Larval Survival Research Articles

Emergence of extensively drug-resistant hypervirulent Acinetobacter baumannii isolated from patients with bacteremia: bacterial phenotype and virulence analysis

ObjectivesIndividuals infected with extensively drug-resistant (XDR) Acinetobacter baumannii are difficult to cure and have a high mortality rate. In this study, we compared the genomic and phenotypic differences between XDR and non-multidrug-resistant (MDR) A. baumannii and further characterized hypervirulent XDR A. baumannii. MethodsA total of 1,403 Acinetobacter isolates were collected from patients with bacteremia between 1997 and 2015. Antimicrobial susceptibility test was performed to categorize isolates into non-MDR, MDR, and XDR groups. The presence of selected virulence-associated genes was determined by PCR. Bacterial phenotypes, including iron acquisition, biofilm formation, capsule production, and virulence to larvae and mice, were determined. ResultsMultilocus sequence types revealed the high prevalence of ST2 (81.6%) and ST129 (18.4%) among 49 XDR isolates and sequence types of 18 non-MDR isolates were more diverse. Virulence-associated phenotypic assays showed that XDR isolates had higher iron acquisition ability and capsule production and higher virulence to Galleria mellonella larvae. However, their biofilm formation ability was lower compared to that of non-MDR isolates. XDR isolates contained more virulence genes, tonB, hemO, abaI, and ptk, while non-MDR isolates contained more pld and ompA. Twenty-one XDR isolates caused <20% larvae survival rate after 7 days post-infection were defined as hypervirulent XDR isolates. Among them, isolates 1677 (ST129) and 929-1 (ST2) also caused the death of all infected mice within two days. ConclusionSome subpopulations of highly drug-resistant ST2 also exhibit high virulence. Therefore, it is of utmost importance to continue monitoring the spread of hypervirulent XDR A. baumannii isolates.

Common soluble carbohydrates affect the growth, survival, and fatty acid profile of black soldier fly larvae Hermetia illucens (Stratiomyidae).

The black soldier fly, Hermetia illucens (L. 1758), is an omnivorous saprophagous insect with a high potential for valorizing organic by-products rich in carbohydrates. Among carbohydrates, H. illucens relies on soluble sugars for the growth and storage lipid synthesis. This study aimed to assess the impact of common soluble sugars on the development, survival, and fatty acid composition of H. illucens. Monosaccharides and disaccharides were individually incorporated into a chicken feed diet. Cellulose was used as a control. Larvae fed glucose, fructose, sucrose, and maltose grew faster than control larvae. In contrast, lactose exhibited anti-nutritional effects on larvae, slowing down growth and reducing final individual weight. However, all soluble sugars produced larvae fatter than the control diet. Notably, the tested sugars shaped the fatty acid profile. Maltose and sucrose increased saturated fatty acid content compared to cellulose. Conversely, lactose increased the bioaccumulation of dietary unsaturated fatty acids. This study is the first to demonstrate the effect of soluble sugars on the fatty acid profile of H. illucens larvae. Our findings highlight that the tested carbohydrates have significant effects on black soldier fly fatty acid composition and can thus determine their final applications.

Incipient resistance of the African maize stemborer, Busseola fusca (Lepidoptera: Noctuidae) to Cry2Ab2 maize in South Africa.

