants. Larval survival was poor on podding plants despite moths laying many eggs on plants of this stage. When left to feed without restriction on plants for 7 days, larvae feeding on flowering plants were >10 times the weight of larvae feeding on plants of other phenological stages. On whole plants, unrestricted larvae preferred to feed on pigeon pea flowers and on expanding leaves, but in no-choice Petri dish assays H. armigera larvae could feed and survive on all pigeon pea reproductive structures. Our results show that crop stage and the availability of flowers strongly influence pigeon pea susceptibility to H. armigera. An increased understanding of H. armigera-pigeon pea ecology will be useful in guiding the development of resistant varieties and other management tactics.
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Cajanus , Helicoverpa armigera , Animales , Femenino , Helicoverpa armigera/fisiología , Herbivoria , Larva/fisiología , OviposiciónRESUMEN
In Australia, Soldier flies (Inopus spp.) are economically significant pests of sugarcane that currently lack a viable management strategy. Despite various research efforts, the mechanisms underlying the damage caused by soldier fly larvae remain poorly understood. Our study aims to explore whether this damage is associated with the transmission of plant viruses during larval feeding. We also explore the larval transcriptome to identify any entomopathogenic viruses with the potential to be used as biocontrol agents in future pest management programs. Seven novel virus sequences are identified and characterised using de novo assembly of RNA-Seq data obtained from salivary glands of larvae. The novel virus sequences belong to different virus families and are tentatively named SF-associated anphevirus (SFaAV), SF-associated orthomyxo-like virus (SFaOV), SF-associated narna-like virus (SFaNV), SF-associated partiti-like virus (SFaPV), SF-associated toti-like virus (SFaTV-1 and SFaTV-2) and SF-associated densovirus (SFaDV). These newly identified viruses are more likely insect-associated viruses, as phylogenetic analyses show that they cluster with other insect-specific viruses. Small RNA analysis indicates prominent peaks at both 21 nt and 26-29 nt, suggesting the activation of host siRNA and piwiRNA pathways. Our study helps to improve understanding of the virome of soldier flies and could identify insect viruses for deployment in novel pest management strategies.
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Dípteros , Perfilación de la Expresión Génica , Larva , Filogenia , Saccharum , Animales , Larva/virología , Dípteros/virología , Australia , Saccharum/virología , Transcriptoma , Virus de Insectos/genética , Virus de Insectos/clasificación , Virus de Plantas/genética , Virus de Plantas/clasificación , Genoma ViralRESUMEN
Despite substantial research examining caterpillar-plant interactions, changes in the feeding behaviour of lepidopteran larvae as they develop are poorly understood. In this study, we investigated ontogenetic changes in the behaviour of Helicoverpa armigera larvae feeding on reproductive structures of pigeonpea (Cajanus cajan). Specifically, we examined the preference for and avoidance of pigeonpea flowers and pods of first, second, third, and fourth instar H. armigera larvae. We also conducted a no-choice assay to compare the ability of third and fourth instar larvae to penetrate pigeonpea pod walls, which act as a physical defence against herbivory. When presented with a choice between pigeonpea pods and flowers, different instars behaved differently. First and second instar larvae largely avoided pigeonpea pods, instead feeding on flowers; third instar larvae initially avoided pods, but by 24 h, did not strongly discriminate between the structures; and fourth instars demonstrated a preference for pods. When initially placed on pods, first instars were slower than other instars to leave these structures, despite pods being suboptimal feeding sites for small caterpillars. We identified a clear instar-specific ability to penetrate through the pod wall to reach the seeds. Most third instar larvae were unable to penetrate the pod wall, whereas most fourth instars succeeded. Third instars suffered a physiological cost (measured by relative growth rate) when boring through the pod wall, which was not observed in fourth instars. Our study further illuminates the insect-plant interactions of the H. armigera-pigeonpea system and provides evidence for the significant changes in feeding behaviour that may occur during lepidopteran larval development.
