Host Quality Research Articles

Multiple foundresses and multiple hosts: The influences of kinship and host quality on group reproduction in a quasi‐social parasitoid

Multiple foundresses and multiple hosts: The influences of kinship and host quality on group reproduction in a quasi‐social parasitoid

Effect of individual quick freezing treatment and cold storage on the host egg (Lepidoptera: Saturniidae) quality for the production of the parasitoid Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae)

BackgroundThe augmentative release of the parasitoid species Anastatus japonicus Ashmead (Hymenoptera: Eupelmidae) is essential for managing the recent invasion of litchi stink bugs (Tessaratoma papillosa (Drury)) (Hemiptera: Tessaratomidae) in Taiwan. The mass release program in the spring targets this univoltine pest’s reproduction cycle. Low-temperature storage for the host eggs and parasitoids is required to maximize the production for the annual release program. This study aimed to enhance the shelf life of Samia cynthia (Lepidoptera: Saturniidae) eggs using the combination of refrigeration and individual quick freezing (IQF) as a storage treatment. Storage of A. japonicus in the IQF-treated S. cynthia eggs was evaluated to determine the optimal production process during the short preparation window before the release.ResultsThe influences of cold storage and IQF treatment on the host eggs were evaluated for different storage durations. The host quality was determined according to the emergence rate and female ratio of A. japonicus. The study’s results demonstrated that the host quality of S. cynthia eggs did not change significantly compared to the control group after 28 d of refrigeration at 7 °C. IQF treatment extended S. cyathia’s shelf life to 5 months without significantly affecting the host quality. Applying IQF at different developmental stages of the host eggs affected the parasitism rates of A. japonicus. Significantly higher emergence rates of A. japonicus were recorded in the eggs treated during the initial development (D0 to D2). However, storing parasitoids in the IQF-treated eggs under the current storage condition for one month at 12 °C significantly impacted the parasitoid’s emergence rate.ConclusionsThe results of this study highlight the potential benefits of the individual quick freezing technique. This technique didn’t alter the egg quality of S. cynthia, a crucial factor for the mass production of A. japonicus. The IQF treatment extends the shelf life of the host eggs to 5 months when stored at − 20 °C, a significant improvement compared to the 4-week shelf life without IQF treatment. This technology offers a promising and efficient approach for the mass production of A. japonicus and supports field releases. The treatment allowed for the stockpiling of host eggs during the off-season, which can help expedite the mass production of A. japonicus to fit an eight-week production window.

Evaluation of biocompatibility and osseointegration of multi-component TiAl6V4 titanium alloy implants.

This study aimed to investigate the biocompatibility and osseointegration of novel titanium (Ti) implants with a perforated part with high surface roughness (Ra >4 μm) and a smooth solid part (test group), as compared to smooth solid Ti implants (control group; Ra < 0.8 μm). Test and control implants were implanted in rabbit femurs. After 4 and 15 weeks, host tissue reaction and quality of tissue formed were evaluated with histopathology, while micro-CT scans were used to quantitatively assess bone-implant contact (BIC), surrounding bone formation, and bone ingrowth. After 4 and 15 weeks, minimal host reaction was found in the test group. Histopathological analysis showed new bone formation around the implants in both the test and control groups after 4 weeks. Furthermore, additional bone growth was often observed within the holes of the test implants. After 15 weeks, the test implants showed high bone ingrowth and the presence of mature bone in direct contact with the implant surface, whereas, bone ingrowth was poorer for the control group with 30% of the control implants, showing larger gaps at the bone-implant interface. Quantitative micro-CT analysis revealed comparable BIC and bone formation in both groups at 4 weeks, but higher BIC and more bone formation in the test group than in the control group after 15 weeks. No significant differences were observed in any of the analyses. In conclusion, partially perforated, high-roughness Ti implants showed excellent osseointegration and minimal host reaction, indicating their potential for orthopedic applications in bone repair and regeneration.

