Search Results (1,150)

Insect-mediated bioconversion is a promising strategy for livestock manure recycling, but its effects on antibiotic resistance genes (ARGs) in residual substrates remain insufficiently understood, especially under polystyrene particle exposure. In this study, swine manure was treated with Sarcophaga peregrina larvae under four concentrations of 100-nm polystyrene particles (PS particles: 0, 0.001, 0.01 and 0.1 mg/kg), and ARG profiles in air-dried residual manure were characterized. Larval treatment reduced manure mass by approximately 40% within 4 days, and reduction rates did not differ significantly among PS particle concentrations. However, larval treatment increased RPKM-normalized total ARG abundance relative to the corresponding controls, whereas the residue mass-adjusted relative ARG index remained below 1.0 in all larval treatment groups after incorporating residue mass. ARG richness and Shannon diversity were not significantly reduced. ARO-level turnover analysis showed both newly detected and no longer detected ARG types after larval treatment. PCoA and PERMANOVA indicated treatment-associated differences in resistome structure, with PERMDISP suggesting that dispersion also contributed. At class and mechanism levels, multidrug resistance and antibiotic efflux were dominant. These results indicate that S. peregrina larvae efficiently reduce manure mass, but their effects on ARGs are better described as residual resistome restructuring rather than ARG removal. Full article

The brown dog tick, Rhipicephalus sanguineus sensu lato (s.l.), is of medical and veterinary relevance and is primarily controlled with acaricides. Because acaricide resistance in this tick is a growing concern, evaluating effective acaricides is particularly important in Baja California, where tick-borne pathogens associated with R. sanguineus s.l. are endemic. This study aimed to estimate a candidate discriminating concentration (DC) for fipronil in R. sanguineus s.l. from the city of Mexicali and to assess fipronil susceptibility in three tick populations. Engorged female ticks were collected from naturally infested dogs in Valle de Puebla, Solidaridad Social, and El Encanto. After hatching, larvae were exposed to seven concentrations of a commercial fipronil formulation (0.0016%, 0.0032%, 0.0047%, 0.0062%, 0.0093%, 0.0125%, and 0.025%) using the larval packet test. Mortality at 24 h was analyzed by probit regression to estimate the median lethal concentration (LC50) and the lethal concentration for 99% mortality (LC99). The estimated LC50 and LC99 were 0.0031% (95% CI: 0.0022–0.0042%) and 0.025% (95% CI: 0.0178–0.0331%). A candidate DC of 0.05% was estimated for the Valle de Puebla population. Application of this concentration to the other populations showed 100% mortality when exposed to both 0.025% and 0.05% fipronil, indicating similar susceptibility across all evaluated populations. These findings provide preliminary susceptibility data for future monitoring of fipronil susceptibility in R. sanguineus s.l. populations from Mexicali and suggest that this acaricide may remain a useful option for urban tick control where local populations are susceptible. Full article

Pesticides represent a significant threat to aquatic ecosystems due to their persistence and widespread use in agricultural areas, altering environments and exerting adverse effects on non-target organisms. Tebuthiuron is a phenylurea herbicide extensively used as an agrochemical to control pests and weeds in various crops, which often leads to contamination of aquatic environments. Despite its high water solubility and relatively long half-life in soil, studies on Tebuthiuron toxicity in fishes at environmental concentrations are limited. This study aimed to unravel the toxicity mechanisms of Tebuthiuron using the zebrafish model. Zebrafish embryos were exposed to Tebuthiuron (one concentration of either 0.1, 10, 1000 and 5000 µg/L) for 5 days and assessed for hatchability, heart rate, locomotor activity, oxygen reactive species, apoptosis and gene expression. There was no change in frequency of hatch, heart rate, or apoptosis. However, behavioral changes were noted, with hyperactivity in zebrafish larvae during the first light (at 10 µg/L), second light (at 10 and 1000 µg/L) and third dark (10 µg/L) periods of the Visual Motor Response assay. Biochemically, a significant depletion of basal ROS levels was observed at 1000 µg/L. At the molecular level, downregulation of oxidative stress-related genes (cat, sod1, and sod2) in larval fish was noted with exposure to 10 and 5000 µg/L Tebuthiuron, suggesting a depletion of antioxidant enzymes. In addition, some neurotoxicity-related genes were downregulated, such as acetylcholinesterase (ache), while some genes were upregulated, like microtubule-associated protein tau b (maptb) and synapsin 2 alpha (syn2a), with 5000 µg/L Tebuthiuron exposure. In conclusion, Tebuthiuron induces sublethal toxicity characterized by irregular, concentration-specific disruptions to photomotor behavior, basal ROS levels, and transcriptional markers of oxidative stress and synaptic function, even in the absence of acute morphological defects. Future research should prioritize functional assays targeting mitochondrial bioenergetics and antioxidant enzyme activities, alongside evaluations of later developmental stages, to fully elucidate the long-term ecological risks of phenylurea herbicides to non-target aquatic species. Full article