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Islands offer exclusive prisms for an experimental investigation of biodiversity x ecosystem function interplay. Given that species in upper trophic layers, e.g., arthropod predators, experience a comparative disadvantage on small, isolated islands, such settings can help to clarify how predation features within biotic resistance equations. Here, we use observational and manipulative studies on a chain of nine Indonesian islands to quantify predator-mediated biotic resistance against the cassava mealybug Phenacoccus manihoti (Homoptera: Pseudococcidae) and the fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). Across island settings, a diverse set of generalist lacewing, spider and ladybeetle predators aggregates on P. manihoti infested plants, attaining max. (field-level) abundance levels of 1.0, 8.0 and 3.2 individuals per plant, respectively. Though biotic resistance-as imperfectly defined by a predator/prey ratio index-exhibits no inter-island differences, P. manihoti population regulation is primarily provided through an introduced monophagous parasitoid. Meanwhile, resident predators, such as soil-dwelling ants, inflict apparent mortality rates up to 100% for various S. frugiperda life stages, which translates into a 13- to 800-fold lower S. frugiperda survivorship on small versus large islands. While biotic resistance against S. frugiperda is ubiquitous along the island chain, its magnitude differs between island contexts, seasons and ecological realms, i.e., plant canopy vs. soil surface. Hence, under our experimental context, generalist predators determine biotic resistance and exert important levels of mortality even in biodiversity-poor settings. Given the rapid pace of biodiversity loss and alien species accumulation globally, their active conservation in farmland settings (e.g., through pesticide phasedown) is pivotal to ensuring the overall resilience of production ecosystems.
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Topical applications of insecticides ß-cyfluthrin, imidacloprid, and spinosad in combination with Beauveria bassiana (topical and contact filter paper application) induced synergistic interactions in lesser mealworm larvae, increasing mortality and in some cases numbers of larval cadavers exhibiting conidiogenesis. Reduced concentrations (LC10, LC20, LC30) of the insecticides induced sublethal effects in lesser mealworm larvae, inhibiting development (mass, head-capsule width, moulting) after eight days' exposure and movement behaviour (area explored and distance travelled) after 3 h' exposure. The most potent synergist was ß-cyfluthrin, it strongly inhibited larval development and movement while significantly increasing mortality and conidiogenesis in B. bassiana-infected larvae. Imidacloprid also strongly inhibited larval development and movement, but only produced weak short-lived synergistic increases in mortality, with no increase in conidiogenesis. Spinosad induced no effect on development and limited effect on movement, but still induced moderate short-lived synergistic increases in mortality and conidiogenesis. Intoxicated larvae exposed to B. bassiana on filter paper for 3 h showed no synergistic interactions, except when intoxicated by spinosad.
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Ascomicetos , Beauveria , Escarabajos , Hypocreales , Insecticidas , Tenebrio , Animales , Insecticidas/farmacología , LarvaRESUMEN
Landscape-scale factors known to influence in-field abundance of pest herbivores and their natural enemies, but little is known about effects that operate through the shorter-range influences exerted by habitats immediately adjacent to crop fields.This study first compared the abundance of brassica insect pests and their natural enemy arthropods in 24 spatially independent brassica vegetable fields across southern Australia. An 'edge effect' index was used to compare the abundance of each taxon in the field center with abundance in areas of the crop adjacent to differing habitats. Then, three landscape properties: landscape composition, edge density, and connectivity of diverse crop and non-crop habitats were analyzed at five scales up to 5 km from these focal field centers to assess longer-range influences on arthropod abundances in field centers and on the edge effects.Edge effect of adjacent woody vegetation promoted ladybirds and reduced diamondback moth and whiteflies. Conversely, the presence of crops and pastures immediately adjacent to focal crop fields reduced whiteflies and aphids but with no effect on natural enemies.Effect of landscape composition and connectivity on arthropod abundance at field center found promotion of aphids (cabbage aphid and green peach aphid) by woodland in the landscape.Effect of landscape properties on the edge effects of adjacent habitats was contrasting; strengthened (landscape composition and edge density on edge effect of crops, pasture and woody vegetation in reducing diamondback moth and whiteflies) as well as weakened (edge density and landscape connectivity on edge effect of crops, pasture and woody vegetation in reducing diamondback moth on diamondback moth, whiteflies and aphids, and promoting ladybirds). Synthesis and applications: Findings of this geographically extensive study help define the level of pest risk associated with sites as well as suggest potential interventions such as establishment or restorations of woody vegetation adjacent to crop fields that could reduce risk.