Potential immunomodulatory effects of CAS+IMD monoclonal antibody cocktail in hospitalized patients with COVID-19

Passive administration of SARS-CoV-2 neutralizing monoclonal antibodies (mAbs), such as CAS+IMD (Casirivimab+Imdevimab) antibody cocktail demonstrated beneficial effects on clinical outcomes in hospitalized patients with COVID-19 who were seronegative at baseline and outpatients. However, little is known about their impact on the host immunophenotypes. We conducted an immunoprofiling study in 46 patients from a single site of a multi-site trial of CAS+IMD in hospitalized patients. We collected longitudinal samples during October 2020∼April 2021, prior to the emergence of the Delta and Omicron variants and the use of COVID-19 vaccines. All collected samples were analyzed without exclusion and post-hoc statistical analysis was performed. We examined the dynamic interplay of CAS+IMD with host immunity applying dimensional reduction approach on plasma proteomics and high dimensional flow cytometry data. Using an unbiased clustering method, we identified unique immunophenotypes associated with acute inflammation and disease resolution. Compared to placebo group, administration of CAS+IMD accelerated the transition from an acute inflammatory immunophenotype, to a less inflammatory or "resolving" immunophenotype, as characterized by reduced tissue injury, proinflammatory markers and restored lymphocyte/monocyte imbalance independent of baseline serostatus. Moreover, CAS+IMD did not impair the magnitude or the quality of host T cell immunity against SARS-CoV-2 spike protein. Our results identified immunophenotypic changes indicative of a possible SARS-CoV-2 neutralizing antibodies-induced anti-inflammatory effect, without an evident impairment of cellular antiviral immunity, suggesting that further studies of Mabs effects on SAS-CoV-2 or other viral mediated inflammation are warranted. Regeneron Pharmaceuticals Inc and federal funds from the Department of Health and Human Services; Administration for Strategic Preparedness and Response; Biomedical Advanced Research and Development Authority, under OT number: HHSO100201700020C.

Sex-specific manipulation of sexually cannibalistic mantid mating behavior by hairworms

Abstract Changes in the morphology, physiology, and behavior of parasitized organisms provide an ideal opportunity to examine the extended phenotype of parasites. Because the quality of the host directly affects the fitness of the parasite, parasites may increase their fitness by manipulating phenotypes of low-quality hosts. Males are usually preyed on by females in sexual cannibalism. Thus, the males of sexually cannibalistic species are unsafe and low-quality hosts for parasites, whereas females may be beneficial hosts because of the chance of nutrient intake from cannibalized males. Under passive modes of transmission, parasites cannot choose the host sex. Such parasites exploiting sexually cannibalistic organisms are subjected to contrasting fitness effects and may evolve to manipulate host mating behavior in a sex-specific manner: decreasing male mating to avoid cannibalism and promoting female mating to engage in cannibalism. We examined this hypothesis by a behavioral experiment using a mantid–hairworm system. Parasitized male mantids (Tenodera angustipennis) changed their behavior as expected, exhibiting increased escapes and decreased courtships and mountings, potentially avoiding encounters with the female. Interestingly, male attack behavior was promoted, possibly decreasing contact with the encountered female. However, contrary to our prediction, parasitized females also exhibited decreased propensities of mating, suggesting costs or little benefits of host mating for parasites in the female host. This study provides novel insights into the evolution of parasite strategies in response to sexual differences in host quality.

Effects of elevated CO2 and temperature on the performance of a diet specialized neotropical herbivore and its host plant

AbstractLittle is known about the potential responses of ecologically specialized tropical species to atmospheric change and global warming. In 2 years of greenhouse experiments simulating climate change impacts, we quantified the effects of mean ambient temperature, elevated temperature (Te), current ambient CO2 concentration ([CO2]a), and doubled CO2 concentration ([CO2]e) on biomass, growth rate, and foliar chemistry of the morning glory vine, Camonea umbellata. In addition, we measured the impacts of climate change simulations on the performance and survival of the tortoise beetle, Acromis sparsa, which feeds exclusively on C. umbellata. Full‐sib A. sparsa larval broods were divided into cohorts. Each cohort was placed in one of four temperature‐CO2 controlled chambers and fed leaves grown in their respective treatments. Vines growing in [CO2]e more than doubled their biomass and their leaves expanded faster. The [CO2]a and Te treatments interacted to yield the greatest foliar [C]. Vines in [CO2]e and Te had the greatest C:N ratios, the lowest availability of nitrogen, and highest larval mortality. Whereas pupae were smaller and suffered lower survival in Te, pupal mass and survival increased in both the [CO2]e and Te treatments. Overall, the simultaneous elevation of both [CO2] and temperature caused declines in host quality, larval survivorship, and pupal mortality that were not observed when only one climate factor was altered. Based on this first tropical experimental study, we predict that C. umbellata will benefit from elevation of temperature and atmospheric [CO2] by altering its foliar chemistry to the detriment of its diet‐specialized herbivore enemy.Abstract in Spanish is available with online material.