The melon fly, Zeugodacus cucurbitae, and the oriental fruit fly, Bactrocera dorsalis, are economically important tephritid pests whose sympatric distribution and overlapping host ranges precipitate intense interspecific competitive interactions. To explore the interspecific competition during larval development between these two species, we conducted a comparative study under controlled laboratory conditions. Larvae were evaluated on five host fruits—pumpkin (Cucurbita moschata), cucumber (Cucumis sativus), winter melon (Benincasa hispida), bitter gourd (Momordica charantia), and guava (Psidium guajava)—across six larval density gradients (4.0, 1.33, 0.8, 0.57, 0.44, and 0.36 larvae g⁻¹ of host tissue). In mixed-species treatments, Z. cucurbitae exhibited significantly higher survival rates and greater adult dry weights than B. dorsalis on all cucurbit hosts except guava, indicating a consistent competitive advantage. Under high-density conditions, mixed-species treatments displayed stronger competitive effects than single-species treatments. Survival rate and adult dry weight of both species were significantly affected by the interactive effects of host plant species and larval density, with these factors jointly determining competitive outcomes. These findings improve our understanding of interspecific competition in tephritid fruit flies and provide a scientific basis for developing more effective management strategies for these economically important pests. Full article

The increasing demand for sustainable protein sources has stimulated interest in edible insects such as Tenebrio molitor (yellow mealworm) larvae. While probiotics supplementation has been explored to improve insect growth performance, its impact on protein quality and downstream processing remains poorly understood. This study investigated the combined effects of probiotic-enriched diet supplementation during larval rearing and post-harvest ultrasound-assisted extraction (UST) on the protein and lipid fractions of yellow mealworm larvae. Three probiotic strains, namely, Pediococcus pentosaceus (PP), Bacillus velezensis (BV), and Bacillus coagulans (BC), were incorporated into larval diets and compared with a standard diet (without probiotics). Protein extraction was performed by both alkaline solubilization–isoelectric precipitation, which served as a control, and ultrasound application for 5, 15, and 25 min. The results from the trial found effects of both probiotics and UST, as well as their interaction, on the protein yield, although an improvement in yield was not obtained with increased sonication, and the BV group produced the highest yield among the probiotic treatment groups. In addition to this, the study did not find any effects associated with ultrasound pretreatment or probiotics on proximate composition and color, except fat % and increased lipid co-extraction, especially at longer durations. Probiotics, on the other hand, showed an influence on the fatty and amino acid profile, while they interacted with UST to affect the extracts’ content. This study did not find any effects on particle size, but the zeta potential was affected by probiotic diet enrichment. Similarly, the free SH content was influenced by sonication, while both probiotics and UST played a role in hydrophobicity. Regarding the solubility, it was found to be pH-dependent and ranged from 0 to ≈90%. Importantly, this study found that probiotics did not have any effect on protein solubility; however, UST had an effect at pH 2 and 7 but not at pH 11. In terms of hydrophobicity, both factors and their interactions were found to have an effect. Moreover, this study could not determine any effects on the inherent fluorescence absorbance of protein molecules. Apart from this, FTIR analysis revealed β-sheet-dominated secondary structures (≈41–47%), with treatment-dependent shifts in α-helix and β-turn contributions. The heat enthalpies associated with denaturation and melting temperature were influenced by sonication, where probiotics could not confer an effect. Overall, this study might demonstrate the strain-specific improvement in protein yield and modulation of the physicochemical functionality, as well as the nutritive value of the protein. Both biological factors and ultrasound-assisted extraction processes can act together to tailor the physicochemical and functional properties of biofractions, but more studies are needed for process optimization. Full article

