Pest Management Science最新文献

Background: Interactions between parasitic insects and their hosts demonstrate the complexity of evolutionary processes. Specifically, the parasitoid wasp Aphidius ervi manipulates its host, the pea aphid Acyrthosiphon pisum, through strategic venom injection to enhance mummification. This study explores how this venom affects the aphid's immune system, particularly targeting the activity of the phenoloxidase (PO) enzyme.

Results: Following the injection of venom from A. ervi, significant changes were observed in the expression of immune-related genes in A. pisum, especially notable expression changes of ApPPOs and a reduction of PO activity. Multi-omics sequencing identified 74 potential venom proteins in the venom gland of A. ervi, including serine protease homolog 1 (AeSPH1) and serine protease inhibitor (AeSPN1), hypothesized to regulate PO activity. The injection of recombinant protein AeSPH1 and AeSPN1 into the A. pisum hemocoel selectively reduced the expression of ApPPO1, without affecting ApPPO2, and effectively suppressed melanization. Moreover, RNAi targeting AeSPH1 significantly reduced the mummification rate in A. pisum population parasitized by A. ervi.

Conclusion: Our findings clarify the complex biochemical mechanisms underlying host-wasp interactions and highlight potential avenues for developing targeted biological control strategies. © 2024 Society of Chemical Industry.

Background: Reproduction is the basis of insect population growth and evolution, and encompasses ovarian development, reproductive behavior, and fecundity. Bactrocera dorsalis is a globally significant agricultural pest that is subject to quarantine, with mated females that can lay over 3000 eggs. The post-transcriptional regulation of ovarian development remains unclear. Here, miR-31b is shown to be involved in regulating Bactrocera dorsalis ovarian development.

Results: CRISPR/Cas9 was used to generate miR-31b loss-of-function mutations in Bactrocera dorsalis. The removal of miR-31b resulted in severely impaired ovarian development in adults, with phenotypes that included dramatically reduced egg production and hatching rates. The relationship between miR-31b and its target gene arylsulfatase B (ARSB) was subsequently identified using the methods of bioinformatics, transcriptomic sequencing, quantitative polymerase chain reaction (qPCR), RNA pull-down and dual-luciferase reporter assay. Finally, miR-31b was confirmed to bind the target gene arylsulfatase B to affect metabolism and thereby further hindered ovarian development of Bactrocera dorsalis.

Conclusion: Overall, these results provide new insights into molecular mechanisms at the post-transcriptional level in regulating ovarian development and insect reproduction, consequently providing potential targets to control arthropod pests through the reproductive strategy. © 2024 Society of Chemical Industry.

Background: Gray mould caused by Botrytis cinerea, an airborne phytopathogenic pathogen, infects many economically important fruits and vegetables. Secondary metabolic products of microorganisms are potential resources for developing fungicide alternatives. Venturicidin A (VentA) is produced by a biocontrol strain Streptomyces pratensis S10. Although a broad spectrum of antifungal activity has been reported for VentA, little is known about its antifungal mechanisms against B. cinerea.

Results: Venturicidin A exhibited a strong hyphal inhibition of B. cinerea with an EC₅₀ (effective concentration causing 50% growth inhibition) value of 1.08 μg mL^-1 on PDA medium. Different concentrations of VentA inhibited spore germination with an inhibition rate of 49-86%. Venturicidin A also displayed protective and curative activity against the development of B. cinerea infection on tomato fruit, reducing disease incidence by ≈28-78%. Additionally, VentA effectively reduced the disease index and lesion length of gray mould on tomato plant. Meanwhile, VentA downregulated the expression levels of six genes related to pathogenicity in B. cinerea. As observed by scanning electron microscopy, B. cinerea spores and hyphae are abnormal after treatment with VentA. Propidium iodide staining revealed that VentA destroyed cell membrane integrity, causing cytoplasmic leakage. Furthermore, VentA induced accumulation of reactive oxygen species and upregulated the genes encoding subunits for NADPH oxidase in B. cinerea.