Biology of the parasitoid Melittobia sosui Dahms, 1984 (Hymenoptera: Eulophidae) with details on its ecology, development, and reproduction in Vietnam

Summary In this study, we determined the total developmental time of Melittobia sosui Dahms from the egg to the emergence of imagoes being 12.7–30 days for males and 14.7–34.6 days for macropterous females. Its developmental time depended on the laboratory temperature and humidity. Based on tests of the developmental time through 23 months from 2019 to 2021 and field-collected data, it is concluded that Melittobia sosui is active throughout year except for its pupal diapause lasting 2–3 weeks during the winter. The average life cycle was 23 ± 7.5 days. Males did not feed after emerging and lived from 6.5 to 8.2 days. Females feeding on host hemolymph had a life span from 29.2 to 42.2 days depending on the room temperature and humidity. The number of offspring produced depended on the host quality and varied from 65.6 to 145.4 individuals per foundress. Related to host weights, Melittobia sosui held an offspring clutch size of about 2.6 individuals per mg of Chalybion malignum (Kohl) and about 1.6 individuals per mg of Chalybion bengalense (Dahlbom) and of Sceliphron madraspatanum kohli Sickmann (three, Sphecidae). Regardless of the laboratory temperature and relative humidity, but depending on the host quality (different hosts), the sex ratio varied from 0.96 to 0.98, the average female-dimorphism ratio was 0.99 ± 0.01 and the mean developmental mortality rate of pupa was 0.92 ± 1.78%. Our findings provide a better understanding of the biology and ecology of Melittobia sosui and contribute to devising suitable control measures for the species.

Impact of Different Food Sources on the Developmental Biology and Host Preferences of the Red Flour Beetle Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

An experiment conducted at the seed center laboratory at Tamil Nadu Agricultural University during June 2022 evaluated the host preferences and developmental biology of the red flour beetle (Tribolium castaneum) across three food sources: broken rice with rice flour, broken wheat with wheat flour, and tapioca flour. Beetle development was observed in ventilated containers under controlled conditions (28-30°C, 65% relative humidity) with 25 beetles per container. Significant differences in beetle survival and development. Wheat flour was the most favourable host, with 304 live adults, followed by broken wheat (145 live adults. Rice flour supported 20 adults and 11 larvae, indicating moderate suitability. Whole rice grains and tapioca flour were the least effective, with only dead adults and few larvae. Despite host quality variations, the developmental stages (egg incubation: 4-7 days, larval: 65-70 days, pupal: 6-9 days) were consistent across food sources. Wheat flour is the most supportive environment for T. castaneum development.

Evolution of parasites in the Anthropocene: new pressures, new adaptive directions.

The Anthropocene is seeing the human footprint rapidly spreading to all of Earth's ecosystems. The fast-changing biotic and abiotic conditions experienced by all organisms are exerting new and strong selective pressures, and there is a growing list of examples of human-induced evolution in response to anthropogenic impacts. No organism is exempt from these novel selective pressures. Here, we synthesise current knowledge on human-induced evolution in eukaryotic parasites of animals, and present a multidisciplinary framework for its study and monitoring. Parasites generally have short generation times and huge fecundity, features that predispose them for rapid evolution. We begin by reviewing evidence that parasites often have substantial standing genetic variation, and examples of their rapid evolution both under conditions of livestock production and in serial passage experiments. We then present a two-step conceptual overview of the causal chain linking anthropogenic impacts to parasite evolution. First, we review the major anthropogenic factors impacting parasites, and identify the selective pressures they exert on parasites through increased mortality of either infective stages or adult parasites, or through changes in host density, quality or immunity. Second, we discuss what new phenotypic traits are likely to be favoured by the new selective pressures resulting from altered parasite mortality or host changes; we focus mostly on parasite virulence and basic life-history traits, as these most directly influence the transmission success of parasites and the pathology they induce. To illustrate the kinds of evolutionary changes in parasites anticipated in the Anthropocene, we present a few scenarios, either already documented or hypothetical but plausible, involving parasite taxa in livestock, aquaculture and natural systems. Finally, we offer several approaches for investigations and real-time monitoring of rapid, human-induced evolution in parasites, ranging from controlled experiments to the use of state-of-the-art genomic tools. The implications of fast-evolving parasites in the Anthropocene for disease emergence and the dynamics of infections in domestic animals and wildlife are concerning. Broader recognition that it is not only the conditions for parasite transmission that are changing, but the parasites themselves, is needed to meet better the challenges ahead.

