Search Results (1,022)

Background/Objectives: Mosquitoes, including Culex quinquefasciatus and Aedes aegypti, are important vectors of dengue fever, Zika virus, West Nile virus, Japanese encephalitis virus, Eastern equine encephalitis virus, etc. Biological control has always been urgent in mosquito prevention due to resistance developing to synthetic insecticides and environmental toxicity by insecticides. Methods: The leaf essential oil of Mosla. chinensis was isolated, and major components were identified via GC-MS, followed by olfactory behavior assays to evaluate its repellent activity against C. quinquefasciatus. Additionally, the odorant-binding protein 1 and odorant-binding protein 2 (CquiOBP1-2) genes were prokaryotically expressed, and their fluorescence competitive binding activities with the active components of essential oils were examined. Results: The bioassays indicated this essential oil greatly repels C. quinquefasciatus, which will significantly protect people against vector-borne diseases. In the fluorescence competitive binding experiments, the CquiOBP1-2 proteins exhibit great binding capacities to volatile components, including Citronellal, Citronellol, Geraniol, Limonene and Isopulegol. Furthermore, the behavioral experimental results also indicate that the mixture of these five ligand compounds has an obvious repellent effect on mosquitoes, highlighting that they may be applied as potential mosquito repellent agents. Moreover, molecular docking and site-directed mutation analysis further confirm Phe123 and Gln77 are both key amino acid residues of CquiOBP1-2 proteins involved in the olfactory recognition of repellent ligand compounds from M. chinensis essential oil. Conclusions: The behavioral experimental verification and the exploration of olfactory molecular mechanisms are helpful to promote the biological control of plant essential oils in mosquito pests. Full article

Thiamethoxam is the main neonicotinoid insecticide used for controlling Riptortus pedestris (Fabricius) (Hemiptera: Alydidae). However, sublethal concentration stress may induce intergenerational transcriptional memory, leading to transcriptional patterns that may contribute to the intergenerational accumulation of metabolic tolerance, and evaluating only the toxicity of the current generation would underestimate the long-term risk. Therefore, this study investigated the effect of parental exposure on the expression of detoxification enzyme genes in offspring. Using transcriptome sequencing, we systematically identified three detoxification enzyme gene families (cytochrome P450 monooxygenases (CYPs), carboxylesterases (CCEs), and glutathione S-transferases (GSTs)) in R. pedestris and compared their differential expression patterns between the parental and filial generations after thiamethoxam treatment at three sublethal concentrations (LC₁₀, LC₃₀, and LC₅₀). In the parental generation, a Theta family GST was consistently upregulated, while in the filial generation, detoxification genes were predominantly downregulated, and the genes upregulated in the parents were not also upregulated in the offspring. Comparisons of parents and offspring at the same concentration revealed that the medium concentration induced the highest number of intergenerationally upregulated genes, exhibiting a non-linear response pattern. These results indicate that parental exposure to sublethal thiamethoxam leaves an intergenerational transcriptional imprint in the offspring, and the transmission pattern involves transcriptional reprogramming rather than simple replication of the parental response, the mechanism of which remains to be determined. This study provides transcriptomic evidence for understanding the metabolic adaptation and intergenerational resistance evolution of R. pedestris to thiamethoxam, offering important reference value for field resistance monitoring and rational insecticide application. Full article

Pyrethroid insecticides are widely used in agriculture, but their sublethal effects on male reproduction in Antheraea pernyi (Guérin-Méneville, 1855) (Saturniidae) remain largely unknown. Here, we evaluated the effects of sublethal β-cypermethrin exposure (LC₂₀ = 0.0074 mg/L) on gonadal development, testicular morphology, sperm quantity and function, mating behavior, and post-mating egg traits from the larval to adult stages and investigated the molecular mechanisms using transcriptome sequencing. Insecticide stress impaired testicular development and disrupted spermatogenesis, leading to a 25% reduction in eupyrene sperm bundles, a 10.72% decrease in acrosin activity, and a 16.75% decrease in the curvilinear velocity of apyrene sperm. Mating willingness decreased by 17.78 percentage points, and females mated with treated males produced 20.45% fewer eggs. Transcriptome analysis identified 1193 differentially expressed genes (|log₂FC| > 1, FDR < 0.01). Detoxification and stress response genes (e.g., CYP3A27, GSTD1, ABCB1, and Hsp70) were predominantly up-regulated, while reproduction-related genes (e.g., dnal1, tubb1, ATPsynbeta, far1, JHAMT, mei-41, and dna2) were down-regulated. This study demonstrates that sublethal β-cypermethrin exposure induces male reproductive toxicity in A. pernyi through a “dual-hit” mechanism: persistently activating the detoxification system (leading to energy depletion) while directly suppressing reproductive genes, ultimately resulting in impaired germ cell development, defective sperm function, and reduced fertility. Full article