Resistance of Busseola fusca (Lepidoptera: Noctuidae) to Cry1Ab was documented in 2006, 7 years after the first cultivation of MON 810 in South Africa. This was mitigated by introducing a second-generation Bacillus thuringiensis (Bt) maize (MON 89034), which contains the Cry1A.105 and Cry2Ab2 proteins. The first reports of B. fusca infestations of MON 89034 maize came in the KwaZulu-Natal province (2017-2018 cropping season), followed by reports in the Mpumalanga province (2022-2023 season). Here we report results of artificial diet- and plant-based laboratory assays to assess the susceptibility of B. fusca populations to the Bt proteins in MON 89034. Larvae were sampled from nine locations which included three where greater than expected injury due to B. fusca had been reported to MON 89034. Larval mortality in assays with diet-incorporated Cry2Ab2 protein was 100% for all except the three problem populations, showing that the Cry2Ab2 protein in MON 89034 is highly efficacious against B. fusca. In contrast, assays with Cry1A.105 did not cause significant mortality in any of the B. fusca populations including larvae from a susceptible reference. Larval survival on leaf tissue of MON 89034 maize after 7 days ranged between 75% and 91% for the three problematic B. fusca populations, compared to 0.4% to 9.6% for the five other populations. Therefore, MON 89034 is effectively a single-mode-of-action technology against B. fusca and carries an inherent high risk for the evolution of resistance. This study shows that the three B. fusca populations collected from locations with greater than expected damage to MON 89034 have resistance to the Cry2Ab2 protein and therefore to MON 89034 maize. This research emphasizes the importance of resistance monitoring and implementation of effective insect resistance management tactics. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Delineating early life stages of Belone belone: analysis of external morphology and postcranial skeletal development of the garfish

During fish larvae development functional, morphological, and physiological adaptations are key in larval survival strategies and can determine mortality bottlenecks. For many fish groups such as needlefish, which play crucial roles in marine food webs, studies on early life stages are almost lacking. Herein, the development, with focus on the postcranial skeleton, of the garfish Belone belone (Linnaeus, 1761) is described and a staging system is introduced. Ten larval and juvenile life stages are proposed in three main phases: yolk sac, larval, and juvenile development. During the yolk sac phase the garfish deplete their yolk reservoirs and finish the development of their unpaired fins. During the larval period the lower jaw elongates and the needlenose stage is reached. In the juvenile phase, the upper jaw elongates until both jaws are almost equally long. Since B. belone larvae develop much of their postcranial skeleton in the late embryonic and yolk sac phases they might not experience a severe bottleneck in this early stage such as many other marine fish species. Therefore, young garfish could be more resilient to environmental changes.

Postprandial Sleep in Short-Sleeping Mexican Cavefish.

Interactions between sleep and feeding behaviors are critical for adaptive fitness. Diverse species suppress sleep when food is scarce to increase the time spent foraging. Postprandial sleep, an increase in sleep time following a feeding event, has been documented in vertebrate and invertebrate animals. While interactions between sleep and feeding appear to be highly conserved, the evolution of postprandial sleep in response to changes in food availability remains poorly understood. Multiple populations of the Mexican cavefish, Astyanax mexicanus, have independently evolved sleep loss and increased food consumption compared to surface-dwelling fish of the same species, providing the opportunity to investigate the evolution of interactions between sleep and feeding. Here, we investigate the effects of feeding on sleep in larval and adult surface fish, and in two parallelly evolved cave populations of A. mexicanus. Larval surface and cave populations of A. mexicanus increase sleep immediately following a meal, providing the first evidence of postprandial sleep in a fish model. The amount of sleep was not correlated to meal size and occurred independently of feeding time. In contrast to larvae, postprandial sleep was not detected in adult surface or cavefish, which can survive for months without food. Together, these findings reveal that postprandial sleep is present in multiple short-sleeping populations of cavefish, suggesting sleep-feeding interactions are retained despite the evolution of sleep loss. These findings raise the possibility that postprandial sleep is critical for energy conservation and survival in larvae that are highly sensitive to food deprivation.

