Knockdown of double-stranded RNases (dsRNases) enhances oral RNA interference (RNAi) in the corn leafhopper, Dalbulus maidis.

The leafhopper Dalbulus maidis is a harmful pest that causes severe damage to corn crops. Conventional chemical pesticides have negative environmental impacts, emphasizing the need for alternative solutions. RNA interference (RNAi) is a more specific and environmentally friendly method for controlling pests and reducing the negative impacts of current pest management practices. Previous studies have shown that orally administered double-stranded RNA (dsRNA) is less effective than injection protocols in silencing genes. This study focuses on identifying and understanding the role of double-stranded ribonucleases (dsRNases) in limiting the efficiency of oral RNAi in D. maidis. Three dsRNases were identified and characterized, with Dmai-dsRNase-2 being highly expressed in the midgut and salivary glands. An ex vivo degradation assay revealed significant nuclease activity, resulting in high instability of dsRNA when exposed to tissue homogenates. Silencing Dmai-dsRNase-2 improved the insects' response to the dsRNA targeting the gene of interest, providing evidence of dsRNases involvement in oral RNAi efficiency. Therefore, administering both dsRNase-specific and target gene-specific-dsRNAs simultaneously is a promising approach to increase the efficiency of oral RNAi and should be considered in future control strategies.

Modulating tumor reactive stroma by extracorporeal shock waves to control prostate cancer progression.

BACKGROUND: Prostate cancer is the second most common cancer worldwide. Tumor microenvironment is composed of activated fibroblasts, the so called carcinoma-associated fibroblasts (CAFs). They express high levels of α-smooth muscle actin (α-SMA) and type I collagen (COL1), and support proliferation and migration of tumor epithelial cells. Extracorporeal shock waves (ESWs), acoustic waves, are effective in the treatment of hypertrophic scars, due to their ability to modulate fibrosis. Based on this rationale, the study evaluated the effects of ESWs on CAF activation and the influence of ESW-treated CAFs on the growth and migration of epithelial prostatic carcinoma cells. METHODS: Primary cultures of CAFs (n = 10) were prepared from tumors of patients undergoing surgery for high-risk prostate carcinoma. CAFs were treated with ESWs (energy levels: 0.32 mJ/mm2 , 1000 pulses; 0.59 mJ/mm2 , 250 pulses). After treatment, the messenger RNA and protein levels of the stromal activation markers α-SMA and COL1 were determined. Subsequently, two different stabilized cell lines (PC3 and DU145) of androgen-resistant prostate cancer were treated with the conditioned media produced by ESW-treated CAFs. At different times, viability and migration of PC3 and DU145 cells were evaluated. Viability was also assessed by coculture system using CAFs and PC3 or DU145 cells. RESULTS: ESWs reduced gene expression and protein level of α-SMA and COL1 in CAFs. The treatment of PC3 and DU145 with conditioned media of ESW-treated CAFs determined a reduction of their growth and invasive potential. Coculture systems between ESW-treated CAFs and PC3 or DU145 cells confirmed the epithelial cell number reduction. CONCLUSIONS: This in vitro study demonstrates for the first time that ESWs are able to modulate the activation of prostate CAFs in favor of a less "reactive" stroma, with consequent slowing of the growth and migration of prostate cancer epithelial cells. However, only further studies to be performed in vivo will confirm the possibility of using this new therapy in patients with prostate cancer.

Antidepressant Augmentation: A Review of the Literature and a Review of the Pharmacoeconomic Considerations.

