Search Results (106)

Chinese wolfberry (Lycium barbarum L.), a specialty crop with ecological, medical, and economic value in Ningxia province of China, is subject to severe damage from Aphis gossypii Glover. Currently, A. gossypii populations show extremely high-level resistance to beta-cypermethrin in the major wolfberry planting areas in Ningxia. The specific resistance mechanisms, however, are still not known. In this work, we collected a field A. gossypii strain (HSP) from a wolfberry orchard in Ningxia in 2021 using a single-time sampling method, and its resistance to beta-cypermethrin was determined to be extremely high (994.74-fold) as compared with that of a susceptible strain (SS). Then we explored the potential resistance mechanisms from two aspects, namely, metabolic detoxification and target-site alterations. Bioassays of beta-cypermethrin with or without a synergist showed that piperonyl butoxide (PBO) significantly increased the toxicity of beta-cypermethrin (4.72-fold) to the HSP strain, while triphenyl phosphate (TPP) and diethyl maleate (DEM) exhibited no significant synergistic effects. Correspondingly, the O-demethylase activity of cytochrome P450s in the HSP strain was 1.68-fold higher than that in the susceptive strain (SS), whereas changes in carboxylesterases and glutathione S-transferases activities were unremarkable. Also, fifteen upregulated P450 genes were identified by both RNA-Seq and qRT-PCR technologies, containing eleven CYP6 genes, three CYP4 genes, and one CYP380 gene. Especially, five CYP6 genes with high relative expression levels (>3.00-fold) were intensively expressed by beta-cypermethrin induction in the HSP aphids. These metabolism-related results indicate the key role of P450-mediated metabolic detoxification in HSP resistance to beta-cypermethrin. Sequencing of voltage-gated sodium channel (VGSC) genes identified a prevalent M918L mutation and a new G1012D mutation in HSP A. gossypii. Moreover, heterozygous 918 M/L and 918 M/L + G1012D mutations were the dominant genotypes with frequencies of 60.00% and 36.67% in the HSP population, respectively. Overall, VGSC mutations along with P450-mediated metabolic resistance contributed to the extremely high resistance of the HSP wolfberry aphids to beta-cypermethrin, providing support for A. gossypii control and resistance management in the wolfberry planting areas of Ningxia using insecticides with different modes of action. Full article

Nuclear receptors are a family of ligand-dependent transcription factors that regulate the development, reproduction, survival, and immune responses in insects. However, the structural, biological, and molecular functions of hepatocyte nuclear factor 4 (HNF4) in aphids remain unknown. Aphids are small agricultural pests that directly affect crops due to their rapid reproductive ability, which is influenced by environmental conditions such as temperature, humidity, and photoperiod. In this study, we cloned full-length cDNA encoding HNF4 from the cotton aphid Aphis gossypii (A. gossypii, Hemiptera: Aphididae) (AgHNF4) and investigated its role in regulating lipid metabolic gene expression, aphid survival, and reproduction. Phylogenetic analysis revealed that AgHNF4 shares an evolutionary lineage with other hemipteran insects. The ligand binding domain region of AgHNF4 showed significance in nuclear localization and transcriptional activity. The expression pattern of AgHNF4 was detected in the stages of the aphid life cycle, with notable expression during the 2nd instar, 4th instar, and adult stages. Furthermore, to understand the role of HNF4 in regulating lipid metabolic genes involved in fatty acid synthesis and transport, HNF4-silenced A. gossypii individuals were analyzed. The results showed downregulation of lipid metabolic genes and reduced offspring production and survival rates. Therefore, A. gossypii HNF4 serves as a potential target for regulating lipid metabolism, and targeting HNF4 expression could offer a promising approach to aphid pest control. Full article