Immunomodulation and Protective Effects of Cordyceps militaris Extract Against Candida albicans Infection in Galleria mellonella Larvae

Cordyceps militaris-derived formulations are currently used for multiple purposes because of their medical properties, especially immune system modulation. This study analyzes the inhibitory effects of C. militaris aqueous extract on Candida albicans infections and the immune response in larvae of the greater wax moth Galleria mellonella (Lepidoptera: Pyralidae). Larvae exhibited melanization within 1 h of being infected with C. albicans inoculum at a concentration of 106 cells/larvae, and died within 24 h from a lethal dose. Aqueous extract of C. militaris proved to be nontoxic at concentrations of 0.25 and 0.125 mg/larvae, and had the greatest ability to prolong the survival of larvae infected with a sublethal dose of C. albicans at a concentration of 105 cells/larvae. Moreover, the number of hemocytes in the hemolymph of G. mellonella increased after infection with C. albicans and treatment with the aqueous extract of C. militaris at 1, 24, and 48 h by 1.21 × 107, 1.23 × 107, and 1.4 × 107 cells/100 µL, respectively. The highest number of hemocytes was recorded after treatment of infected G. mellonella with the extract for 48 h. Transcriptional upregulation of the immune system was observed in certain antimicrobial peptides (AMPs), showing that the relative expression of galiomicin, gallerimycin, and lysozyme genes were upregulated as early as 1 h after infection. Therefore, we conclude that C. militaris aqueous extract can modulate the immune system of G. mellonella and protect against infection from C. albicans.

Aerial litter mimicry: A novel form of floral deception mediated by a monoterpene synthase

Abstract Floral mimics deceive their pollinators by developing visual and olfactory resemblance to various models. We report a flower that exhibits phenotypes like aerial litter and deceives an aerial litter specialist beetle to achieve pollination. We assessed the floral phenology and the effective pollinators of an Australian understorey treelet, Meiogyne heteropetala (Annonaceae). The similarities of morphology, colour and odour between the flowers and co‐occurring aerial litter were investigated. The terpene synthase involved in floral scent emission was identified by expression patterns and product profile. The behavioural responses of the pollinator to various odours were assessed using bioassays. The erotylid beetle Loberus sharpi is the most likely effective pollinator because it was the only pollen‐laden visitor during the pistillate phase. Loberus sharpi was exclusively found in aerial litter and M. heteropetala flowers. The flowers offer an honest shelter reward. The beetle also oviposits there, but most larvae eventually perished as the petals dropped onto the forest floor. The morphology and spectral reflectance of the flowers overlap with aerial litter. The floral scent was dominated by monoterpenes, especially 1,8‐cineole. The cineole synthase MhCINS was the only highly expressed floral terpene synthase and possessed a highly similar product profile to the floral scent composition. The volatile composition of M. heteropetala flowers is distinct from other congeners and highly similar to aerial litter, indicating advergence to aerial litter. Visual and odour resemblance, coupled with low larval survivorship, provides evidence that the beetles were deceived into pollinating the flowers. Behavioural experiments showed that the pollinator was attracted to both aerial litter and M. heteropetala flowers. The beetles were also attracted to 1,8‐cineole and synthetic mixes of floral odour and MhCINS products. The beetles were unable to distinguish floral scent from MhCINS products nor from 1,8‐cineole, suggesting MhCINS alone sufficed to attract the pollinator olfactorily. The beetles, however, preferred aerial litter over flowers. The beetles likely categorised the flower as a general, but not the most preferred, brood substrate. Synthesis. This study reports the first case of floral mimicry of aerial litter and characterises the biochemical process responsible for olfactory mimicry.

Light spectrum effects on giant freshwater prawns, Macrobrachium rosenbergii: Larval development, survival and preferences

The objective of this study was to evaluate the influence of different light spectra on growth, development indices, survival and color preferences in Macrobrachium rosenbergii larvae. First (trial 1, 25 days), prawns (100 larvae/L) were randomly allocated to 30 cylindrical plastic containers (1 L). This trial was designed with five treatments (light spectra) and six replications: red light, blue light, green light and white light or absence of light (controls) in the 12:12 light:dark (LD) cycle. Next (trial 2), 30 groups of five larvae in two different development stages (VII and XI) were allocated to a system of compartments with different lights: white, red, blue or green. This system was connected by tubes to enable light spectra choices. Final weight, weight gain, consumption and metamorphosis significantly improved under the white light condition versus the other tested groups (p<0.05). Survival, the Larval Stage Index, the Larval Condition Index and final biomass clearly improved under the white light condition (p<0.05). Conversely, the red light and no light conditions obtained unsatisfactory results. White light was preferred in larvae stage VII (p<0.05), but this behavior changed to blue when prawns reached life stage XI (p<0.05). These findings suggest that white light may be the best choice to optimize larval growth and survival, while color preferences may vary with development stage.