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Temperature has fundamental influences on the performance and distribution of insects. While considerable attention has been devoted to extreme conditions, particularly extreme cold conditions, few studies have investigated effects of mild cold conditions on insects. We examined the transcriptomic changes in mid-fourth instar larvae of both sexes reared at 10 °C and 25 °C to investigate sex-dependent responses of Plutella xylostella to mild cold stress. There were 624 differentially expressed genes (DEGs) in females, the majority of which (n = 386) were down-regulated. In males 3239 genes were differentially expressed and the majority (n = 2341) were up-regulated. Only 280 DEGs were common to both sexes. In females, there were no DEGs encoding heat shock or cold shock proteins, but six of these DEGs were found in males. These differences suggest that females and males might adopt some different strategies to cope with cold stress and/or that they were affected by rearing under cold conditions to different degrees and in different ways. In addition, DEGs encoding antimicrobial peptides, cytochrome P450 monooxygenases, fatty acid-related enzymes, cuticle proteins, myofilament, and hormone-related proteins were found in both sexes under cold stress. The transcriptome study reveals unexpected sex-dependent thermal responses and provides new information of how an insect that does not diapause copes with low temperatures.
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Mariposas Nocturnas , Femenino , Masculino , Animales , Mariposas Nocturnas/genética , Transcriptoma , Respuesta al Choque por Frío , Larva/genética , Perfilación de la Expresión GénicaRESUMEN
The Social Emotional Health Survey-Secondary-2020 (SEHS-S-2020) is a well-studied option for assessing social emotional health to support students within a multitiered system of school support. While a growing body of literature supports the SEHS-S-2020 measure for assessing student covitality, there is less validation evidence specifically for middle-school-aged students. The present study aimed to fill this gap in the literature by examining its use for younger adolescents. Study participants were from two samples, including a cross-sectional sample with 9,426 students in Grades 7-8 from 32 counties in California and a longitudinal sample with 414 students in Grades 6-8 from two middle schools. Data analyses examined structural validity, internal consistency, measurement invariance, criterion validity, predictive validity, and response stability. Results indicate excellent fit indices for a four-level higher-order measurement model, with adequate concurrent and one-year predictive validity coefficients, supporting the use of the SEHS-S-2020 measure with young adolescents in middle school settings. The discussion focuses on implications for assessing students' psychosocial assets, universal school-based screening, and cultural and intersectionality considerations when interpreting SEHS-S-2020 responses. Supplementary Information: The online version contains supplementary material available at 10.1007/s40688-022-00411-x.
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BACKGROUND: Helicoverpa armigera is a major pest of pigeonpea (Cajanus cajan). Efforts to develop pigeonpea varieties resistant to H. armigera attack have been met with limited success, despite reports of high levels of resistance to H. armigera in wild relatives of pigeonpea and reports of low to moderate levels of resistance in cultivated varieties. Here we examined H. armigera oviposition preference and larval performance on whole plants of three cultivars of short-duration pigeonpea: a susceptible control (ICPL 87) and two cultivars with purported host-plant resistance (ICPL 86012 and ICPL 88039). RESULTS: In our no-choice oviposition experiment, H. armigera laid similar numbers of eggs on all three cultivars tested, but under choice conditions moths laid slightly more eggs on ICPL 88039. Larval growth and development were affected by cultivar, and larvae grew to the largest size (weight) and developed fastest on ICPL 86012. Moths laid most of their eggs on floral structures, sites where subsequent early instar larvae overwhelmingly fed. Experimentally placing neonate larvae at different locations on plants demonstrated that larvae placed on flowers experienced greater survival, faster development, and greater weight gain than those placed on leaves. The type and density of trichomes (a potential resistance trait) differed among cultivars and plant structures, but larvae selected to feed at sites where trichomes were absent. CONCLUSION: Future work examining host-plant resistance against H. armigera should incorporate the behavioural preference of moths and larvae in experiments using whole plants as opposed to bioassays of excised plant parts in Petri dishes. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Cajanus , Mariposas Nocturnas , Animales , Femenino , Cajanus/química , Larva , Plantas , HerbivoriaRESUMEN
When an invasive species first breaches quarantine and establishes in yet another country, it invariably causes consternation for growers, in part because of incomplete understanding of the plants that are at risk. The Fall Armyworm, Spodoptera frugiperda (J.E. Smith) is the most recent example in Australia. The number of plants that this polyphagous noctuid is reported to attack is vast, including many crop species. Consequently, initial reactions from grower industry groups that perceived themselves at risk were to demand emergency use of insecticides. Yet the field evidence suggests that many crops might not be at risk and since S. frugiperda arrived in Australia, maize crops have suffered most damage, followed by sorghum. We question the accuracy of some of the claims of reported host plants of S. frugiperda and report experiments that compared oviposition behavior, neonate silking behavior, and larval performance on five crops: the known hosts maize and sorghum, and the putative hosts cotton, peanut, and pigeon pea. Maize ranked highest in all preference and performance measures, followed by sorghum and peanut, with pigeon pea and cotton ranking lowest. Although S. frugiperda can survive, develop, and pupate on the crop species we examined, cotton and pigeon pea are not preferred by the pest in either the larval or adult stages. We suggest that before a plant is listed as a host for a given insect that the evidence should be fully reported and carefully evaluated. Collecting an immature insect from a plant does not make that plant a host!