Symbiotic bacteria in insects are known to play crucial roles in detoxification metabolism and adaptation to host plant secondary metabolites. In the cotton-growing region of Xinjiang, China, the Ap. gossypii and the Ac. gossypii exhibit significant differences in sensitivity or resistance to pesticides. However, whether their detoxification-related symbiotic bacteria change under insecticide stress remains unclear. This study assessed the toxicity of nitenpyram to both aphid species and the effects of LC₂₀ treatment on their growth, development, and reproduction. Bacterial community dynamics across generations (G0–G2) were analyzed by 16S rRNA gene amplicon sequencing. The LC₂₀ of nitenpyram reduced the longevity and fecundity of the parent generation in both species. In Ap. gossypii, the intrinsic rate of increase (r_m), net reproductive rate (R₀), and finite rate of increase (λ) increased in the G1–G2 generations, whereas these parameters significantly decreased in Ac. gossypii. By the G3 generation, biological parameters in both species showed no significant differences compared to the control. Nitenpyram disrupted the stability of symbiotic bacterial communities in both aphids. In Ac. gossypii, Sphingomonas, a genus with detoxification potential, was consistently suppressed in G1–G2, while the abundance of the primary symbiont Buchnera initially decreased sharply and subsequently recovered. In contrast, the bacterial community in Ap. gossypii remained largely stable. These findings indicate that sublethal concentrations of nitenpyram exert distinct transgenerational effects on the two aphid species and disrupt the stability of their symbiotic bacterial communities. Full article

(1) Objective: To investigate the chemical defense response mechanisms of two cotton (Gossypium hirsutum L., Malvaceae) varieties, Xinlu Zhong 57 and Xinlu Zhong 78, in response to feeding by the cotton aphid (Aphis gossypii Glover, 1877) (Hemiptera: Aphididae) in the Kashi region. (2) Methods: The artificial infestation method was adopted to determine the dynamic changes in the contents of secondary metabolites (tannins, total phenols), activities of protective enzymes (SOD, POD, PPO), and contents of nutrients (soluble sugars, amino acids) in cotton leaves at 0, 24, 48, 72, and 96 h after infestation with cotton aphids. (3) Results: The contents of secondary metabolites and the activities of protective enzymes in both varieties showed an initial increase followed by a decrease. The response of Xinlu Zhong 57 was earlier and stronger. Its tannin and total phenol contents reached a peak at 48 h, with values of 264.2 nmol/g and 5.973 mg/g, respectively, which were significantly higher than those of Xinlu Zhong 78 (p < 0.05). The activities of SOD, POD, and PPO were consistently higher in Xinlu Zhong 57. At 48 h post-inoculation, SOD activity in Xinlu Zhong 57 was 238.1 U/g, significantly higher than in Xinlu Zhong 78 (p < 0.05). POD activity was 49.0 U/g, and PPO activity was 94.5 U/g, both significantly higher than those of Xinlu Zhong 78 (p < 0.05). This suggests that Xinlu Zhong 57 has a stronger ability to scavenge reactive oxygen species. Regarding nutrients, soluble sugar content in Xinlu Zhong 57 was 6.99 mg/g at 96 h, significantly higher than that in Xinlu Zhong 78 (p < 0.05). The amino acid content at 96 h was 224.4 μg/g, also significantly higher than in Xinlu Zhong 78 (p < 0.05). (4) Conclusions: Xinlu Zhong 57 forms a more effective chemical defense system by rapidly activating the defense enzyme system, efficiently accumulating secondary metabolites, and optimizing nutrient allocation. This study provides a theoretical basis for elucidating the physiological mechanisms of cotton resistance induced by cotton aphids by analyzing the effects of cotton aphid stress on the contents of secondary metabolites, protective enzyme activities, and nutrient contents in cotton leaves. Full article