Environmental Factors in Oryctes rhinoceros (Coleoptera: Scarabaeidae) Breeding

ABSTRACTThe Oryctes rhinoceros (Scarabaeidae: Coleoptera) is a common coleopteran insect in tropical and subtropical areas with many potential uses. Its larvae are commonly found in dead coconut trees and hay piles in the wild and are widely distributed in the northern hemisphere. This study investigates the environmental factors influencing the growth of Oryctes rhinoceros beetle larvae and provides valuable insights into their breeding conditions versus their potential applications. The research examined three key affecting factors of larval development over time, namely, moisture content, growth space and soil content. Results of a pretest run revealed that moisture content, but not the soil content, affected the larval survival greatly. A reasonable confinement on feed moisture (i.e., 30%–60%) was included in the later conducted three‐factor factorial experiment. At last, results of the factorial run suggested that: (1) for a consistent and massive larval breeding, environmental factors, setting moisture content at 60%, larval space at 100 cm3/larva and no soil addition, are deemed appropriate, (2) for nutritional purpose, setting moisture content at 60%, larval space at 300 cm3/larva and no soil addition are recommended, and (3) for soil pollution remediation, setting moisture content at 60%, larval space at 100 cm3/larva and a soil‐to‐feed (S/F) ratio of 2:1 is concluded. This study marks the first engineering breeding exploration of Oryctes rhinoceros larvae, offering practical recommendations for various research purposes and applications.

Assessment of Biology and Fertility Life Table of Coccinella septempunctata Linnaeus Predating on Mustard Aphid, Lipaphis erysimi Kaltenbach

Lipaphis erysimi (Kalt.), commonly known as the mustard aphid (Homoptera: Aphididae), is the most notorious, globally distributed, and obligatory ectoparasite of many field crop including rapeseed and mustard. An investigation was carried out to assess the biology and fertility life table of Coccinella septempunctata in Bio-control lab, Department of Entomology at CCS Haryana Agricultural University, Hisar following the standard protocol at the laboratory condition of temperature (T) 25±2°C, relative humidity (RH) 65±5% RH, and 16:8 light:dark (L:D). Biological studies revealed that Coccinella septempunctata (L.), predatoryfemale laying eggs either singly or in masses (546.90 eggs/female) were vibrant yellowand spindle shape with an incubation period of 3.50 days. Hatchability was 86.00±5.62 per cent. There were four grub instars followed by pre-pupal stage, mean grub duration of 1st, 2nd, 3rd and 4th instar was 1.68±0.47, 3.18±0.60, 3.08±0.65 and 5.02±0.73 days. Total grub duration extended for 12.97±0.61 days. Larval survival was 74.44 per cent, followed by a pre-pupal period of 1.05±0.18 days and pupal duration of 5.93±0.86 days. Total grubs and pupal period were computed to be 18.90 ± 1.16 days with adult emergence 77.22 per cent. Total developmental period, from egg to adult was 23.45±1.20 days. Adult became darker in colour and have seven spots, three on each wing and one in the middle, near the head and act as predator to control mustard aphid. Females of beetle survived longer than the males with ovipositional period of 23.10 days and preponderance of female has been noticed with female: male ratio of 1.62: 1 in the study.

Azoxystrobin Exposure Impacts on Development Status and Physiological Responses of Worker Bees (Apis mellifera L.) from Larval to Pupal Stages.