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Mariposas Nocturnas , Oviposición , Femenino , Animales , Spodoptera , Larva , Zea maysRESUMEN
We evaluated the virulence of Beauveria bassiana and Metarhizium isolates from soil collected across different vegetation types in Queensland, against chlorantraniliprole-resistant and insecticide-susceptible diamondback moth (DBM) larvae. Host insecticide resistance status had no effect on susceptibility to the pathogens when conidia were topically applied to larvae in the laboratory, and one B. bassiana isolate was significantly more virulent to larvae than the others (seven days after inoculation). The influence of temperature (15, 20, 25 or 30 °C): (i) at the point of host inoculation with conidia and (ii) when the pathogens had already initiated infection and were proliferating in the host haemocoel, was determined experimentally for its influence on virulence, disease progression, and sporulation. Temperature at inoculation had a greater effect on host insect mortality than it did when the fungus was already proliferating in the host haemocoel. The rearing temperature of hosts prior to inoculation had a greater effect on host susceptibility to disease than starvation of the larvae at the time of inoculation. Our results also show that each fungal isolate has its own temperature relations and that these can vary considerably across isolates, and at different points in the pathogen life cycle (germination and cuticular penetration versus growth in the host haemocoel). Temperature also had an idiosyncratic effect, across isolates and across the variables typically used to assess the potential of fungal entomopathogens as biological control agents (time to death, mortality and sporulation rates). This study demonstrates that in addition to pathogenicity and virulence, the temperature relationships of each fungal isolate when infecting insects needs to be taken into account if we are to understand their ecology and use them effectively in pest management.
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Beauveria , Insecticidas , Mariposas Nocturnas , Animales , Agentes de Control Biológico , Ecosistema , Insectos , Larva/microbiología , Mariposas Nocturnas/microbiología , Control Biológico de Vectores/métodos , Suelo , Esporas Fúngicas , TemperaturaRESUMEN
[This corrects the article DOI: 10.1016/j.cris.2021.100015.].