Making a healthy choice: Tactical host selection behaviour of a parasitoid wasp

Abstract Host selection behaviour plays a pivotal role in determining the success of parasitoids, especially in environments where host quality varies. In heterogeneous environments, parasitoids frequently encounter hosts that are infected. We conducted experiments to ascertain whether the ecto‐parasitoid Bracon brevicornis can differentiate between healthy caterpillars and those infected with Bacillus thuringiensis (Bt) and examined the implications of this host selection behaviour. In an olfactometer choice assay, B. brevicornis avoided Bt‐infected Spodoptera litura hosts. In a no‐choice assay, the female parasitoid displayed a lower paralysis rate on infected hosts, indicating a strong selection behaviour. Furthermore, we explored the impact of infection duration by exposing female wasps to larvae infected for 24, 48 and 72 h with Bt. Both choice and no‐choice assays demonstrated that female B. brevicornis refrains from ovipositing on infected larvae, regardless of the infection duration. Direct exposure to Bt through consumption did not affect the fitness of the tested parasitoid wasp. However, post‐24‐h Bt infection, host larvae showed an increased total hemocyte density, particularly high phagocytic cell numbers, and enhanced melanization, rendering the host larva unsuitable for parasitoid development. Taken together, our study underscores that parasitoids exhibit robust host selection behaviour by actively avoiding infected hosts. This insight is valuable for devising new pest control strategies in agriculture that safeguard beneficial parasitoids.

Differential effects of plant-beneficial fungi on the attraction of the egg parasitoid Trissolcus basalisin response to Nezara viridula egg deposition.

There is increasing evidence that plant-associated microorganisms play important roles in defending plants against insect herbivores through both direct and indirect mechanisms. While previous research has shown that these microbes can modify the behaviour and performance of insect herbivores and their natural enemies, little is known about their effect on egg parasitoids which utilize oviposition-induced plant volatiles to locate their hosts. In this study, we investigated how root inoculation of sweet pepper (Capsicum annuum) with the plant-beneficial fungi Beauveria bassiana ARSEF 3097 or Trichoderma harzianum T22 influences the olfactory behaviour of the egg parasitoid Trissolcus basalis following egg deposition by its host Nezara viridula. Olfactometer assays showed that inoculation by T. harzianum significantly enhanced the attraction of the egg parasitoid, while B. bassiana had the opposite effect. However, no variation was observed in the chemical composition of plant volatiles. Additionally, fitness-related traits of the parasitoids (wasp body size) were not altered by any of the two fungi, suggesting that fungal inoculation did not indirectly affect host quality. Altogether, our results indicate that plant inoculation with T. harzianum T22 can be used to enhance attraction of egg parasitoids, which could be a promising strategy in manipulating early plant responses against pest species and improving sustainable crop protection. From a more fundamental point of view, our findings highlight the importance of taking into account the role of microorganisms when studying the intricate interactions between plants, herbivores and their associated egg parasitoids.

The Effect of Ficus semicordata Fig Quality on the Sex Ratio of Its Pollinating Wasp Ceratosolen gravelyi

The interaction between fig wasps and their host fig trees (Ficus spp.) is a striking example of an obligate pollination mutualism. Male and female fig wasps are confined within their natal patch instead of panmictic; under this circumstance, mating only occurs between individuals of the same patch. This is known as a local mate competition (LMC). It pays foundresses to invest mainly in daughters and to only produce enough sons to ensure that all female offspring can be fertilized, but in nature, pollinating fig wasps may face many problems with host quality, such as limitation of oviposition sites and the nutrition deficiency of the host fig. The sex ratio of wasps can determine the stability of fig–fig wasp mutualistic system and, thus, the stability of other species associated with it. In this study, we controlled the quality of host figs in three ways. The results showed that the host fig age can influence the sex ratio of pollinator offspring, while the foundress numbers and the presence of pollen have no significant effect on it. A compelling explanation for this result is that the sex-dependent mortality occurs. This is a novel finding of how host quality influences the interaction of fig and fig wasps, which can also help us understand the evolution and stability mechanism of this symbiotic system.