A total of 304 bacterial strains were isolated from the Taklamakan Desert. Through screening, strain TRM82367 exhibited potent insecticidal activity against cotton aphids (Aphis gossypii) and was identified as Bacillus velezensis. To explore the primary insecticidal active components of this strain, lipopeptide substances in the fermentation broth were extracted via hydrochloric acid precipitation. The main active components were analyzed using activity-guided fractionation combined with liquid chromatography–mass spectrometry (LC-MS). Our results demonstrated that Bacillus velezensis TRM82367 possessed strong lethal activity against cotton aphids. The crude extract obtained by means of hydrochloric acid precipitation and methanol dissolution showed high insecticidal efficacy. At concentrations of 100, 150, 200, 250, 300, 400, and 500 mg/L, the 48 h corrected mortality rates of cotton aphids were 25.14%, 38.05%, 50.09%, 53.03%, 57.96%, 74.68%, and 88.67%, respectively. The toxicity regression equation was Y = 2.47X − 5.72, with a median lethal concentration (LC₅₀) of 207.616 mg/L and a 95% lethal concentration (LC₉₅) of 1004.673 mg/L. After separation by an ODS chromatographic column and identification by means of mass spectrometry, the main active components were confirmed to be C₁₂–C₁₆ surfactin homologs. Full article

The cotton aphid Aphis gossypii is a globally significant agricultural pest that threatens crop production through its prolific reproduction. While the parasitoid wasp Binodoxys communis offers promising potential for biological control, the molecular mechanisms underlying its reproductive manipulation of aphid hosts remain poorly understood. Here, we investigated the stage-specific parasitism strategies of B. communis on A. gossypii using integrated biological observations and transcriptomic analysis. Parasitism significantly prolonged aphid development and suppressed reproduction across all host stages, with severity inversely correlated with host age at parasitism. Transcriptomic analysis of ovaries of parasitized aphids revealed 1168 differentially expressed genes, with temporal progression from minimal changes in nymphs (7 DEGs at day 1) to extensive disruption in adults (549 DEGs at day 3). Notably, juvenile hormone acid methyltransferase (JHAMT), the rate-limiting enzyme in juvenile hormone biosynthesis, emerged as a master regulator that is differentially targeted across host stages. In 3rd instar nymphs, single-gene suppression of JHAMT (−3.23-fold change) achieved effective reproductive control, whereas adult parasitism required progressive manipulation of multiple genes including JHAMT, FOHSDR, ALDH, and JHEH. The vitellogenin-vitellogenin receptor system only showed coordinated downregulation in adults, whereas nymphs exhibited preemptive receptor suppression before vitellogenesis onset. These findings demonstrate that B. communis has evolved to exploit a developmental window where host manipulation is most efficient—3rd instar nymphs, which possess sufficient resources for parasitoid development and lack the complex compensatory mechanisms found in adults. This “low-cost, high-reward” strategy based on precision targeting of master regulators in nymphs compared to multi-gene assault in adults, revealing the evolutionary optimization of parasitoid manipulation strategies. Our results provide molecular insights into parasitoid-host coevolution and identified key regulatory targets for developing innovative biological control strategies against this important agricultural pest. Full article

Aphis gossypii is a major pest that harms crops like industrial tomatoes in Panama. Recent resistance to synthetic insecticides has prompted interest in using plant secondary metabolites as eco-friendly alternatives. While some plants with insecticidal properties are well-known, others remain unexplored but could offer effective solutions. This study aimed to evaluate the insecticidal activity of ethanolic extracts from the stems and leaves of Eschweilera jefensis against nymphs and adults of Aphis gossypii. Extracts were tested at three concentrations (25, 50, and 100 µg/L), with mortality assessed at 24, 48, and 72 h post-application. The LC₅₀ values for the stem extract were 66.5, 36.8, and 31.0 μg/L, and for the leaf extract, they were 37.3, 28.4, and <25 μg/L at 24, 48, and 72 h, respectively. An advanced metabolomic analysis was conducted to identify the active compounds in each extract. This analysis uncovered several pentacyclic triterpenes, which, known for their insecticidal properties, are likely the key bioactive components responsible for the observed effects. Advanced metabolic analyses also revealed that the leaf extract, displaying the strongest insecticidal activity, is primarily composed of friedelin, while the stem extract contains betulin as their key active compounds. Furthermore, 29 known compounds were identified across both extracts, representing the first comprehensive report on the metabolic composition of E. jefensis, which underscores the significance of these findings. Together, these results suggest that E. jefensis extracts could serve as a promising natural alternative to synthetic insecticides for the management and control of A. gossypii. Full article