PURPOSE: Antidepressant augmentation strategies for treatment-resistant depression (TRD) are discussed here with an analysis of patient out-of-pocket costs for various medications. The choice of agent ranges from newer atypical antipsychotics (aripiprazole, brexpiprazole, quetiapine) to older agents including buspirone, liothyronine (T3), and lithium. We sought to better understand the differences among these agents to aid in clinical decision making. METHODS: We conducted a focused review of the support for each of the aforementioned agents in antidepressant augmentation. We then compared the approximate out-of-pocket cost for each medication during a typical augmentation trial using the typical prescription costs on ClinCalc.com derived from the Medical Expenditure Panel Survey. We calculated the cost to achieve response for one patient with TRD based on the number needed to treat (NNT). FINDINGS: We observed significant variance in cost to achieve response based on the NNT derived from our review of each of the medications. For example, the overall out-of-pocket cost for one patient to achieve response with aripiprazole (the costliest generic agent) could cover lithium prescriptions for 4 to 5 patients with TRD to achieve response. Although brexpiprazole was estimated separately because of its brand name cost, we estimated that 324 patients receiving lithium could achieve response for same cost of single patient receiving brexpiprazole. IMPLICATIONS: These findings suggest that among augmentation agents, there are differences in cost that may be highly important in clinical decision making. Other issues of medication monitoring may incur additional costs, and brand name medications offer significantly greater complexity and potential out-of-pocket costs to patients. The use of lithium as a first-line agent for TRD should be considered based on low cost, lowest NNT, and data in support of its efficacy.

Benzene affects the response to octreotide treatment of growth hormone secreting pituitary adenoma cells.

Growth hormone (GH) secreting pituitary adenomas are the main cause of acromegaly. Somatostatin analogs are the gold standard of medical therapy; however, resistance represents a big drawback in acromegaly management. We recently demonstrated that benzene (BZ) modifies the aggressiveness of GH-secreting rat pituitary adenoma cells (GH3), increasing GH secretion and altering the synthesis of molecules involved in the somatostatin signaling pathway. Based on these pieces of evidence, this study aimed to evaluate the effects of BZ on octreotide (OCT) efficacy in GH-secreting adenoma cells. In GH3 cells, BZ counteracted the anti-proliferative action of OCT. GH gene expression, unmodified by OCT, remained high in BZ-treated cells as well as after treatment with the association of both. GH secretion, reduced by OCT, was increased after treatment with BZ alone or when the pollutant was used with OCT. The combination of BZ and OCT greatly reduced the gene expression of ZAC1 and SSTR2; and this reduction was also present at a protein level. BZ caused an increase in the protein level of the transcription factor STAT3 and in its phosphorylated form. In the presence of BZ, OCT lost the ability to reduce the phosphorylated protein levels. Finally, in primary cultures of human pituitary adenoma cells, BZ caused an increase in GH secretion. OCT decreased GH secretion, but the addition of BZ reversed the OCT effect. In conclusion, our results suggest that BZ may have an important role in the resistance of pituitary adenomas to the pharmacological treatment with somatostatin analogs.

FOXA1 and AR in invasive breast cancer: new findings on their co-expression and impact on prognosis in ER-positive patients.

BACKGROUND: The role of forkhead-box A1 (FOXA1) and Androgen receptor (AR) in breast cancer (BC) has been extensively studied. However, the prognostic role of their co-expression in Estrogen receptor positive (ER+) BC has not been investigated so far. The aim of the present study was thus to assess the co-expression (protein and mRNA) of FOXA1 and AR in BC patients, in order to evaluate their prognostic impact according to ER status. METHODS: Immunohistochemical expression of AR and FOXA1 was evaluated on 479 consecutive BC, with complete clinical-pathological and follow up data. Fresh-frozen tissues from 65 cases were available. The expression of AR and FOXA1 with ER was validated using mRNA analyses. Survival and Cox proportional hazard analyses were used to evaluate the relationship between FOXA1, AR and prognosis. RESULTS: Expression of ER, AR and FOXA1 was observed in 78, 60 and 85% of cases respectively. Most AR+ cases (97%) were also FOXA1+. The level of FOXA1 mRNA positively correlated with level of both AR mRNA (r = 0.8975; P < 0.001) and ER mRNA (r = 0.7326; P < 0.001). In ER+ BC, FOXA1 was associated with a good prognosis independently of AR expression in the three subgroups analyzed (FOXA1+/AR+; FOXA1+/AR-; FOXA1-/AR-). Multivariate analyses confirmed that FOXA1 may provide more information than AR in Disease-Free Interval (DFI) of ER+ BC patients. CONCLUSION: Our results suggest that in BC the expression of FOXA1 is directly related to the expression of AR. Despite that, FOXA1 is found as superior predicting marker of recurrences compared to AR in ER+ BC patients.