Study on the Influence of Host–Guest Interaction on Tourists’ Pro-Environment Behavior: Evidence from Taishan National Forest Park in China

This study explores the influence of host–guest interaction on tourists’ pro-environment behavior. On the one hand, the experience attribute of host–guest interaction’s influence on tourists’ experiential value is sorted out. On the other hand, the relationship attribute of host–guest interaction’s activation effect on tourists’ personal norms is identified. Based on social exchange theory and normative activation theory, a structural equation model was established to depict the transmission mechanism from host–guest interaction to tourists’ pro-environment behavior. The data were collected from tourists in Taishan National Forest Park (n = 499). The results indicated that host–guest interaction quality activated tourists’ personal norms through consequence awareness, thus promoting tourists’ pro-environment behavior. Meanwhile, the quality of host–guest interaction positively influenced tourists’ pro-environment behavior through emotional experience value. Host–guest interaction quantity promoted tourists’ pro-environment behavior by activating personal norms through responsibility ascription. In addition, although frequent host–guest interactions can enhance the social experience and functional experience value of tourists, the latter two cannot stimulate tourists’ pro-environmental behavior. This study provides practical implications for promoting the sustainable development of national forest parks.

Impact of susceptible wheat cultivars on epidemiological parameters involved in the introduction and spread of wheat dwarf disease

AbstractDefence mechanisms in plants have been naturally or artificially selected to cope with virus infection and/or insect colonization. This creates a range of host susceptibility to viruses and/or insects that can impact the epidemiology of insect‐borne viral diseases. Wheat dwarf disease (WDD), one of the most important viral diseases on small‐grain cereals, is caused by wheat dwarf virus (WDV), which is transmitted by the leafhopper Psammotettix alienus. In the current context of the unavailability of either WDV‐resistant/tolerant wheat cultivars or effective methods to control WDD in French cereal fields, the accurate characterization of WDV‐susceptible genotypes must be considered to improve management strategies against this viral disease. In this study, the impact of 12 wheat cultivars on epidemiological parameters related to the introduction (host selection and virus infection) and spread (insect performance and virus transmission) of WDD was evaluated. Results showed no differences between the tested cultivars for host selection made by P. alienus, whereas four tested cultivars (Complice, Filon, Hyking and Nemo) reduced survival and/or fecundity of the leafhopper. Characterization of virus–host interactions highlights the lower host and source quality of cv. Filon for WDV. Finally, multivariate analyses allowed the identification of cvs Filon, Boregar, Solindo CS, Complice and Hyking as less suitable hosts for WDV and/or P. alienus, suggesting that these cultivars could present interesting genetic resource(s) that should be considered for future breeding programmes against WDD.

Alcon Blues: recent shifts in limiting habitat factors challenge the persistence of an endangered butterfly

Insect habitat specialists have declined more than generalists over the last decades. Understanding how habitat requirements and increased climate variability interact to explain persistence of populations is needed to enable effective conservation measures. Habitat specialists with a complex life cycle, such as myrmecophilous butterflies, are likely to be most vulnerable. Here, we explored to what extent the habitat factors explaining population persistence of the Alcon blue (Phengaris alcon), changed over a 25-year period in the Netherlands, contrasting the recent years 2018–2022 with extreme droughts with the preceding period 1998–2017 characterized by occasional climatic extremes. Population persistence of P. alcon over 1998–2017 as explained by historical habitat conditions was significantly higher in large heathland areas with large patches of its host plant Gentiana pneumonanthe. On the basis of current conditions, population persistence until 2017 was best explained by a combination of host plant area and quality. In contrast, persistence over the recent drought years was most closely associated with increasing occupancy of the optimal host ant Myrmica ruginodis and lower occupancy of competitive and predatory Lasius ants.Implications for insect conservation We conclude that critical habitat conditions change under increasing climatic extremes and that the availability of sufficient optimal host ants has become more critical than that of host plants. The results emphasise that both large-scale hydrological restoration and small-scale management for heterogeneity are necessary to preserve P. alcon and its habitat in the Netherlands. This is also likely to apply to other habitat specialists with complex life cycles from threatened habitats.