Chilo sacchariphagus is a destructive sugarcane borer worldwide, and frequent extreme high temperatures disrupt its field populations. Clarifying larval thermal response mechanisms provides theoretical support for pest risk prediction under climate warming. Previous work has illustrated moderate heat induces canonical HSP activation, but the molecular responses of this pest to 41 °C extreme heat remain unclear. As such, we conducted non-reference transcriptome sequencing and 11 physio-biochemical assays on fifth-instar larvae exposed to 41 °C for 12 h (26 °C as control) to characterize its thermal regulatory network. De novo assembly yielded a comprehensive transcriptome resource, and analysis of differentially expressed genes revealed enrichment in energy metabolism, ER protein processing, MAPK signaling and autophagy pathways. Core HSP70/40 transcripts were significantly down-regulated while HSP80 showed stable transcription, suggesting that 41 °C may exceed the heat-shock protective threshold and potentially trigger heat damage. qRT-PCR validation of seven core stress genes confirmed the RNA-seq trends. Catalase (CAT) activity increased significantly; however, none of the annotated catalase genes showed transcriptional changes, whereas elevated CarE and AchE activities also lacked corresponding transcriptional shifts, implying post-translational or alternative regulatory mechanisms. Our data showed coordinated transcriptional and physiological changes under extreme heat. These findings provide a basis for further investigation into how C. sacchariphagus may respond to extreme heat under climate warming scenarios. Full article

Insects lack adaptive immunity and rely exclusively on innate immune system for pathogen defense. However, the specific role of BmToll9-2, a key Toll receptor in the silkworm (Bombyx mori), in mediating immune responses, particularly against bacterial challenges in the larval fat body, remains incompletely understood. To address this gap, this study employed a combination of molecular approaches, including RNA interference (RNAi) targeting BmToll9-2, bacterial challenges with heat-inactivated Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), and quantitative real-time PCR (qPCR) to assess the transcriptional changes of BmToll9-2 and immune-related genes in the fat body, a key immune tissue. Quantitative analysis showed that after BmToll9-2 RNAi, bacterial challenges significantly upregulated BmToll9-2 expression in the fat body at 12 h post-challenge, whereas BmToll9-2 silencing alone notably downregulated most downstream signaling genes of the Toll pathway by 53.07–83.14%, as well as 11 immune effector genes, including antimicrobial peptide genes, by 64.48–93.40%. Importantly, feeding bacteria post-RNAi reversed these downregulations: E. coli induced a stronger upregulation of both signaling and effector genes compared to S. aureus. This study provides transcriptional evidence that BmToll9-2 may act as a positive regulator of the Toll pathway signaling and antimicrobial peptides in silkworm larval fat body, facilitating robust and rapid immune signaling. This study deepens our understanding of Lepidopteran innate immunity by elucidating key molecular mechanisms, thereby providing a solid foundation for refining RNAi-based pest control strategies. Full article

The Sterile Insect Technique (SIT) is a species-specific and effective insect population control technique that has the potential to be an alternative to chemical insecticides. The use of the SIT for mosquito population control is currently in development. An obstacle to the success of this technique is the decline in fitness of radiation-sterilized males. We propose that radiation exposure and specific larval diets change the bacterial microbiota of sterile adult male Aedes aegypti. To test this, we reared larvae on either a cat or fish food diet, irradiated the pupae, and isolated DNA from adult male abdomens three days post-irradiation. We then used 16s rRNA sequencing technology to characterize the bacterial microbiota. Our findings show for the first time in mosquitoes that larval diets change the effect of ionizing radiation on the adult bacterial microbiota. Full article

The fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae), is a devastating pest of maize, and host plant resistance offers a sustainable alternative to chemical control. This study evaluated the resistance of the maize germplasm CH1 against FAW through life table parameters, feeding and oviposition preferences and greenhouse experiment. Results showed that FAW larvae reared on CH1 exhibited significantly prolonged larval development (21.61 d vs. 12.49 d), reduced survival (65.00% vs. 94.00%), and lower fecundity (689.00 vs. 1369.93 eggs per female) compared to those on the susceptible control Huang C. Population parameters, including the intrinsic rate of increase (r) and net reproductive rate (R₀), were significantly lower on CH1. Behavioral assays revealed strong feeding and oviposition preferences for Huang C over CH1. Greenhouse experiment confirmed that CH1 plants sustained only minor damage (Davis scale grade 2, resistant), whereas Huang C plants were severely damaged (grade 7, susceptible). These findings demonstrate that CH1 possesses multi-dimensional resistance against FAW, providing a promising genetic resource for breeding FAW-resistant maize varieties and supporting sustainable pest management strategies. Full article