Extracorporeal shock waves trigger tenogenic differentiation of human adipose-derived stem cells.

PURPOSES: Incomplete tendon healing impairs the outcome of tendon ruptures and tendinopathies. Human Adipose-derived Stem Cells (hASCs) are promising for tissue engineering applications. Extracorporeal Shock Waves (ESW) are a leading choice for the treatment of several tendinopathies. In this study, we investigated the effects of ESW treatment and tenogenic medium on the differentiation of hASCs into tenoblast-like cells. MATERIALS AND METHODS: hASCs were treated with ESW generated by a piezoelectric device and tenogenic medium. Quantitative real-time PCR was used to check the mRNA expression levels of tenogenic transcription factors, extracellular matrix proteins, and integrins. Western blot and immunofluorescence were used to detect collagen 1 and fibronectin. Collagen fibers were evaluated by Masson staining. Calcium deposition was assessed by Alizarin Red staining. RESULTS: The combined treatment improved the expression of the tendon transcription factors scleraxis and eyes absent 2, and of the extracellular matrix proteins fibronectin, collagen I, and tenomodulin. Cells acquired elongated and spindle shaped fibroblastic morphology; Masson staining revealed the appearance of collagen fibers. Finally, the combined treatment induced the expression of alpha 2, alpha 6, and beta 1 integrin subunits, suggesting a possible role in mediating ESW effects. CONCLUSIONS: ESW in combination with tenogenic medium improved the differentiation of hASCs toward tenoblast-like cells, providing the basis for ESW and hASCs to be used in tendon tissue engineering.

Novel sol-gel fabrication of Yb3+/Tm3+ co-doped ß-NaYF4 thin films and investigation of their upconversion properties.

An innovative sol-gel process, using a mixture of Na(hfa)·tetraglyme and RE(hfa)3·diglyme (RE = Y, Yb, Tm) complexes, has been optimized to produce upconverting ß-NaYF4:Yb3+/Tm3+ thin films. The X-ray diffraction (XRD) analysis confirms that the new sol-gel preparation route yields reproducibly and selectively the hexagonal Na(Y1.5Na0.5)F6 structure (ß-NaYF4) without any impurity phases, since no peaks of the cubic NaYF4, YOF, Y2O3 or NaF phases were observed. This final goal has been achieved through an accurate optimization of the operative parameters such as the molar ratio of the precursor mixture, the aging time of the sol, the spin coating procedure and the annealing temperature. Field-emission scanning electron microscopy (FE-SEM) images indicate that the morphology of the surfaces, grain dimensions and thickness are strongly related to the processing parameters, with the hexagonal phase films having a very uniform morphology. Energy dispersive X-ray (EDX) analyses established the film composition in terms of dopant ions, which are responsible for the upconverting properties of the material. Luminescence measurements under laser excitation at 980 nm confirmed the promising upconversion properties of the ß-NaYF4:Yb3+/Tm3+ films.

Motor and Perceptual Recovery in Adult Patients with Mild Intellectual Disability.

Introduction: The relationship between intellectual disability (ID) and hand motor coordination and speed-accuracy, as well as the effect of aging on fine motor performance in patients with ID, has been previously investigated. However, only a few data are available on the impact of the nonpharmacological interventions in adult patients with long-term hand motor deficit. Methods: Fifty adults with mild ID were enrolled. A group of thirty patients underwent a two-month intensive ergotherapic treatment that included hand motor rehabilitation and visual-perceptual treatment (group A); twenty patients performing conventional motor rehabilitation alone (group B) served as a control group. Data on attention, perceptual abilities, hand dexterity, and functional independence were collected by a blind operator, both at entry and at the end of the study. Results: After the interventions, group A showed significantly better performance than group B in all measures related to hand movement from both sides and to independence in activities of daily living. Discussion: Multimodal integrated interventions targeting visual-perceptual abilities and motor skills are an effective neurorehabilitative approach in adult patients with mild ID. Motor learning and memory-mediated mechanisms of neural plasticity might underlie the observed recovery, suggesting the presence of plastic adaptive changes even in the adult brain with ID.