Honeybee larvae and pupae form the cornerstone of colony survival, development, and reproduction. Azoxystrobin is an effective strobilurin fungicide that is applied during the flowering stage for controlling plant pathogens. The contaminated nectar and pollen resulting from its application are collected by forager bees and impact the health of honeybee larvae and pupae. The current study evaluated the survival, development, and physiological effects of azoxystrobin exposure on the larvae and pupae of Apis mellifera worker bees. The field-recommended concentrations of azoxystrobin were found to suppress the survival indices and lifespan in the larval as well as pupal stages; moreover, the rates of the survival and pupation of larvae as well as the body weights of the pupae and newly-emerged adult bees were significantly reduced upon long-term exposure to azoxystrobin. In addition, azoxystrobin ingestion induced changes in the expression of genes critical for the development, immunity, and nutrient metabolism of larvae and pupae, although the expression profile of these genes differed between the larval and pupal stages. Results indicated the chronic toxicity of azoxystrobin on the growth and development of honeybee larvae and pupae, which would affect their sensitivity to pathogens and other external stresses during the development stage and the study will provide vital information regarding the pollination safety and rational use of pesticides.

Fitness Costs in Diamondback Moth Plutella xylostella (L.) (Lepidoptera: Plutellidae) Resistant to Lufenuron, A Chitin-Synthesis Inhibitor Insecticide

The diamondback moth (DBM), Plutella xylostella, is the main pest of Brassicas crops worldwide, and its recorded resistance to 101 active ingredients indicates it is difficult to control. The purpose of this study was to investigate the hypothesis that P. xylostella has fitness costs associated with its resistance to lufenuron, a chitin-synthesis inhibitor insecticide. Thus, concentration–mortality bioassays were performed for susceptible (REC-S), resistant (BZR-R) populations, their progenies F1 and F1′, and one established population without selection pressure (BZR-Rns) after four generations. A fertility life table was used to assess the biological performance of the REC-S and BZR-R. BZR-Rns of P. xylostella. The larval stage, longevity, and survival differed between populations. The reproductive rate (R0) was significantly lower in the F1 (♀R × ♂S) (28.19) and F1′ (♀S × ♂R) (34.06) progenies compared with their parents, but not with the relaxed BZR-Rns (39.39). The mean generation time (T), intrinsic rate of population growth (rm), and doubling time (DT) differed between REC-S and progenies, with fitness of 0.52 and 0.64 for F1 and F1′, respectively. Overall, the results suggest that the resistance of P. xylostella to lufenuron is stable and that low fitness costs appear to be associated with resistance to lufenuron, although heterozygotes showed lower fitness than their parents. Strategies such as preserving refuge areas, rotation of modes of action, etc., are essential for resistance management and prolonging the efficacy of control agents; this highlights the importance of integrated insecticide resistance management.

Bee microbiomes in a changing climate: Investigating the effects of temperature on solitary bee life history and health.

Climate change is rapidly warming thermal environments, an important abiotic stimulus governing interactions between microbial symbionts and their hosts. Increasing evidence suggests that solitary bees rely on pollen provision microbes for successful development. However, the effects of heat stress on provision microbiota and the resulting consequences for larval health and development remain to be examined. We performed an in vitro study to investigate the effects of the thermal environment on provision microbiome composition and measured fitness outcomes for Osmia lignaria larvae. While pollen sterilisation removed bacteria from microbe-rich provisions, larval survivorship did not significantly differ between bees reared on microbe-rich (unmanipulated) diets and provisions treated with ethylene oxide (EO) gas. In contrast to previous research in solitary bees, larvae reared on EO-treated provisions weighed more and had higher total fat content, with temperature moderating the degree of difference. As anticipated, we observed a negative relationship between the duration of larval development and temperature. Our results indicated that an intact provision microbiota may not always improve bee fitness and that bee-microbe interactions during larval development may contribute to the size-shrinking effect observed for cavity-nesting bees under warming conditions.

Genotypic Variation and Potential Mechanisms of Resistance against Multiple Insect Herbivores in Cranberries.

