Pest Management Science最新文献

Background: Voltage-dependent anion-selective channels (VDACs) serve as pore proteins within the mitochondrial membrane, aiding in the regulation of cell life and cell death. Although the occurrence of cell death is crucial for defense against virus infection, the function played by VDAC in Bombyx mori, in response to the influence of Bombyx mori nucleopolyhedrovirus (BmNPV), remains unclear.

Results: BmVDAC was found to be relatively highly expressed both during embryonic development, and in the Malpighian tubule and midgut. Additionally, the expression levels of BmVDAC were found to be different among silkworm strains with varying levels of resistance to BmNPV, strongly suggesting a connection between BmVDAC and virus infection. To gain further insight into the function of BmVDAC in BmNPV, we employed RNA interference (RNAi) to silence and overexpress it by pIZT/V5-His-mCherry. The results revealed that BmVDAC is instrumental in developing the resistance of host cells to BmNPV infection in BmN cell-line cells, which was further validated as likely to be associated with initiating programmed cell death (PCD). Furthermore, we evaluated the function of BmVDAC in another insect, Spodoptera exigua. Knockdown of the BmVDAC homolog in S. exigua, SeVDAC, made the larvae more sensitive to BmNPV.

Conclusion: We have substantiated the pivotal role of BmVDAC in conferring resistance against BmNPV infection, primarily associated with the initiation of PCD. The findings of this study shine new light on the molecular mechanisms governing the silkworm's response to BmNPV infection, thereby supporting innovative approaches for pest biocontrol. © 2024 Society of Chemical Industry.

Backgrounds: Pesticides have been widely applied to promote plant growth due to their high insecticidal efficiency. However, most pesticides easily slip from the leaf surface due to the low foliar adhesion, leading to significant damage to the environment and human health. Increasing foliar adhesion of pesticides has been a major challenge. Nanomaterial technology, which can deliver pesticide active ingredients, offers a new opportunity to increase pesticides efficacy with higher foliar adhesion.

Results: In this study, we prepared the pesticide loaded nanohydrogel ALP@Ge-g-P(AA-co-AM)/ATP by grafting attapulgite and gelatin onto P(AA-co-AM), and loading the pesticide alphacypermethrin synchronously via the emulsion solvent evaporation method. The size of the new nanohydrogel was 20.5 nm and the pesticide loading capacity was 21.5%. Compared to P(AA-co-AM), the water absorbency of Ge-g-P(AA-co-AM)/ATP increased by 54.3% in 120 min, while the water retention increased from 4.27% to 38.7% after 48 h. Washout experiments and contact angle results suggested that the nanohydrogel, with a contact angle of 44.8° indicating good wettability, can resist rain flush and increase foliar adhesion naturally.

Conclusions: Overall, the preparation of pesticide loaded nanohydrogel is simple. Experiments demonstrated the pesticide loaded nanohydrogel has high efficiency and strong foliar adhesion. This makes it a promising candidate for spraying application and reducing pollution levels. © 2024 Society of Chemical Industry.

Background: As a type of biological control agent (BCA), Bacillus velezensis possesses the efficacy of inhibiting pathogenic microorganisms, promoting plant growth, and overcoming continuous cropping obstacles (CCOs). However, there is limited reporting on the optimization of the cultivation conditions for such biocontrol agents and their role as double-stranded RNA (dsRNA) delivery vectors.

Results: In this study, a Bacillus velezensis strain HS-3 was isolated from the root zone of tomato plants with in vitro anti-Botrytis cinerea activity. The investigation into active compounds revealed that HS-3 predominantly employs proteins with molecular weights greater than 3 kDa for its antifungal activity. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis identified various proteases and chitosanase, further suggesting that HS-3 most likely employs these enzymes to degrade fungal cell walls for its antifungal effect. To optimize the production of extracellular proteins, fermentation parameters for HS-3 were systematically optimized, leading to an optimized medium (OP-M). HS-3 cultured in OP-M demonstrated enhanced capacity to assist tomato plants in withstanding CCOs. However, the presence of excessive nematodes in diseased soil resulted in the disease severity index (DSI) remaining high. An RNA interference mechanism was further introduced to HS-3, targeting the nematode tyrosine phosphatase (TP) gene. Ultimately, HS-3 expressing dsRNA of TP in OP-M effectively assisted tomatoes in mitigating CCOs, reducing DSI to 2.2% and 17.8% of the control after 45 and 90 days of growth, respectively.

Conclusion: The advantages of Bacillus velezensis in crop disease management and the mitigation of CCOs become even more pronounced when utilizing both optimized levels of endogenous enzymes and introduced nematode-targeting dsRNA. © 2024 Society of Chemical Industry.

Background: Grapevine downy mildew, caused by Plasmopara viticola, is an economically important disease in Australia and worldwide. The application of fungicides is the main tool to control this disease. Frequent fungicide applications can lead to the selection of resistant P. viticola populations, which has negative impacts on the management of the disease. Identification of resistance and its prevalence is necessary to inform resistance management strategies.