Essential oils obtained from Siparuna plants, e.g., S. guianensis and S. gesnerioides, have potential for use as biorational insecticides. However, the activities of S. gesnerioides oils remain largely unexplored compared to S. guianensis oils. Using an integrative approach combining toxicological bioassays, geometric morphometrics, and in silico modeling, we assessed the adulticidal potential, selectivity, and the effects of early-life exposure to these oils on the larval susceptibility and adult wing morphometry of Aedes aegypti. Adulticidal assays revealed high toxicity, with S. guianensis (LC₅₀ = 15.0 nL/mL) being 15-fold more potent than S. gesnerioides (LC₅₀ = 233.0 nL/mL). Beyond acute lethality, early-life (i.e., eggs to L2 larvae) exposure to sublethal concentrations (S. guianensis = 7.4 nL/mL and S. gesnerioides = 118.0 nL/mL) was associated with wing morphometric disruptions and increased fluctuating asymmetry in Ae. aegypti adults, especially in those exposed to S. gesnerioides essential oil. Furthermore, early-life exposure to S. gesnerioides modulated L4 larvae susceptibility, which was associated with lower mortality in subsequent exposures. Selectivity assays demonstrated low acute oral toxicity in initial laboratory screenings with Apis mellifera, while molecular docking approaches predicted higher affinity of bicyclogermacrene and α-copaene for Ae. aegypti TRPV channels. Collectively, while S. gesnerioides oil was less acutely toxic, early-life sublethal exposures reduced fourth instar larvae (L4) susceptibility, which may have contributed to developmental instability and morphological alterations in adults. Our findings highlight the potential of Siparuna essential oils in mosquito management by impacting mosquito fitness beyond acute mortality. Full article

Tetranychus urticae is a highly destructive, polyphagous mite that has developed resistance to multiple acaricides, necessitating the evaluation of new compounds. Isocycloseram is a novel insecticide with potential to control this mite; the effects of its sublethal concentrations are still uninvestigated. In this study, an age-stage, two-sex life table model was used to evaluate the sublethal effects of isocycloseram concentrations (LC₁₀ and LC₃₀) on population growth, reproduction, and development of the two-spotted spider mite. The results showed that the LC₁₀ and LC₃₀ values were 0.012 mg/L and 0.022 mg/L, respectively. Sublethal concentrations of LC₁₀ significantly affected population growth by reducing fertility, while LC₃₀ significantly prolonged the immature stage and reduced average fecundity by 37%. With the LC₃₀ treatment, the net reproductive rate R₀ decreased by 43%, and the intrinsic rate of increase r decreased significantly, from 0.152 day⁻¹ to 0.117 day⁻¹. The doubling time DT was extended by 30%, from 4.55 days to 5.92 days. This study covers the importance of life table analysis for investigating sublethal effects and for ensuring that, when isocycloseram is incorporated into integrated pest management, both its direct toxicity and its effects on population dynamics are considered. Full article

Plutella xylostella (Linnaeus) (Lepidoptera: Plutellidae) is a major cruciferous crop pest worldwide with resistance to multiple insecticide classes, highlighting the need for sustainable alternatives. Entomopathogenic fungi (EPF) are promising biocontrol agents, but their efficacy is limited by slow pathogenicity, environmental sensitivity, and low persistence on insect cuticles. This study evaluated integrated formulation strategies to enhance the virulence of Beauveria namnaoensis PM-02 against P. xylostella under laboratory and greenhouse conditions. Putative copper and zinc nanoparticle preparations were generated using fungal biomass extracts, with nanoparticle formation inferred from visual changes in the reaction mixtures. Oil-emulsified fungal formulations and combinations with emamectin benzoate were also evaluated. Larval mortality increased significantly with concentration, indicating a clear dose-dependent response. The combined treatment of oil-emulsified fungus and emamectin benzoate, along with emamectin benzoate alone, resulted in the highest larval mortality (100%), whereas fungus alone caused the lowest mortality (43.3%). Lethal concentration (LC₅₀₎ analysis indicated high toxicity of the combined treatment, while lethal time (LT₅₀) values demonstrated more rapid mortality for emamectin benzoate (0.176 days) and the combined treatment (0.830 days) compared with fungus alone (6.25 days). Under greenhouse conditions, the combined treatment showed the highest efficacy, reducing larval survival to 30% and demonstrating enhanced insecticidal activity. Overall, integrated formulation strategies significantly improved fungal efficacy against P. xylostella. Full article