Plant genotypes often exhibit varying resistance levels to herbivores. However, the impact of this genotypic variation on resistance against multiple herbivores remains poorly understood, especially in crops undergoing recent process of domestication. To address this gap, we studied the magnitude and mechanism of resistance in 12 cranberry (Vaccinium macrocarpon) genotypes to three leaf-chewing herbivores - Sparganothis fruitworm (Sparganothis sulfureana), spotted fireworm (Choristoneura parallela), and spongy moth (Lymantria dispar) - along a domestication gradient (native 'wild' genotypes, 'early hybrid' genotypes, and 'modern hybrid' genotypes). Like cranberries, S. sulfureana and C. parallela are native to the United Sates, while L. dispar is an invasive pest. We measured the survival and growth of larvae on each genotype, as well as variation in plant performance (height and biomass) and leaf defensive chemical traits (C/N ratio, total phenolics, total proanthocyanidins, and flavonols levels) in these genotypes to elucidate potential resistance mechanisms. We found differences in C. parallela and L. dispar larval performance across genotypes, with larvae performing better on the modern hybrid genotypes, while S. sulfureana showed no differences. Morphological and chemical traits varied among genotypes, with total phenolics being the only trait correlated with C. parallela and L. dispar larval performance. Notably, the wild genotypes 'McFarlin' and 'Potter' had higher total phenolics and were more resistant to both herbivores than the modern hybrids 'Demoranville' and 'Mullica Queen.' This research contributes to a comprehensive understanding of the impact of crop domestication on multiple insect herbivores, offering insights for future breeding efforts to enhance host-plant resistance against agricultural pests.

A novel goldfish orthotopic xenograft model of hepatocellular carcinoma developed to evaluate antitumor drug efficacy

Tumor xenograft animal models play a crucial role in hepatocellular carcinoma (HCC) research. Mice xenograft models are time consuming, laborious and expensive while zebrafish tumor xenograft models are cost-effective and effortless. However, the development of orthotopic xenograft models for HCC in zebrafish embryos has been challenging due to the small size of zebrafish livers. In this study, we utilized 7-day-old goldfish embryos as hosts and successfully established an orthotopic xenograft model of HCC in goldfish livers. Through injecting fluorescence labeled HCC cells into the liver of goldfish, we could visualize the proliferation and migration of tumor cells in vivo. In addition, we found that the temperature of 36 °C was better for tumor cell survival in goldfish larvae compared to 28 °C, assessed by EdU and TUNEL assays. Moreover, macrophage infiltration in the goldfish liver could be evaluated by neutral red staining. Finally, we evaluated the efficacy of the targeted therapy drug Sorafenib and the traditional Chinese medicine, Huaier granules, alone or in combination in the goldfish HCC orthotopic xenograft model. We found that the combination therapy showed the best efficacy against HCC cells in terms of macrophage infiltration, polarization as well as tumor cells proliferation, metastasis and apoptosis. In conclusion, the proposed goldfish HCC orthotopic xenograft model opens new avenues for HCC related research, including evaluation of tumor progression, cell interactions in the immune microenvironment, drug efficacy, and screening of anti-tumor drugs.

Antimicrobial and antibiofilm activity of human recombinant H1 histones against bacterial infections.