Begomovirus Transmission to Tomato Plants Is Not Hampered by Plant Defenses Induced by Dicyphus hesperus Knight.

Plants can respond to insect infestation and virus infection by inducing plant defenses, generally mediated by phytohormones. Moreover, plant defenses alter host quality for insect vectors with consequences for the spread of viruses. In agricultural settings, other organisms commonly interact with plants, thereby inducing plant defenses that could affect plant-virus-vector interactions. For example, plant defenses induced by omnivorous insects can modulate insect behavior. This study focused on tomato yellow leaf curl virus (TYLCV), a plant virus of the family Geminiviridae and genus Begomovirus. It is transmitted in a persistent circulative manner by the whitefly Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), posing a global threat to tomato production. Mirids (Hemiptera: Miridae) are effective biological control agents of B. tabaci, but there is a possibility that their omnivorous nature could also interfere with the process of virus transmission. To test this hypothesis, this study first addressed to what extent the mirid bug Dicyphus hesperus Knight induces plant defenses in tomato. Subsequently, the impact of this plant-omnivore interaction on the transmission of TYLCV was evaluated. Controlled cage experiments were performed in a greenhouse setting to evaluate the impact of mirids on virus transmission and vector acquisition by B. tabaci. While we observed a reduced number of whiteflies settling on plants exposed to D. hesperus, the plant defenses induced by the mirid bug did not affect TYLCV transmission and accumulation. Additionally, whiteflies were able to acquire comparable amounts of TYLCV on mirid-exposed plants and control plants. Overall, the induction of plant defenses by D. hesperus did not influence TYLCV transmission by whiteflies on tomato.

Abstract 4954: Improving microbial detection in cancer tissue samples with computational host depletion using the pangenome

Abstract Sensitive removal of host genetic information (i.e., host depletion) is a key first step towards accurate classification of potential microbial DNA sequences in low-biomass samples, such as human tumors. Inadequate filtration of human reads prior to microbial classification can cause false positives, biasing biological conclusions. Previous computational host depletion pipelines predominantly employed the human reference genome GRCh38 (hg38), which lacks genetic diversity of the human population and excludes substantial portions of the Y-chromosome. To address these deficiencies, we constructed a pipeline to maximally remove human reads that incorporates hg38, the first complete genome build T2T-CHM13v2.0 (T2T), and the 47 diploid genomes from the Human Pangenome Reference Consortium (HPRC) [1]. Reads passing maximal host depletion and quality control are considered sufficiently cleaned for downstream microbial analyses. We first evaluated the specificity of our pipeline by simulating Illumina whole genome sequencing (WGS) data from 10 heldout HPRC humans, whose genomes were excluded from the host depletion pipeline. We found significant improvement in the median number of human reads remaining across successive host depletion methods (hg38, 0.05369%; hg38+T2T, 0.00535%; hg38+T2T+HPRC, 0.00093%). For sensitivity, we applied our pipeline to simulated data from 962 microbes in the FDA-ARGOS dataset and found minimal removal of true microbial reads (median 99.9390% reads retained). As a real world example, we evaluated our pipeline on 583 metastatic colorectal cancer tissue (WGS) samples from the Hartwig Medical Foundation (HMF) database (median 106X coverage)[2] and found successive decreases in median number of reads retained (hg38, 185,135; hg38+T2T, 92,951; hg38+T2T+HPRC, 10,314). Using Woltka for taxonomic classification against database RefSeq210, we assessed biological sex similarity across the HMF samples using Robust Aitchison PCA (RPCA). Notably, microbial data following hg38-only host depletion showed significant microbial differences between male and female-labeled samples (p=0.00001), which was biologically unexpected. However, our updated pipeline (hg38+T2T+HPRC) removed the false sex-based separation in the microbial data (p=0.1837). Thus, utilization of diverse sets of complete human genomes for computational host depletion can mitigate artifactual bias, enabling more sensitive and specific host-microbe conclusions in cancer research. [1] Liao, et al. Nature 617, 312-324 (2023). [2] Priestley, et al. Nature 575, 210-216 (2019). Citation Format: Caitlin Guccione, Lucas Patel, Daniel McDonald, Cameron Martino, Antonio González, Gregory D. Sepich-Poore, Rob Knight, Kit Curtius. Improving microbial detection in cancer tissue samples with computational host depletion using the pangenome [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4954.