The yellow mealworm (Tenebrio molitor, Linnaeus) is a cosmopolitan pest of stored grains, causing losses up to 15%. Due to the environmental and health risks of synthetic fumigants, botanical alternatives are needed, but their ecotoxicological assessment is also required. Thus, the aim of this study was to assess the insecticidal, insectistatic, and ecotoxicological effects of Salvia connivens (Epling) dichloromethane extract and to identify its compounds. Insecticidal and insectistatic activities were assessed through the consumption of an artificial diet containing the extract over 30 days. Ecotoxicological activity was evaluated through acute toxicity assays on Danio rerio (Hamilton) adults and embryos. The extract showed insecticidal activity against T. molitor achieving 50% mortality at 10,000 ppm (LC₅₀ = 9367.19 ppm). Additionally, at 10,000 ppm larval weight gain was reduced by 53.37% at 30 days compared to the control. Ecotoxicological assays revealed slight toxicity toward D. rerio adults (LC₅₀ = 84.27 ppm) and embryos (LC₅₀ = 32.60 ppm). GC-MS analysis identified hexadecanoic acid (7.08%), 1-(2-methoxyphenyl)-2,5-dihydro-1H-pyrrole-2,5-dione (6.30%), cis-9-octadecenoic acid (3.91%), β-sitosterol (3.05%), and eicosane (3.00%) as the major constituents according to the chromatographic method used. These findings suggest that S. connivens dichloromethane extract is a potential botanical product for T. molitor management. Full article

Lepidopteran pests cause severe global economic damage; they are currently mitigated by synthetic pesticides that trigger widespread resistance and environmental toxicity. This systematic review evaluates the potential of Piper essential oils (EOs) as high-performance, sustainable bio-based insecticides, aligning with the 12 Principles of Green Chemistry. Analyzing studies covering Piper species, we identified phenylpropanoids (e.g., dillapiole and safrole) and terpenoids as key biodegradable scaffolds for pest management. The results highlight P. aduncum and P. divaricatum for their exceptional efficacy against Spodoptera frugiperda and Plutella xylostella, often exhibiting toxicity levels comparable to botanical standards like azadirachtin. Crucially, this review reveals that Piper EOs can outperform the synthetic industrial synergist piperonyl butoxide (BPO), with natural binary mixtures enhancing insecticidal potency by up to 11-fold. Furthermore, specific EOs contribute to a preventative green strategy by causing the structural disintegration of the egg chorion. By focusing on renewable biomass and design for degradation (Principles 7 and 10), this work anchors the Piper genus as a cornerstone for the circular bioeconomy and sustainable agricultural innovation, reducing the chemical footprint of modern crop protection. Full article

Pine wilt disease control often depends on reducing adult beetle activity, but how aerial spraying performs under operational forest management conditions remains poorly understood. We evaluated a 2022 operational aerial spray program in Pinus thunbergii stands in Shandong, China, by combining droplet deposition measurements, branch-feeding bioassays to assess acute and residual toxicity with Monochamus alternatus, and seasonal trap monitoring of both M. alternatus and Arhopalus rusticus, a relevant co-occurring cerambycid species. Spray cards showed that insecticide reached the stand in both spray rounds, although vertical differences between upper and lower strata were stronger during the second application. Branches collected immediately after spraying caused rapid mortality of M. alternatus, and both strata reached complete mortality within 72 h of exposure. In contrast, branches collected one month later caused little additional mortality beyond control levels, indicating that biologically effective exposure declined quickly and provided an insufficient window of protection relative to the full period of adult beetle activity. Trap data matched this pattern. After the first spray, M. alternatus captures dropped sharply during the immediate post-spray period but rebounded before the second spray. A. rusticus showed a similar short-term response, but its seasonal activity pattern differed from that of M. alternatus. Overall, the main limitation of the spray program was not weak initial toxicity, but the short duration of effective control relative to beetle activity in the field. This study shows that better aerial control of pine wilt vectors will depend on matching spray timing and residual persistence with local beetle phenology to improve the design and timing of aerial control programs in pine wilt management. Full article