Effects of environmental pollutants on signaling pathways in rat pituitary GH3 adenoma cells.

An increased rate of acromegaly was reported in industrialized areas, suggesting an involvement of environmental pollutants in the pathogenesis and behavior of GH-secreting pituitary adenomas. Based on these premises, the aim of the study was to evaluate the effects of some widely diffused pollutants (i.e. benzene, BZ; bis(2-ethylhexyl) phthalate, DEHP and polychlorinated biphenyls, PCB) on growth hormone secretion, the somatostatin and estrogenic pathways, viability and proliferation of rat GH-producing pituitary adenoma (GH3) cells. All the pollutants induced a statistically significant increase in GH secretion and interfered with cell signaling. They all modulated the expression of SSTR2 and ZAC1, involved in the somatostatin signaling, and the expression of the transcription factor FOXA1, involved in the estrogen receptor signaling. Moreover, all the pollutants increased the expression of the CYP1A1, suggesting AHR pathway activation. None of the pollutants impacted on cell proliferation or viability. Present data demonstrate that exposure to different pollutants, used at in vivo relevant concentrations, plays an important role in the behavior of GH3 pituitary adenoma cells, by increasing GH secretion and modulating several cellular signaling pathways. These observations support a possible influence of different pollutants in vivo on the GH-adenoma aggressiveness and biological behavior.

Benzene and 2-ethyl-phthalate induce proliferation in normal rat pituitary cells.

PURPOSE: Endocrine disruptors are known to modulate a variety of endocrine functions and increase the risk for neoplasia. Epidemiological data reported increased prevalence of pituitary tumors in high industrial areas while genotyping studies showed that mutations in the aryl hydrocarbon receptor (AhR) interacting protein (AIP)-chaperone to the dioxin ligand AhR-gene are linked to predisposition to pituitary tumor development. Aim of the present study was to establish whether endocrine pollutants can induce cell proliferation in normal rat pituitary cells. METHODS: Pituitary primary cultures were incubated with 250, 650 and 1250 pM benzene or 2-ethyl-phthalate for up to 96 h and viability, energy content and cell proliferation assessed. Expression of pituitary tumor transforming gene (PTTG), cyclin D1 (Ccnd1), AhR and AIP was quantified by RT-qPCR. RESULTS: Incubation with benzene or 2-ethyl-phthalate increased viability and energy content in pituitary cells. The endocrine disruptors also increased cell proliferation as well as Ccnd1 and PTTG expression. Increased AhR and AIP expression was observed after incubation with the two pollutants. CONCLUSIONS: Our findings indicate that benzene and 2-ethyl-phthalate activate AhR/AIP expression and stimulate proliferation in normal rat pituitary cells. This study is the first demonstration that pollutants can induce normal pituitary cells to proliferate and provides a link between epidemiological and genomic findings in pituitary tumors.

Extracorporeal shock waves modulate myofibroblast differentiation of adipose-derived stem cells.