Results: A total of 86 P. viticola isolates were collected between 2017 and 2022 from vineyards in 15 growing regions across Australia for four fungicide groups; phenylamide (PA, group 4), carboxylic acid amide (CAA, group 40), quinone outside inhibitor (QoI, group 11) and quinone outside inhibitor stigmatellin binding type (QoSI, group 45). Decreased phenotypic sensitivity was detected for all four groups, and resistance to metalaxyl-M (PA) and pyraclostrobin (QoI), was detected. Genetic analysis to detect the G143A (QoI) and G1105S (CAA) mutations using amplicon-based sequencing was performed for 239 and 65 isolates collected in 2014-2017 and 2017-2022, respectively. G143A was detected in 8% and 52% of isolates, respectively, with strong association to phenotypic resistance. However, G1105S was not detected in any isolates.

Conclusion: Plasmopara viticola isolates in Australia with resistance to at least two fungicide groups have been detected, therefore it is necessary to adopt resistance management strategies where resistance has been detected. Vineyards should continue to be monitored to improve management strategies for downy mildew. © 2024 Society of Chemical Industry.

Background: Sclerotium rolfsii is a destructive soil-borne fungal pathogen which is distributed worldwide. In previous study, the succinate dehydrogenase inhibitor (SDHI) fungicide benzovindiflupyr has been identified for its great antifungal activity against Sclerotium rolfsii. This study is aimed to investigate the resistance risk and mechanism of benzovindiflupyr in Sclerotium rolfsii.

Results: Eight stable benzovindiflupyr-resistant isolates were generated by fungicide adaptation. Although the obtained eight resistant isolates have a stronger pathogenicity than the parental sensitive isolate, they have a fitness penalty in the mycelial growth and sclerotia formation compared to the parental isolate. A positive cross-resistance existed in the resistant isolates between benzovindiflupyr and thifluzamide, carboxin, boscalid and isopyrazam. Three-point mutations, including SdhB^N180D, SdhC^Q68E and SdhD^H103Y, were identified in the benzovindiflupyr-resistant isolates. However, molecular docking analysis indicated that only SdhD^H103Y could influence the sensitivity of Sclerotium rolfsii to benzovindiflupyr. After mycelial co-incubation of resistant isolates and the sensitive isolate, resistance genes may be transmitted to the sensitive isolate. The in vivo efficacy of benzovindiflupyr and thifluzamide against benzovindiflupyr-resistant isolates was a little lower than that against the sensitive isolate but with no significant difference.

Conclusion: The results suggested a low to medium resistance risk of Sclerotium rolfsii to benzovindiflupyr. However, once resistance occurs, it is possible to spread in the population of Sclerotium rolfsii. This study is helpful to understanding the risk and mechanism of resistance to benzovindiflupyr in multinucleate pathogens such as Sclerotium rolfsii. © 2024 Society of Chemical Industry.

Background: To further develop potential natural fungicides, two series of new acrylopimaric acid triazole derivatives were synthesized, and their antifungal activities were tested and evaluated.

Results: In vitro antifungal activity results indicated that compound 5m exhibited significant inhibitory activity against Rhizoctonia solani with an half maximal effective concentration (EC₅₀) value of 1.528 mg/L. Its antifungal effect was comparable to that of the commercially available fungicide fluconazole, epoxiconazole and propiconazole (EC₅₀ values of 1.441, 0.815 and 1.173 mg/L). Subsequently, in vivo studies were conducted on compound 5m, which revealed its significant protective and curative effects against R. solani. In addition, physiological and biochemical studies showed that compound 5m could disrupt the morphology and ultrastructure of R. solani mycelium, increase cell membrane permeability, inhibit ergosterol synthesis, and enhance the activity of defense enzymes in rice plants. Three-dimensional quantitative structure-activity relationship (3D-QSAR) studies revealed that the molecular structure significantly influenced the binding of compound 5m to the receptor, thereby enhancing its antifungal activity.

Conclusion: Compound 5m exhibits excellent antifungal activity against R. solani, making it a promising candidate fungicide for the prevention and control of R. solani. © 2024 Society of Chemical Industry.

Background: Toxins of Bacillus thuringiensis subsp. israelensis (Bti) are safer alternatives for controlling dipteran pests such as black flies and mosquitoes. The biting midge Culicoides sonorensis (Diptera: Ceratopogonidae) is an important pest of livestock in much of the United States and larval midges utilize semi-aquatic habitats which are permissive for Bti product application. Reports suggest that Bti products are ineffective at killing biting midges despite their taxonomic relation to black flies and mosquitoes. Here, we investigate the toxicity of a Bti-based commercial insecticide and its active ingredient in larval Culicoides sonorensis. A suspected mechanism of Bti tolerance is an acidic larval gut, and we used a pH indicator dye to examine larval Culicoides sonorensis gut pH after exposure to Bti.

Results: The lethal concentration to kill 90% (LC₉₀) of larvae of the commercial product (386 mg/L) was determined to be almost 10 000 times more than that of some mosquito species, and no concentration of active ingredient tested achieved 50% larval mortality. The larval gut was found to be more acidic after exposure to Bti which inhibits Bti toxin activity. By comparison, 100% mortality was achieved in larval Aedes aegypti at the product's label rate for this species and mosquito larvae had alkaline guts regardless of treatment. Altering the larval rearing water to alkaline conditions enhanced Bti efficacy when using the active ingredient.