Conclusion: This study indicated that VentA displayed strong inhibitory activity against B. cinerea and effectively reduced gray mould disease. Thus, VentA has the potential to manage gray mould caused by B. cinerea. © 2024 Society of Chemical Industry.

Background: Lolium multiflorum Lam. (Italian ryegrass, annual ryegrass) is both a weed and a crop in Oregon. Because it is commonly managed using chemical controls, herbicide-resistant populations have evolved within the seed production region. A glyphosate-resistant population was identified in Yamhill County, Oregon, in a fallow field previously cropped with perennial ryegrass.

Results: Dose-response studies showed that the glyphosate-resistant population, OR12, was nine-fold more resistant to glyphosate than the susceptible population. No EPSPS amino acid substitutions known to confer glyphosate resistance were observed via gene sequencing. Quantitative polymerase chain reaction (qPCR) of genomic DNA revealed a mean 30-fold increase in EPSPS gene copies in the OR12 population. Biomass after glyphosate treatment was correlated with EPSPS gene copy number of individual plants.

Conclusion: This is the first known report of glyphosate resistance associated with EPSPS gene amplification to arise in L. multiflorum populations in Oregon. © 2024 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Background: Rednecked Peanutworm Stegasta bosqueella control is primarily achieved using broad spectrum insecticides targeting the larval stage. However, due to inconspicuous behavior and limited movement of the larvae within the peanut crop, foliar insecticides alone have been insufficient to reduce S. bosqueella populations. The poor effectiveness of chemical products, combined with the necessity of frequent fungicide applications, leads to an overuse of pesticides in peanuts. Given the challenges associated with targeting the larval stage, alternative strategies are needed to improve pest management. Our hypothesis was that by targeting the adult stage, the most mobile stage of the insect, we could decrease the levels of S. bosqueella damage in peanut crops while being less aggressive to the environment.

Results: Over 2 years, our study demonstrated that semiochemical-food-based attract and kill treatments significantly reduced the number of S. bosqueella adults captured per food-baited trap per week. This reduction was associated with fewer larvae and decreased plant damage compared to untreated control areas. To optimize this strategy, several key practices must be followed: (a) Prompt treatment application (chemical associated with attractant) should be applied upon detection of an increase in adult trap catches; (b) Timing applications to coincide with peak adult movement (6 pm to 9 pm); and (c) Applying treatments strategically on two peanut rows, 50 m apart, per hectare.

Conclusions: The attract-and-kill method can effectively reduce S. bosqueella damage in peanut crops, and has the potential to target other moth species that act as peanut defoliators. © 2024 Society of Chemical Industry.

Background: Studies have shown that Talaromyces can produce a large number of secondary metabolites in its metabolic process, many of which have good insecticidal, antibacterial, antitumor, antiviral and other biological activities. In order to explore the herbicidal activity and mechanism of Talaromyces purpureogenus CY-1, we determined the inhibitory effect of the fermentation broth of the CY-1 strain on weeds, identified the major active components, and further investigated the herbicidal mechanism.

Result: The results showed that CY-1, with IC50 values of 5.40 g/L and 4.39 g/L, respectively, exhibited good herbicidal activity against Xanthium sibiricum and Amaranthus lividus. Spraying CY-1 strain fermentation broth on redroot pigweed resulted in plant protection efficiencies and fresh weight protection efficiencies of 83.7% and 87%, respectively. The active component identified in the broth was 2-(3-hydroxybenzoyloxy) acrylic acid. Treatment of Amaranthus lividus with 2-(3-hydroxybenzoyloxy) acrylic acid resulted in trends of increasing superoxide dismutase activity, peroxidase activity, respiratory rate, cytochrome oxidase activity, and soluble protein content, followed by a decrease. Peroxidase activity, relative conductance and malondialdehyde content gradually increased, while acetyl lactate synthase and glutamine synthetase initially decreased and gradually returned to normal. The soluble sugar content showed a gradual decrease.