Estuaries support distinct spawning and nursery habitats for migratory fishes, yet the differential environmental response patterns between these two critical early life habitats remain poorly understood from a spatial non-stationarity perspective. Based on six ichthyoplankton surveys conducted during peak and late spawning seasons from 2018 to 2020 in the Yangtze Estuary, this study applied geographically weighted regression (GWR) models to quantify the spatially varying effects of sea surface temperature, sea surface salinity, chlorophyll-a, water depth and distance to coast on the distributions of Coilia mystus eggs and larvae. The results reveal clear divergence in both spatial pattern and environmental drivers between spawning and nursery habitats. Spawning grounds were persistently concentrated in the middle reaches of the South Branch, and shifted approximately 10 km upstream during the spring saltwater intrusion event in 2020. Nursery grounds, by contrast, formed a stable dual-core structure, with the northern core at the North Branch mouth consistently supporting higher larval densities than the southern core in the North and South Passages. Salinity was the primary limiting factor for spawning in spring, while temperature dominated in summer, and chlorophyll-a was never retained in optimal egg models. For larvae, chlorophyll-a emerged as a consistent key driver alongside salinity and temperature, and local regression coefficients spanned a wider range than those for eggs, indicating greater spatial heterogeneity in larval distribution–environment relationships. This study provides the first comparative analysis of spatially non-stationary environmental controls on spawning versus nursery habitats of C. mystus, and offers empirical support for stage-specific habitat conservation and fisheries management in the Yangtze Estuary. Full article

Sec61β encodes one of the subunits of the Sec61 translocon, which is essential for translocation of the nascent polypeptides to the endoplasmic reticulum (ER). Knockdown of Sec61β in the testis leads to male sterility in Drosophila melanogaster. Although Sec61β is expressed in both testes and ovaries, its role in female reproduction remains unclear. In this study, we found that knockdown of Sec61β in either germ cells or somatic cells of ovaries causes complete female sterility, with a small size of ovaries from larval to adult stages, significant reduction in germ cell numbers beginning in the late third-instar larval stage and a complete absence of germ cells in pupal and adult ovaries. Overexpression of Sec61β efficiently rescues these defects. Furthermore, we observed that Sec61β knockdown in the germline triggers the unfolded-protein response (UPR), which not only non-autonomously activates JAK/STAT signaling in adjacent somatic cells to inhibit Bam expression but also autonomously impedes the G1/S phase progression of germ cells. These effects collectively impact cell proliferation and differentiation. Our results suggest that Sec61β is essential for germ cell maintenance via UPR-mediated cell-autonomous proliferation control and non-autonomous JAK/STAT signaling in Drosophila ovaries. Full article

The larvicidal and biochemical effects of Ipomoea carnea Jacq. (Convolvulaceae) methanol leaf extract against the fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae) were determined under standard laboratory conditions. The second and fourth instar larvae of S. frugiperda were fed on castor bean leaves (Ricinus communis) treated with different concentrations (1–5%) of I. carnea methanolic leaf extract. The mortality percentage significantly increased in correlation with both concentration and exposure time compared to control. Second instar larva of S. frugiperda was more susceptible to this extract than the fourth instar, with LC₅₀ values of 0.968% and 1.052%, respectively. Castor bean leaves treated with 5% extract and fed to second and fourth larval instar caused 96.3 and 92.9% larval mortality, respectively. Results from the biochemical analysis of larvae treated with I. carnea methanolic leaf extract revealed a significant reduction in total content of carbohydrate, protein and lipid compared to control. I. carnea methanolic leaf extract induced significant inhibition of acetylcholinesterase, α-esterase and β-esterase activities, alongside increase in peroxidase activity compared to the control groups. The current results are consistent with neurophysiological disruption and activation of oxidative stress in the treated S. frugiperda larvae. Therefore, we recommend I. carnea methanolic leaf extract for controlling S. frugiperda. Further field investigation into the efficacy of I. carnea methanolic leaf extract against S. frugiperda and the non-target organisms was required. Full article