EpOMEs suppress excessive and unnecessary immune responses at late infection stage in insects. This immune resolvin activity of EpOMEs includes the cell lysis of hemocytes by causing apoptosis. This cytolytic toxicity of EpOMEs suggests a potential insecticidal activity of their stable analogs. In fact, a propoxy derivative of 12,13-EpOME called AS56 mimicked EpOME activity by suppressing immune responses and exhibited insecticidal activity against a lepidopteran insect, Spodoptera exigua. This study evaluated the potency of the EpOME analogs by modifying their functional groups. PD28 is a racemic mixture of propoxy analog at the twelfth carbon. FD25 is a racemic butoxy mixture at the twelfth carbon of AS56. AS61 is saturated at the ninth carbon of AS56. The effects of the EpOME analogs were assessed on two cellular immune responses: hemocyte-spreading and nodule formation. All four analogs inhibited the cellular immune responses; however, AS56 was the most potent in inhibiting the immune responses. FD25 and AS61 were significantly less potent compared to AS56, suggesting crucial roles of the double bond at the ninth carbon and the propoxy chain at the twelfth carbon. The stronger inhibitory activity of AS56 compared to PD28 also suggests the functional role of the stereoisomeric form in physiological functions. The cytotoxicity of AS56 was also the most potent among the analogs, suggesting its insecticidal activity. Subsequent insecticidal bioassays on AS56 toxicity were performed against different insect species. These EpOME analogs were potent against lepidopteran insects (S. exigua and Plutella xylostella) but not against coleopteran (Tenebrio molitor) or thysanopteran (Frankliniella occidentalis) species. Among the EpOME analogs, AS56 was the most toxic against the lepidopteran insects. Spraying AS56 in cabbage fields infested by lepidopteran insects led to acute and high control efficacy against two lepidopteran pests, similar to that of a chemical insecticide, fluxametamide. The AS56-intoxicated larvae exhibited over-excitation in their behavior around 12 h post-treatment. This study indicates that AS56 exhibits an oral toxicity against lepidopteran insects with its cytotoxicity and behavioral over-excitation. Full article

Although information on insecticide toxicity on pests abounds, this is limited on non-target organisms like ants in cocoa production systems. This study determined the toxicity of insecticides (containing acetamiprid 40 g L⁻¹ EW, acetamiprid 64 g L⁻¹ + emamectin benzoate 48 g L⁻¹ EC, acetamiprid 20 g L⁻¹ + lambda-cyhalothrin 15 g L⁻¹ SC, emamectin benzoate 5% WDG and pyrethrins 50 g L⁻¹ EW) used against cocoa pests on non-target predatory ants (Crematogaster africana, Oecophylla longinoda and Pheidole megacephala) under laboratory (using filter-paper method) and field conditions to identify less harmful products for use in the cropping system. Ant knockdown and mortality varied significantly among insecticides at their recommended rates, with emamectin benzoate being the least toxic and acetamiprid + lambda-cyhalothrin the most toxic. LC₉₅s varied significantly, with emamectin benzoate having the highest predator safety index, while pyrethrins had the lowest. Generally, selectivity towards O. longinoda was higher than that towards the other ants. In the field, emamectin benzoate had the least acute adverse effect on ant abundance. Ant population generally rebounded to pre-treatment levels at 1 month after the last insecticide application. The study indicates differential toxicity and identifies ant-compatible insecticide options contingent on the autochthonous ant composition. Full article

The fall armyworm (Spodoptera frugiperda), a highly destructive invasive Lepidopteran pest, poses a serious threat to global agriculture, particularly maize production. Plant essential oils (EOs) represent a promising class of botanical pesticides owing to their diverse bioactivities and low environmental persistence. In this study, we evaluated the insecticidal and antifeedant activities of 40 commercially available EOs against third-instar S. frugiperda larvae. After an initial screening at 4 μL/mL, 10 EOs that caused ≥70% mortality at 72 h were selected for bioassays to estimate LC₅₀ value and chemical analysis by GC-MS. Contact toxicity assays showed that geranium EO had the highest activity (LC₅₀ = 2.105 μL/mL at 72 h), followed by cypress (2.123 μL/mL) and niaouli (2.391 μL/mL), whereas tea tree EO exhibited the lowest activity (3.592 μL/mL). Antifeedant tests revealed that clove EO caused the strongest feeding deterrence at both 24 h (antifeedant indices AFI = 72.8%) and 48 h (AFI = 63.4%), while most other EOs lost their deterrent effect within 48 h. GC-MS analysis of the 10 active EOs identified a complex mixture of monoterpenes, sesquiterpenes, and oxygenated derivatives; major constituents included D-limonene, 4-terpineol, carvacrol, caryophyllene, and longifolene. These results provide laboratory evidence that several plant EOs, particularly geranium, cypress, niaouli, and clove, possess strong insecticidal and antifeedant activities against S. frugiperda larvae, supporting their potential as eco-friendly botanical insecticides. Full article