The aphid, Aphis gossypii Glover, and the leaf beetle, Lema decempunctata Gebler, are two catastrophic pests affecting the production of the organic goji berry, Lycium barbarum L. Our previous studies have demonstrated that the defense responses of goji berry induced by aphid infestations can facilitate the growth and development of beetles. However, the reciprocal effects of these two insect infestations on aphids remained unclear. In this study, the impacts of these two pest infestations on the development, survival, and reproduction of aphids were examined. Additionally, the levels of plant defense-related hormones, salicylic acid (SA) and jasmonic acid (JA), were measured. Subsequently, host plants were treated with two hormone analogues, 2, 1, 3-benzothiadiazole (BTH) and methyl jasmonate (Me-JA), to identify their effects on aphid development, survival, and reproduction. The results showed that the total developmental duration was accelerated by 33.60%, and the total reproduction of aphids was increased by 82.98% compared to the control after aphid infestation, without influencing survival. In contrast, the beetle infestation did not significantly influence any aspect of the aphid population. The content of SA in plants after the aphid infestation and JA after the beetle infestation increased 19.42 times and 400.50 times, respectively, compared with the control. The total developmental duration of aphids treated with BTH was reduced by 13.44%, while their reproduction increased by 60.52% compared with the control. The total developmental duration of aphids treated with Me-JA was prolonged by 23.51% compared to the control, while survival rates and reproduction were unchanged. Our research elucidates the intricate interspecific relationship between A. gossypii and L. decempunctata, providing valuable insights into the complex interspecific relationship between the two pests and informing effective strategies for their scientific prevention and control. Full article

The cotton aphid, Aphis gossypii Glover, is among the most economically significant sap-sucking insect pests, inflicting substantial economic losses worldwide. Insecticides such as thiamethoxam, bifenthrin, and flonicamid are commonly used to manage this pest, despite the inherent risk of developing resistance. In this study, we investigated the evolution of insecticide resistance in A. gossypii after continuous selection with thiamethoxam, bifenthrin, and flonicamid over more than ten generations in a controlled laboratory environment. We assessed the fitness of resistant strains using an age-stage, two-sex life table approach, comparing them to a susceptible population. The results indicated that A. gossypii achieved resistance levels of 158.60-fold against thiamethoxam, 129.18-fold against bifenthrin, and 104.75-fold against flonicamid. Furthermore, life table analyses revealed that the developmental stages were significantly extended, while longevity decreased in all resistant strains compared to the susceptible population. Additionally, the net reproductive rate (R₀), fecundity, and reproductive days were notably reduced in the resistant cohorts when compared to the susceptible strain. Overall, these findings provide valuable insights into the laboratory-induced evolution of insecticide resistance and the associated fitness costs in A. gossypii when feeding on cotton plants. This information could be instrumental in formulating effective resistance management strategies to control this significant pest. Full article

Aphis gossypii is a significant global pest that impacts numerous agricultural crops and vegetables, causing direct damage to food plants and indirect damage through the transmission of phytopathogenic viruses, primarily begomoviruses. In Panama, particularly in the Azuero region, viral infections transmitted by this aphid can affect a substantial share of tomato crops cultivated for industrial use. A traditional alternative to synthetic pesticides involves exploring plant extracts with insecticidal properties derived from wild plants found in our tropical forests, which can be easily prepared and applied by farmers. In this context, the present research aimed to evaluate the insecticidal activity of ethanolic extracts from the stems and leaves of Sphagneticola trilobata on both nymphs and adults of A. gossypii. Mortality was assessed at 24, 48, and 72 h after applying three doses of each extract (25, 50, and 100 µg/L). A standard phytochemical analysis to determine insecticidal activity revealed that both extracts exhibited significant efficacy at the highest concentration tested; however, the leaf extract demonstrated greater effectiveness at lower concentrations. A comprehensive metabolomic study indicated that the active compounds are diterpenes derived from the pimarenyl cation. These compounds have been extensively documented for their insecticidal potential against various insect species, suggesting that ethanolic extracts from this plant could serve as viable candidates for agricultural insecticides to combat aphid infestations. Full article