The insect innate immune system serves as the primary line of defense against pathogens, regulated by pattern recognition receptors (PRRs) such as C-type lectins (CTLs) and effector systems like prophenoloxidase (PPO). This study aims to provide molecular and functional characterization of the CTL14 and PPO4 genes from Hyphantria cunea. Cloning results revealed that CTL14 encodes 378 amino acids, whereas PPO4 encodes 681 amino acids. Expression analysis indicated that CTL14 is highly expressed during the fourth instar and within midgut tissues, while PPO4 expression is predominant during the first instar and in the epidermis. Functional assays demonstrated that silencing both genes significantly increased larval mortality following infection with the NPV virus using RNA interference (RNAi), with mortality rates reaching 75–100% by the tenth day. Furthermore, knockdown of these genes resulted in noticeable changes in larval physiology, manifested by altered feeding behavior and significantly reduced body weight gain. Conversely, the injection of CTL14 protein resulted in a marked increase in larval body mass accumulation compared to controls. These findings underscore the crucial roles of CTL14 and PPO4 as they are involved in both the antiviral defense system and the physiological development of H. cunea, thereby identifying them as potential novel targets for biological pest control strategies. Full article

Identifying conserved RNAi targets that remain effective across mosquito species and resistance backgrounds is important for developing broadly applicable mosquito control tools. Here, an engineered Escherichia coli HT115-L4440 system was used to produce β-tubulin double-stranded RNA (dsRNA), and its larvicidal activity was evaluated in susceptible and pyrethroid-resistant strains of Culex quinquefasciatus and Aedes albopictus. Recombinant bacteria produced species-specific β-tubulin dsRNA fragments of approximately 360 bp. Immersion treatment caused high larval mortality in both species. In Cx. quinquefasciatus, mortality reached 85.00% and 89.00% in susceptible and resistant strains, respectively, compared with 8.00% and 10.00% in controls, while β-tubulin transcript abundance showed maximum reductions of 571-fold and 333-fold, respectively. In Ae. albopictus, mortality reached 91.00% and 82.00% in susceptible and resistant strains, compared with 9% and 8% in controls, with maximum reductions in β-tubulin expression of 157-fold and 337-fold, respectively. These comparable effects suggest that β-tubulin dsRNA is not compromised by conventional pyrethroid-resistance mechanisms. Transcriptomic and proteomic analyses showed that β-tubulin knockdown disrupted key cellular processes, including cytoskeletal regulation, metabolism, protein synthesis, intracellular transport, detoxification, oxidative stress, DNA replication, and autophagy. Overall, engineered bacteria-derived β-tubulin dsRNA induced consistent gene silencing and larval mortality in both susceptible and resistant mosquito larvae, supporting β-tubulin as a conserved candidate RNAi target for mosquito control. Full article

The cotton bollworm Helicoverpa armigera (Hübner, 1808) (Lepidoptera: Noctuidae) is a globally distributed polyphagous pest that damages various crops. Pesticides remain a primary and effective strategy for controlling cotton bollworm populations. This study evaluated the effects of broflanilide on H. armigera by integrating life-table analysis, detoxification enzyme activity assays, and gut microbiome characterization. Broflanilide showed high toxicity against third-instar larvae. Parental LC₅₀ exposure prolonged larval development and reduced larval survival in the F₁ generation. In addition, parental exposure to both LC₃₀ and LC₅₀ reduced adult emergence, fecundity and major population growth parameters, especially the intrinsic rate of increase (r) and net reproductive rate (R₀), demonstrating a significant transgenerational inhibitory effect. Enzyme assays showed that carboxylesterase (CarE) activity was induced after broflanilide exposure, glutathione S-transferase (GST) activity showed a time-dependent response with the strongest induction generally observed under LC₁₀ treatment, whereas cytochrome P450 monooxygenase (P450) activity was generally inhibited. Gut microbiota analysis showed that LC₅₀ exposure significantly reduced the relative abundance of Enterococcus. Functional prediction further indicated enrichment trends in pathways related to xenobiotic degradation and metabolism. Overall, broflanilide not only exhibited strong lethal activity against H. armigera, but also produced sustained effects on population fitness, detoxification metabolism and gut microbial ecology. These findings provide a theoretical basis for the rational use of broflanilide and improve our understanding of its sublethal physiological and microbial effects on H. armigera. Full article