Maize terpene synthase 1 impacts insect behavior via the production of monoterpene volatiles β-myrcene and linalool

Plant-derived volatiles are important mediators of plant-insect interactions as they can provide cues for host location and quality, or act as direct or indirect defense molecules. The volatiles produced by Zea mays (maize) include a range of terpenes, likely produced by several of the terpene synthases (TPS) present in maize. Determining the roles of specific terpene volatiles and individual TPSs in maize-insect interactions is challenging due to the promiscuous nature of TPSs in vitro and their potential for functional redundancy. In this study, we used metabolite GWAS of a sweetcorn diversity panel infested with Spodoptera frugiperda (fall armyworm) to identify genetic correlations between TPSs and individual volatiles. This analysis revealed a correlation between maize terpene synthase 1 (ZmTPS1) and emission of the monoterpene volatiles linalool and β-myrcene. Electroantennogram assays showed gravid S. frugiperda could detect both linalool and β-myrcene. Quantification of headspace volatiles in a maize tps1 loss-of-function mutant confirmed that ZmTPS1 is an important contributor to linalool and β-myrcene emission in maize. Furthermore, pairwise choice assays between tps1 mutant and wild-type plants showed that ZmTPS1, and by extension its volatile products, aid host location in the chewing insect S. frugiperda, yet repel the sap-sucking pest, Rhopalosiphum maidis (corn leaf aphid). On the other hand, ZmTPS1 had no impact on indirect defense via the recruitment of the parasitoid Cotesia marginiventris. ZmTPS1 is therefore an important mediator of the interactions between maize and its insect pests.

Rising from the shadows: Selective foraging in model shoot parasitic plants.

Despite being sessile, plants nonetheless forage for resources by modulating their growth. Adaptative foraging in response to changes in resource availability and presence of neighbours has strong implications for performance and fitness. It is an even more pressing issue for parasitic plants, which draw resources directly from other plants. Indeed, parasitic plants were demonstrated over the years to direct their growth towards preferred hosts and invest resources in parasitism relative to host quality. In contrast to root parasites that rely mostly on chemical cues, some shoot parasites seem to profit from the ability to integrate different types of abiotic and biotic cues. While significant progress in this field has been made recently, there are still many open questions regarding the molecular perception and the integration of diverse signalling pathways under different ecological contexts. Addressing how different cues are integrated in parasitic plants will be important when unravelling variations in plant interaction pathways, and essential to predict the spread of parasites in natural and agricultural environments. In this review, we discuss this with a focus on Cuscuta species as an emerging parasitic model,and provide research perspectives based on the recent advances in the topic and plant-plant interactions in general.

Suitability of the shrub-steppe habitat of Eastern Washington for Halyomorpha halys (Hemiptera: Pentatomidae).

The invasive brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), has spread throughout most of Washington (WA) State since its detection in 2012. While it has emerged as a major agricultural and nuisance pest in the Pacific Northwest (PNW) west of the Cascade Mountains, pest pressure in the major tree fruit-growing areas in semi-arid northern and central WA State remains low. The reasons for this are unclear, although both biotic and abiotic conditions may be contributing factors. We evaluated the suitability of a common shrub-steppe/riparian corridor plant assemblage for supporting H. halys development from egg to adult in summer and fall through controlled feeding studies. Nymphs successfully completed development on this diet of PNW native plants, though it generally resulted in lower survivorship and adult weight and longer developmental times than a modified colony diet or a diet of known hosts from the eastern United States. These developmental data were used to parameterize stage-structured matrix models to predict the impact of diet and extreme heat events on H. halys population growth. The predicted net reproductive rate (R0) of H. halys was consistently and substantially reduced by a diet of PNW native plants, and heat shock imposed further severe reductions in R0. Our results suggest that the combined population effects of suboptimal plant host quality and regional heat waves may explain the lack of landscape-level H. halys pest pressure in semi-arid regions of the PNW.