Histones possess significant antimicrobial potential, yet their activity against biofilms remains underexplored. Moreover, concerns regarding adverse effects limit their clinical implementation. We investigated the antibacterial efficacy of human recombinant histone H1 subtypes against Pseudomonas aeruginosa PAO1, both planktonic and in biofilms. After the in vitro tests, toxicity and efficacy were assessed in a P. aeruginosa PAO1 infection model using Galleria mellonella larvae. Histones were also evaluated in combination with ciprofloxacin (Cpx) and gentamicin (Gm). Our results demonstrate antimicrobial activity of all three histones against P. aeruginosa PAO1, with H1.0 and H1.4 showing efficacy at lower concentrations. The bactericidal effect was associated with a mechanism of membrane disruption. In vitro studies using static and dynamic models showed that H1.4 had antibiofilm potential by reducing cell biomass. Neither H1.0 nor H1.4 showed toxicity in G. mellonella larvae, and both increased larvae survival when infected with P. aeruginosa PAO1. Although in vitro synergism was observed between ciprofloxacin and H1.0, no improvement over the antibiotic alone was noted in vivo. Differences in antibacterial and antibiofilm activity were attributed to sequence and structural variations among histone subtypes. Moreover, the efficacy of H1.0 and H1.4 was influenced by the presence and strength of the extracellular matrix. These findings suggest histones hold promise for combating acute and chronic infections caused by pathogens such as P. aeruginosa.IMPORTANCEThe constant increase of multidrug-resistant bacteria is a critical global concern. The inefficacy of current therapies to treat bacterial infections is attributed to multiple mechanisms of resistance, including the capacity to form biofilms. Therefore, the identification of novel and safe therapeutic strategies is imperative. This study confirms the antimicrobial potential of three histone H1 subtypes against both Gram-negative and Gram-positive bacteria. Furthermore, histones H1.0 and H1.4 demonstrated in vivo efficacy without associated toxicity in an acute infection model of Pseudomonas aeruginosa PAO1 in Galleria mellonella larvae. The bactericidal effect of these proteins also resulted in biomass reduction of P. aeruginosa PAO1 biofilms. Given the clinical significance of this opportunistic pathogen, our research provides a comprehensive initial evaluation of the efficacy, toxicity, and mechanism of action of a potential new therapeutic approach against acute and chronic bacterial infections.

Agroecological importance of smooth brome in managing wheat stem sawfly (Hymenoptera: Cephidae) via associated braconid parasitoids.

Wheat stem sawfly (WSS), Cephus cinctus Norton (Hymenoptera: Cephidae), is a major pest of cereal crops throughout the Northern Great Plains of North America. Native parasitoids, Bracon cephi (Gahan) and B. lissogaster Muesebeck (Hymenoptera: Braconidae), play a key role in suppressing WSS populations and limiting associated damage. Smooth brome grass (Bromus inermis Leyss.) serves as a potential trap reservoir for WSS when grown in areas surrounding wheat (Triticum aestivum L.) fields in Montana. Its unique biology allows it to support high WSS infestation while promoting significant larval mortality throughout the growing season. Late-season WSS survivors can then serve as hosts for WSS parasitoids. Our study investigated smooth brome as a host refuge for WSS parasitoids. We measured WSS larval infestation and survival rate inside smooth brome grown within WSS-inclusion cages, finding a maximum infestation of 66.5% and an end-of-year WSS survival of 5.7%. In addition, we collected stems from sites in central and north-central Montana to measure the WSS infestation and parasitoid prevalence in wheat and adjacent smooth brome. WSS infestation was high in both Big Sandy (64.5% smooth brome, 65.7% adjacent wheat) and Moccasin, MT (50.6%, 38.6%). Year-end WSS larval mortality was 43.6% greater in smooth brome compared to adjacent wheat at both field sites, but both hosted similar numbers of WSS parasitoids. This research underscores the importance of smooth brome in providing a sustainable host refuge for WSS parasitoids and highlights its significant role in supporting the economics of wheat cultivation.

Impact of Sublethal Insecticides Exposure on Vespa magnifica: Insights from Physiological and Transcriptomic Analyses

Insecticides are widely used to boost crop yields, but their effects on non-target insects like Vespa magnifica are still poorly understood. Despite its ecological and economic significance, Vespa magnifica has been largely neglected in risk assessments. This study employed physiological, biochemical, and transcriptomic analyses to investigate the impact of sublethal concentrations of thiamethoxam, avermectin, chlorfenapyr, and β-cypermethrin on Vespa magnifica. Although larval survival rates remained unchanged, both pupation and fledge rates were significantly reduced. Enzymatic assays indicated an upregulation of superoxide dismutase and catalase activity alongside a suppression of peroxidase under insecticide stress. Transcriptomic analysis revealed increased adenosine triphosphate-related processes and mitochondrial electron transport activity, suggesting elevated energy expenditure to counter insecticide exposure, potentially impairing essential functions like flight, hunting, and immune response. The enrichment of pathways such as glycolysis, hypoxia-inducible factor signaling, and cholinergic synaptic metabolism under insecticide stress highlights the complexity of the molecular response with notable effects on learning, memory, and detoxification processes. These findings underscore the broader ecological risks of insecticide exposure to non-target insects and highlight the need for further research into the long-term effects of newer insecticides along with the development of strategies to safeguard beneficial insect populations.