Conclusion: The findings of the present study indicate that 2-(3-hydroxybenzoyloxy) acrylic acid can induce oxidative stress in plants, damaging plant cell walls, weakening respiratory activity, inhibiting protein synthesis and sugar metabolism, ultimately leading to weed wilting and death. © 2024 Society of Chemical Industry.

Background: The Lim-domain binding protein PtaB, a homolog of Mfg1, governs conidiation and biofilm formation in several fungi. PtaB includes a conserved Lim-binding domain and two predicted nuclear localization sequences at its C terminus, and is co-regulated with the transcription factor Som1 downstream of the cyclic AMP-dependent protein kinase A (cAMP/PKA) pathway. However, the function of PtaB in entomopathogenic fungi remain poorly understood.

Results: Inactivation of PtaB in Metarhizium acridum resulted in delayed conidial germination, reduced conidial yield and increased sensitivities to cell wall disruptors, ultraviolet B irradiation and heat shock. In addition, the fungal virulence was significantly decreased after deletion of MaPtaB because of impairments in appressorium formation, cuticle penetration and evasion of insect immune responses in M. acridum. The MaPtaB-deletion and MaSom1-deletion strains showed similar phenotypes supporting that MaSom1/MaPtaB complex controls M. acridum normal conidiation and pathogenic progress. Upon loss of MaPtaB or MaSom1, the fungal sporulation mode in M. acridium shifted from microcycle conidiation to normal conidiation on SYA, a microcycle conidiation medium. Transcriptional analysis showed that more differentially expression genes were identified in MaSom1 RNA sequencing, and MaSom1 and MaPtaB may regulate the expression of genes for conidiation, nutrient metabolism and the cell cycle to control conidiation pattern shift.

Conclusion: These data corroborate a complex control function for MaPtaB as an important central factor interacting with MaSom1 in the cAMP/PKA pathway, which links stress tolerance, conidiation and virulence in the entomopathogenic fungus M. acridum. © 2024 Society of Chemical Industry.

Background: Females of Aedes aegypti transmit emerging arboviruses including Zika, dengue, yellow fever, and chikungunya. Control of these adult mosquitoes heavily relies on synthetic insecticides, including pyrethroids. However, insecticide resistance development in populations poses a significant challenge to vector control, particularly from knockdown resistance (kdr) mutations in the voltage-gated sodium channel (VGSC), the target of pyrethroids. This study investigated the field efficacy of Permanone, a pyrethroid-based insecticide, against Ae. aegypti by assessing the impact of three common kdr mutations (V410L, V1016I, F1534C) on mosquito survival under a real operational mosquito control scenario, by quantifying the pesticide delivered in the field.

Results: Field cage tests (FCTs) were conducted while conducting a realistic mosquito control application. Female mosquitoes from six operational areas from Harris County, TX, USA were exposed to Permanone delivered with a handheld sprayer. Permanone deposited near the cages was estimated from aluminum boats placed in the field during FCTs using gas chromatography-mass spectrometry (GC-MS). Mortality rates were recorded, and individual mosquitoes were genotyped for kdr mutations. A probit regression model was used to analyze the factors influencing mosquito survivorship. As the distance from the application source route increased, the amount of Permanone deposited decreased, resulting in higher survivorship frequency of Ae. aegypti females with the triple-resistant kdr genotype (LL/II/CC). The L allele at the 410-site significantly contributed to an increased resistance level when co-occurring with other kdr mutations.

Conclusion: This study linked the survival probabilities of mosquitoes with different kdr genotypes, and the amount of pesticide they received in the field. Pesticide quantification, control efficacy results and genotyping allowed us to empirically determine the impact of genotypic resistance on vector control in the field. © 2024 Society of Chemical Industry.