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BACKGROUND: An optimal starting point for relating genome function to organismal biology is a high-quality nuclear genome assembly, and long-read sequencing is revolutionizing the production of this genomic resource in insects. Despite this, nuclear genome assemblies have been under-represented for agricultural insect pests, particularly from the order Coleoptera. Here we present a de novo genome assembly and structural annotation for the coconut rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae), based on Oxford Nanopore Technologies (ONT) long-read data generated from a wild-caught female, as well as the assembly process that also led to the recovery of the complete circular genome assemblies of the beetle's mitochondrial genome and that of the biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). As an invasive pest of palm trees, O. rhinoceros is undergoing an expansion in its range across the Pacific Islands, requiring new approaches to management that may include strategies facilitated by genome assembly and annotation. RESULTS: High-quality DNA isolated from an adult female was used to create four ONT libraries that were sequenced using four MinION flow cells, producing a total of 27.2 Gb of high-quality long-read sequences. We employed an iterative assembly process and polishing with one lane of high-accuracy Illumina reads, obtaining a final size of the assembly of 377.36 Mb that had high contiguity (fragment N50 length = 12 Mb) and accuracy, as evidenced by the exceptionally high completeness of the benchmarked set of conserved single-copy orthologous genes (BUSCO completeness = 99.1%). These quality metrics place our assembly ahead of the published Coleopteran genomes, including that of an insect model, the red flour beetle (Tribolium castaneum). The structural annotation of the nuclear genome assembly contained a highly-accurate set of 16,371 protein-coding genes, with only 2.8% missing BUSCOs, and the expected number of non-coding RNAs. The number and structure of paralogous genes in a gene family like Sigma GST is lower than in another scarab beetle (Onthophagus taurus), but higher than in the red flour beetle (Tribolium castaneum), which suggests expansion of this GST class in Scarabaeidae. The quality of our gene models was also confirmed with the correct placement of O. rhinoceros among other members of the rhinoceros beetles (subfamily Dynastinae) in a phylogeny based on the sequences of 95 protein-coding genes in 373 beetle species from all major lineages of Coleoptera. Finally, we provide a list of 30 candidate dsRNA targets whose orthologs have been experimentally validated as highly effective targets for RNAi-based control of several beetles. CONCLUSIONS: The genomic resources produced in this study form a foundation for further functional genetic research and management programs that may inform the control and surveillance of O. rhinoceros populations, and we demonstrate the efficacy of de novo genome assembly using long-read ONT data from a single field-caught insect.
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Escarabajos , Secuenciación de Nanoporos , Nudiviridae , Animales , Escarabajos/genética , Femenino , Secuenciación de Nucleótidos de Alto Rendimiento , Perisodáctilos/genética , FilogeniaRESUMEN
In Australia, soldier flies are major pests of sugarcane, and they can cause significant yield losses in some areas, possibly due to the virus' transmission to the plants. We sequenced fly larvae salivary glands and identified a novel jingmenvirus, putatively named Inopus flavus jingmenvirus 1 (IFJV1). Phylogenetic trees confirmed that IFJV1 groups with insect-associated jingmenviruses, newly identified flavivirus-like viruses with a segmented genome. After the design and the validation of molecular detection systems for IFJV1, larval homogenates were passaged on insect and vertebrate cells, but IFJV1 could only be detected in the first two passages in insect cells and not at all in vertebrate cells. Despite this lack of consistent replication in laboratory models, this virus does replicate in its host Inopus flavus, as sequenced, small RNA from the larvae matched the IFJV1 sequences. Moreover, they were found to be predominantly 21 nucleotides long and map to the whole sequences on both strands, which is typical of an actively replicating virus. This discovery confirms the worldwide presence of jingmenviruses which, until now, had only been detected on four continents. However, the study of IFJV1 tropism and the possible pathogenicity to its host or the sugarcane it parasitizes requires the development of a stable replication model.
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Dípteros , Saccharum , Animales , Australia , Dípteros/genética , Larva , FilogeniaRESUMEN
Canegrubs (Coleoptera: Scarabaeidae) are major pests of sugarcane crops in Australia, but despite long-term and intensive research, no commercially viable biological control agents have been identified. We used the RNA-Seq approach to explore the viriomes of three different species of canegrubs from central Queensland, Australia to identify potential candidates for biological control. We identified six novel RNA viruses, characterized their genomes, and inferred their evolutionary relationships with other closely related viruses. These novel viruses showed similarity to other known members from picornaviruses, benyviruses, sobemoviruses, totiviruses, and reoviruses. The abundance of viral reads varied in these libraries; for example, Dermolepida albohirtum picorna-like virus (9696 nt) was built from 83,894 assembled reads while only 1350 reads mapped to Lepidiota negatoria beny-like virus (6371 nt). Future studies are essential to determine their natural incidence in different life stages of the host, biodiversity, geographical distributions, and potential as biological control agents for these important pests of sugarcane.