Self-emulsifying solid nanodispersion technology is emerging as an attractive strategy to prepare new eco-friendly and efficient nano-formulations due to its simple, energy efficient and easy scale-up process. However, it is still unknown whether this technology can be employed to cope with the drawbacks of botanical insecticides including poor water solubility, rapid photodegradation and limited targeting efficiency. In this study, rotenone (Rot) was selected as a model of botanical insecticides, and its solid nanodispersion (Rot–SND) was prepared by a self-emulsifying method combined with parameter optimization. Our target nano-formulation, consisting of 5% Rot, 20% surfactant complexes of 8% Ethylan 992 and 12% EL–80, and 75% lactose, exhibited excellent storage stability and significantly improved the pseudo-solubility of Rot by at least 250 times. The average particle size and polydispersity index (PDI) of Rot–SND were determined to be 101.19 nm and 0.21, respectively. Rot–SND displayed smaller contact angles and greater retention on both cucumber and cabbage leaves than those of a commercial emulsifiable concentrates (ECs). Rot–SND was also more resistant to photodegradation, with a degradation rate reduced by 27.01% as compared with the ECs. In addition, the toxicity of Rot–SND towards Aphis gossypii was 3.01 times that of the ECs, with a median lethal concentration (LC₅₀) of 1.45 µg a.i./mL. Under the field conditions, Rot–SND showed a prolonged duration for A. gossypii control, with a significantly higher control efficacy (88.10%) on the 10th day than that of the ECs (77.02%). Moreover, a 2.34-fold decline in the toxicity towards nontarget mosquito larvae was observed for Rot–SND as compared with the EC. Overall, for the first time, our results indicate the role of Rot–SND as an eco-friendly and efficient way to improve the solubility, foliar affinity, photostability, bioactivity and eco-safety of Rot. This research also provided a feasible strategy to prepare more eco-friendly botanical pesticide formulations of high efficiency. Full article

The cotton aphid, Aphis gossypii, is a globally significant agricultural pest whose microbiota plays vital roles in its physiology and adaptation. However, the dynamics of bacterial communities across its developmental stages remain poorly understood. This study employed full-length 16S rRNA gene sequencing to characterize the microbiota structure, diversity, and functional potential in nine developmental stages of A. gossypii, including egg, nymph (1-, 3-, 5-, 7-day-old), and adult (1-, 3-, 5-, 7-day-old). Results revealed Proteobacteria (72.75–95.51%) as the dominant phylum across all stages, with Buchnera aphidicola (primary obligate symbiont) constituting over 23.83% of bacterial abundance and peaking in eggs (≈80%). Alpha diversity indices (Shannon, Simpson) indicated significantly higher microbial diversity in nymphs compared to adults, suggesting stage-specific ecological interactions. While beta diversity analysis showed no structural clustering by developmental stage, functional predictions highlighted enrichment in metabolic pathways (>73% of genes), though limitations in 16S-based functional inference were noted. Notably, facultative symbionts like Hamiltonella or Serratia were absent, contrasting with other aphid systems. Dynamic shifts in Buchnera titer and the prominence of Delftia tsuruhatensis and Enterobacter hormaechei implied potential roles in host adaptation. These findings highlight the persistent dominance of the obligate symbiont Buchnera aphidicola across all developmental stages, despite quantitative fluctuations in its abundance, alongside stage-specific shifts in facultative bacterial communities, offering insights into novel targets for microbiome-driven pest management strategies. Further multi-omics approaches are warranted to validate functional contributions of these microbial communities. Full article