Conclusion: We conclude that Bti is not practical for larval Culicoides sonorensis control at the same rates as mosquitos but show that alterations or additives to the environment could make the products more effective. © 2024 Society of Chemical Industry.

Objective: In India, agriculture is the backbone of economic sectors because of the increasing demand for agricultural products. However, agricultural production has been affected due to the presence of pests in crops. Several methods were developed to solve the crop pest detection issue, but they failed to achieve better results. Therefore, the proposed study used a new hybrid deep learning mechanism for segmenting and detecting pests in crops.

Method: Image collection, pre-processing, segmentation, and detection are the steps involved in the proposed study. There are three steps involved in pre-processing: image rescaling, equalized joint histogram based contrast enhancement (Eq-JH-CE), and bendlet transform based De-noising (BT-D). Next, the pre-processed images are segmented using the DenseNet-77 UNet model. In this section, the complexity of the conventional UNet model is mitigated by hybridizing it with the DenseNet-77 model. Once the segmentation is done with an improved model, the crop pests are detected and classified by proposing a novel Convolutional Slice-Attention based Gated Recurrent Unit (CS-AGRU) model. The proposed model is the combination of a convolutional Neural Network (CNN) and a Gated Recurrent Unit (GRU). In order to achieve better accuracy outcomes, the proposed study hybridized these models due to their great efficiency. Also, the slice attention mechanism is applied over the proposed model for fetching relevant feature information and thereby enhancing the computational efficiency. So, pests in the crop are finally detected using the proposed method.

Result: The Python programming language is utilized for implementation. The proposed approach shows a better accuracy range of 99.52%, IoU of 99.1%, precision of 98.88%, recall of 99.53%, F1-score of 99.35%, and FNR of 0.011 compared to existing techniques.

Discussion: Identifying and classifying pests helps farmers anticipate potential threats to their crops. By knowing which pests are prevalent in their region or are likely to infest certain crops, farmers can implement preventive measures to protect their crops, such as planting pest-resistant varieties, using crop rotation, or deploying traps and barriers. © 2024 Society of Chemical Industry.

Background: Reproductive diapause serves as a valuable strategy enabling insects to survive unfavorable seasonal conditions. However, forcing insects into diapause when the environment is conducive to their well-being can cause them to miss out on seasonal opportunities for reproduction. This outcome not only reduces insect populations but also minimizes crop losses caused by insect feeding. Therefore, altering the timing of diapause initiation presents a potential strategy for managing pests. In this study, we examined the possible role of the Insulin Receptor 1 (InR1) in controlling reproductive diapause entry in the male cabbage beetle, Colaphellus bowringi.

Results: Compared to short-day (SD) conditions, long-day (LD) conditions led to reproductive diapause of C. bowringi males, characterized by arrested gonad development, increased Triglyceride (TG) accumulation, and upregulated expression of diapause protein 1 and genes associated with lipogenesis and stress tolerance. Upon employing RNA interference to knock down InR1 under SD conditions, males destined for reproduction were compelled into diapause, evidenced by arrested gonadal development, accumulation of TG, and elevated expression of diapause-related genes. Intriguingly, despite the common association of the absence of juvenile hormone (JH) with reproductive diapause in females, the knockdown of InR1 in males did not significant affect the expression of JH biosynthesis and JH response gene.

Conclusion: The study highlight InR1 is a key factor involved in regulating male reproductive diapause in C. bowringi. Consequently, targeting insulin signaling could be a viable approach to perturb diapause timing, offering a promising strategy for managing pests with reproductive diapause capabilities. © 2024 Society of Chemical Industry.

Background: Citrus huanglongbing (HLB) is a devastating disease caused by Candidatus Liberibacter asiaticus (CLas) that affects the citrus industry. In nature, CLas relies primarily on Diaphorina citri Kuwayama as its vector for dissemination. After D. citri ingests CLas-infected citrus, the pathogen infiltrates the insect's body, where it thrives, reproduces, and exerts regulatory control over the growth and metabolism of D. citri. Previous studies have shown that CLas alters the composition of proteins in the saliva of D. citri, but the functions of these proteins remain largely unknown.

Results: In this study, we detected two proteins (DcitSGP1 and DcitSGP3) with high expression levels in CLas-infected D. citri. Quantitative PCR and Western blotting analysis showed that the two proteins were highly expressed in the salivary glands and delivered into the host plant during feeding. Silencing the two genes significantly decreased the survival rate for D. citri, reduced phloem nutrition sucking and promoted jasmonic acid (JA) defenses in citrus. By contrast, after overexpressing the two genes in citrus, the expression levels of JA pathway-associated genes decreased.

Conclusion: Our results suggest that CLas can indirectly suppress the defenses of citrus and support feeding by D. citri via increasing the levels of effectors in the insect's saliva. This discovery facilitates further research into the interaction between insect vectors and pathogens. © 2024 Society of Chemical Industry.