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Escarabajos , Virus ARN , Saccharum , Animales , Australia , Agentes de Control Biológico , Queensland , TranscriptomaRESUMEN
Social support is empirically linked to improved adolescent psychological and academic functioning. This study explored typologies characterized by family, peer, and school support among students in early (Grade 7; nâ¯=â¯27,399) and late (Grade 11; nâ¯=â¯27,984) adolescence. We assessed how each latent profile related to key aspects of psychological and academic functioning and the moderation of gender in these associations. Three convergent profiles (i.e., High, Moderate, and Low Support) and two divergent profiles (i.e., Minimum Peer Support and Minimum Family Support) were found in both grade levels, with psychological and academic functioning differentiated by the profiles. The Minimum Peer Support and Minimum Family Support profiles showed the lowest functioning in all domains across grade levels. The High Support profile showed the highest psychological health and academic performance. Gender moderation was observed in the associations between social support profiles and psychological functioning and was more prominent among 7th graders than 11th graders. Findings suggest that social support's impact is determined by combinations of various support sources, age, and gender. The social support profiles and their associations with students' characteristics and outcomes may inform practitioners in supporting vulnerable groups and planning interventions.
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Conducta del Adolescente , Apoyo Social , Adolescente , Conducta del Adolescente/psicología , Humanos , Grupo Paritario , Instituciones Académicas , Estudiantes/psicologíaRESUMEN
The leaf-mining moth, Stomphastis thraustica (Meyrick, 1908) was imported to Australia as a potential biological control agent of an exotic weed, bellyache bush (Jatropha gossypiifolia), from Peru. The insect colony has been maintained in the quarantine facility for over eight years but recently, significant mortality was observed in the culture. The larvae demonstrated swollen intersegments with a fragile integument. The infected larvae are cloudy muted green or yellowish whereas a healthy late instar larva is a vivid green. They slowly dehydrate and eventually die, at which point the larval body becomes rubbery and turns to black. We used next generation sequencing to identify the cause of mortality in the insects. Total RNA was extracted from 20 larvae in two cohorts, one with and one without apparent symptoms of disease, for deep sequencing on NovaSeq platform after eukaryote ribosomal RNA depletion. We identified several non-insect sequences belonging to viruses, bacteria, and fungi, but none of those showed significant abundance or enrichment in the infected dataset. The sequences related to a unicellular yeast, Saccharomyces cerevisiae, and they were among the highly expressed non-insect contigs; more than 5% of reads in both libraries mapped to the genome of this opportunistic microorganism.
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Measures of positive well-being are needed to support the shift away from a deficit-based approach to mental health. This study examined one measure, the Mental Health Continuum-Short Form (MHC-SF), as a measure of positive well-being used in school-based mental health monitoring efforts. This study used latent profile analysis (LPA) to explore the mental health classifications of 10,880 California high school students' responses to MHC-SF emotional, psychological, and social well-being items. Five latent mental wellness profiles emerged, including two ordered profiles (i.e., High Well-Being and Low Well-Being) and three profiles spanning the two ordered profiles. The High Well-Being profile had the most favorable psychological adjustment, and the three moderate well-being range profiles had differentiated functioning. Informing the utility of the MHC-SF, this study also compared the MHC-SF categorical diagnostic criteria with the LPA's empirical classification approach and found the two classification approaches to be congruent. The findings provide an impetus for educators to attend to students in moderate well-being ranges and emphasize promoting positive mental well-being as an essential component of school-based mental health services.
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Insect herbivores can regulate their food intake by mixing food sources with different nutrient content, but face the resulting challenge of ingesting various plant secondary metabolites. How insects deal with toxins in a complex nutrient environment is unclear. Here we investigated the influence of a classic plant secondary metabolite, allyl glucosinolate (sinigrin), and its hydrolyzed product allyl isothiocyanate (AITC), on the development of Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) when fed on diets with different protein-to-carbohydrate (p : c) ratios. We also examined the effects of these toxins on larval biochemistry, by chemically analyzing the frass produced by insects feeding on the different diets. As expected, AITC had a greater negative effect than sinigrin on H. armigera life-history traits. However, AITC at low concentration appeared to have a positive effect on some traits. Both sinigrin and AITC-induced detoxification activity in the gut, and the reaction was related to diet protein concentration. High-protein diets can provide the required free amino acid, especially cysteine, needed for the detoxification process. The nutrient content of the diet influences how plant secondary metabolites are handled, and the use of artificial diets in experiments investigating the metabolic fate of plant secondary compounds needs to be carefully evaluated.