Dose-response effects of starch in sterilised and unsterilised chicken excreta on Musca domestica larval growth and bioconversion efficiency

Abstract Housefly (Musca domestica L.) larvae can convert animal manure into valuable protein and fat but little is known about their nutritional requirements. We assessed the effects of differential starch content in unsterilised (UE) and heat sterilised (SE) chicken excreta on larval performance and bioconversion. Gelatinized corn starch was added to excreta resulting in 11 diets with 0 to 50% starch of dry mass. Individual larval mass increased from (mean ± SD) 12 ± 0.2 (UE) and 13 ± 0.4 (SE) mg at 0% starch up to 18 ± 0.4 (UE) and 18 ± 0.5 (SE) mg at 15% starch and decreased to 5 ± 0.4 (UE and SE) mg in 50% starch. Higher starch concentrations resulted in non-normal distributions of individual larva mass. Larval wet yield showed a curvilinear relation with starch content, with maxima of 39 ± 2.3 g in UE at 10% starch, and 43 ± 2.8 g in SE at 15% starch. The decrease in yield after the maxima was faster in UE compared to SE. Larval survival was highest in 0% starch, 80 ± 8% (UE) and 72 ± 13 % (SE), linearly decreasing to 14 ± 7% (UE) and 18 ± 3% (SE) in 50% starch. Dry matter bioconversion increased from 4 ± 0.1% (UE) and 4 ± 0.3% (SE) in 0% starch to 6 ± 0.2 in UE with 10% starch and 7 ± 0.3 in SE with 15% starch, decreasing to close to 0 in 50% starch. Highest nitrogen bioconversion was 15 ± 0.5% in UE with 10% starch and 15 ± 0.5% in SE with 15% starch. Optimal starch inclusions increased nitrogen bioconversion with 40% (UE) and 100% (SE) compared to pure excreta. Finally, around 20 to 25% starch uric acid and ammonia contents, pH, and diet residue C/N decreased, indicating a tipping point. In conclusion, adding starch to chicken excreta can substantially increase larval yield and bioconversion while reducing ammonia content in the substrate residue.

Different responses of larval fatty acid profiles to cryopreservation in two commercially important bivalves.

Larval cryopreservation techniques have been established in Pacific oysters and Mediterranean mussels. Although initial cryopreservation protocols for both species differed slightly in Ficoll PM 70 (FIC) concentration, better post-thaw larval survivability was produced in mussels than oysters. Furthermore, the post-thaw survivability in the latter could be improved significantly by the addition of lipids and antioxidants to the cryoprotectant agent. These findings have generated a unique opportunity to investigate the cryo-functions of both endogenous and exogenous fatty acids (FAs) in bivalves as mammalian studies indicated that lipid compositions could contribute the interspecific difference in gamete and embryo cryopreservation. Our study showed that the higher survivability of post-thaw larvae in mussels (65% vs. 34% in oysters) could be attributed to their higher proportion of total polyunsaturated fatty acids (PUFAs), especially C22:6, and higher resistance of FA profiles to cryopreservation. In oysters, on the other hand, their FA profiles were very sensitive to cryopreservation, with saturated FAs and PUFAs being significantly increased (from 37 to 41%) and decreased (from 35% to ~ 32%), respectively. Although exogenous lipids could significantly improve the survivability of post-thaw oyster larvae from 34 to 51%, their supplementation did not alter the response pattern of endogenous FA profiles to cryopreservation.