Athetis lepigone (Möschler) is an important pest of maize in North China, whose larvae feed mainly on maize leaves, stems, and roots during the seedling stage, with conventional maize lacking effective resistance to it. In recent years, transgenic Bt maize expressing Cry1Ab and Vip3Aa proteins has been commercialized in China; however, its resistance against A. lepigone has not yet been systematically evaluated. In this study, three Bt maize events, DBN3601T expressing Cry1Ab and Vip3Aa, DBN9936 expressing Cry1Ab, and DBN9501 expressing Vip3Aa, were used to comprehensively assess resistance against the pest based on Bt protein expression levels in different maize tissues, larval susceptibility across instars, and larval feeding behavior under controlled laboratory conditions. The results showed that Bt protein expression varied significantly among maize tissues commonly fed upon by the insect, following the general pattern: seedling leaf > stem > root. Bioassays using artificial diets incorporated with freeze-dried maize leaf powder indicated that larvae were significantly more susceptible to Cry1Ab than to Vip3Aa, with LC₅₀ values of 1.05 and 2.65 μg·g⁻¹, respectively. Maize co-expressing both proteins exhibited high insecticidal activity. First-instar larvae displayed feeding avoidance of Bt maize tissues, and early instars were more sensitive than later instars; however, stems and roots showed stronger toxicity to older larvae. In simulated field infestation assays, the control efficacies of DBN3601T, DBN9936, and DBN9501 reached 94.35%, 88.79%, and 10.56%, respectively, at five days post-infestation. Overall, DBN3601T maize exhibited a strong resistance performance against A. lepigone, indicating strong potential for pest management applications. Full article

Bradysia odoriphaga is a devastating soil pest of Allium tuberosum (Chinese chive), and current control relies heavily on chemical insecticides. Cry39Ab1 toxins from Bacillus thuringiensis (Bt), which are highly toxic to B. odoriphaga, offer an environmentally friendly alternative. However, its mechanism of action remains unclear. In this study, we identified the involvement of vacuolar H⁺-ATPase subunit A (V-ATPase A) in Cry39Ab1 insecticidal activities. The full-length cDNA sequences of BoV-ATPase A was contained 1659 bp open reading frame (ORF), encoding a protein of 552 amino acids with a calculated molecular weight of 59 kDa and an isoelectric point of 9.11. Successful expression and purification of BoV-ATPase A (with GST and His tags) and Cry39Ab1 (with GST and His tags) proteins were achieved. GST pull-down assays demonstrated a direct interaction between recombinant BoV-ATPase A and activated Cry39Ab1 toxin in vitro. Heterologous expression of BoV-ATPase A in Cry-insensitive Sf9 cells conferred susceptibility to Cry39Ab1, resulting in a significant increase in cytolysis compared with control cells. Finally, RNAi-mediated knockdown of BoV-ATPase A in larvae significantly decreased their susceptibility to Cry39Ab1, as evidenced by a marked decrease in mortality. This is the first report that BoV-ATPase A is a key protein required for Cry39Ab1 toxicity, revealing its insecticidal mechanism and establishing BoV-ATPase A as a potential target for pest control. Full article

Although the effectiveness of plant-derived essential oils (EOs) against several insect pests is well-documented, their high volatility presents a challenge. In this study, the potential to enhance the insecticidal activity of Satureja hortensis L. EO, an accessible natural agent, through nanoemulsification was assessed against the cosmopolitan pest Spodoptera frugiperda (J. E. Smith, 1797). The nanoemulsion of the EO (NEEO) was prepared using Tween 80 as the emulsifying agent and high-intensity ultrasonication. Oral bioassays indicated that the NEEO was more toxic (LC₅₀ = 0.922%) than the pure EO (LC₅₀ = 1.186%). Sublethal exposure to LC₃₀ of the NEEO caused evident reductions in preadult survival, developmental time, fecundity, and oviposition period, as well as the population growth parameter net reproductive rate (R₀). The exposure to the NEEO increased catalase (CAT), glutathione S-transferase (GST), and superoxide dismutase (SOD) actions and inhibited α-esterase (α-NE), β-esterase (β-NE), and cytochrome P450 (CYP450) actions. Both the NEEO and EO inhibited acetylcholinesterase (AChE) and Na⁺/K⁺-ATPase, with higher inhibition in the NEEO group. Generally, S. hortensis NEEO enhanced toxicity, intensified physiological perturbations, and caused greater negative impacts on population growth parameters. Consequently, nanoemulsification of S. hortensis EO can be considered an effective method to strengthen the insecticidal potential of this natural agent. Full article