The polyphagous aphid Aphis gossypii exhibits host-specific biotypes, notably the cotton (Hap1) and cucumber (Hap3) types. While both can adapt to new hosts via zucchini induction, the underlying molecular mechanisms remain unclear. Our investigation revealed that both Hap1 and Hap3 A. gossypii underwent significant body size enlargement following host transfer to zucchini. Transcriptomic analysis revealed that zucchini-mediated host adaptation in the A. gossypii biotypes (Hap1/Hap3) involves insulin metabolism and detoxification pathways, with 17 co-differentially expressed genes (e.g., Col-I (type I collagen), CYP450 6a13, peroxidase) potentially critical for adaptation. The findings provide new insights into the molecular mechanisms regulating A. gossypii phenotypic plasticity and contribute to the development of resistance management strategies. Full article

Expanding genetic variability of cultivated cotton (Gossypium hirsutum) is essential for improving fiber quality and pest resistance. This study synthesized allotetraploids through interspecific hybridization between G. herbaceum (A₁) and G. nelsonii (G₃). Upon chromosome doubling using 0.2% colchicine, fertile F₁C allotetraploids (A₁A₁G₃G₃) were developed. Cytogenetic analysis confirmed chromosome stability of synthetic allotetraploids, and 74 polymorphic SSR markers verified hybridity and parental contributions. The F₁C hybrids exhibited enhanced resistance to cotton aphids (Aphis gossypii) and whiteflies (Aleyrodidae), with respective infestation rates of 5.2–5.6% and 5.4–5.8%, lower than those of G. hirsutum cv. Ravnak-1 (22.1% and 23.9%). Superior fiber length (25.0–26.0 mm) was observed in complex hybrids and backcross progeny, confirming the potential for trait introgression into elite cultivars. Phylogenetic analysis based on SSR data clearly differentiated G. herbaceum from Australian wild species, demonstrating successful bridging of divergent genomes. The F₁C hybrids consistently expressed dominant G. nelsonii-derived traits regardless of the hybridization direction and clustered phylogenetically closer to the wild parent. These synthetic allotetraploids could broaden the genetic base of G. hirsutum, addressing cultivation constraints through improved biotic stress resilience and fiber quality traits. The study establishes a robust framework for utilizing wild Gossypium species to overcome genetic bottlenecks in conventional cotton breeding programs. Full article

Gynopara is a specific winged type in the life history of Aphis gossypii. As a key reproduction mode between parthenogenesis and sexual reproduction, it lays sexual females in late autumn. However, little is known about gynoparae because of its rare presence in the wild and the lack of its detailed descriptions. In this study, we investigated the morphological characteristics, ovary maturation process, and key signaling pathways during the development of gynoparae of A. gossypii. With the extension of development stage, the gynoparae exhibited gradually enlarged and thickened abdomen, deepened color. Obviously differentiated wing primordia in the second instar nymphs. Two nested U-shaped zones containing a series of waxy secreta spots were present on the abdomen of the fourth instar nymphs, and these morphological characteristics could be used as important markers for identifying gynoparae. Temporal transcriptomic analysis suggested that juvenile hormone (JH) might be involved in regulating the development of gynoparae. After the application JH analog kinoprene to the first instar nymphs, almost all treated individuals failed to complete wing differentiation, and most lost the ability to produce progeny, suggesting the destructive effect of JH on wing differentiation and reproduction of gynoparae. Moreover, exogenous addition of kinoprene also significantly altered the expression levels of four key genes responsible for the synthesis and degradation of JH. Our findings reveal the mechanism by which JH regulated wing differentiation and reproductive capacity of gynoparae, which lay a foundation for the further research on reproduction mode switch in aphids in the future. Full article