Mesenchymal stem cells are precursors of myofibroblasts, cells deeply involved in promoting tissue repair and regeneration. However, since myofibroblast persistence is associated with the development of tissue fibrosis, the use of tools that can modulate stem cell differentiation toward myofibroblasts is central. Extracorporeal shock waves are transient short-term acoustic pulses first employed to treat urinary stones. They are a leading choice in the treatment of several orthopedic diseases and, notably, they have been reported as an effective treatment for patients with fibrotic sequels from burn scars. Based on these considerations, the aim of this study is to define the role of shock waves in modulating the differentiation of human adipose-derived stem cells toward myofibroblasts. Shock waves inhibit the development of a myofibroblast phenotype; they down-regulate the expression of the myofibroblast marker alpha smooth muscle actin and the extracellular matrix protein type I collagen. Functionally, stem cells acquire a more fibroblast-like profile characterized by a low contractility and a high migratory ability. Shock wave treatment reduces the expression of integrin alpha 11, a major collagen receptor in fibroblastic cells, involved in myofibroblast differentiation. Mechanistically, the resistance of integrin alpha 11-overexpressing cells to shock waves in terms of alpha smooth muscle actin expression and cell migration and contraction suggests also a role of this integrin in the translation of shock wave signal into stem cell responses. In conclusion, this in vitro study shows that stem cell differentiation toward myofibroblasts can be controlled by shock waves and, consequently, sustains their use as a therapeutic approach in reducing the risk of skin and tissue fibrosis.

Review of the genera Paulomanus Young, 1952 and Beamerana Young, 1952 (Hemiptera: Cicadellidae: Typhlocybinae: Empoascini) with description of a new species from Argentina.

The Neotropical microleafhopper genera Paulomanus and Beamerana are redescribed based on study of type material and newly collected specimens. Paulomanus is recorded for the first time from Argentina and a new species, P. falciformis n. sp., is described. Detailed morphological description and illustration of the new species and a key to males of the known species of Paulomanus are provided. A key to genera of the New World Empoascini is also provided.

Clinical characteristics, treatment, trajectories and outcome of patients with dilated cardiomyopathy in a national heart failure registry.

BACKGROUND: Available data on the clinical characteristics and prognosis of patients with heart failure (HF) due to dilated cardiomyopathy (DCM) derive mainly from tertiary care centres for cardiomyopathies or from drug trial sub-studies, which may entail a referral bias. METHODS: From 2008 to 2021, we enrolled in a nationwide HF Registry 1886 DCM patients and 3899 with ischemic heart disease (IHD). RESULTS: Patients with DCM were younger, more often female, had more commonly recent onset HF, left bundle branch block, and showed higher LV end-diastolic volume and lower LVEF than IHD. With respect to IHD, DCM patients received more often mineralocorticoid receptor antagonists, renin angiotensin system inhibitors and betablockers, the latter more commonly at doses ≥50% of target, and triple guideline-directed medical therapy (GDMT) (adjusted OR 1.411, 95% CI 1.247-1.595, p < .0001). During one-year follow-up, 819 patients (14.2%) died or were hospitalized for HF [187 (9.9%) DCM, 632 (16.2%) IHD]; DCM was associated with lower risk of the combined end-point (adjusted HR 0.745, 95% CI 0.625- 0.888, p = .0011). Among the 1954 patients with 1-year echocardiograms available, 1483 had LVEF≤40% at baseline; of these,166 (30.6%) DCM and 165 (17.5%) IHD improved their LVEF to >40% (p < .0001). DCM aetiology was associated with higher likelihood of LVEF improvement (adjusted OR 1.722, 95% CI 1.328 -2.233, p < .0001). CONCLUSIONS: DCM patients have a different clinical profile, greater uptake of GDMT and better outcomes than IHD subjects. A comprehensive management approach is needed to further address the risk of unfavorable outcomes in DCM.

Dickkopf-1 (DKK1) drives growth and metastases in castration-resistant prostate cancer.

Metastatic castration-resistant prostate cancer (mCRPC) is associated with a poor prognosis and remains an incurable fatal disease. Therefore, the identification of molecular markers involved in cancer progression is urgently needed to develop more-effective therapies. The present study investigated the role of the Wnt signaling modulator Dickkopf-1 (DKK1) in the growth and metastatic progression of mCRPC. DKK1 silencing through siRNA and deletion via CRISPR/Cas9 editing were performed in two different metastatic castration-resistant prostate cancer cell lines (PC3 and DU145). A xenograft tumor model was used to assess tumor growth and metastases. In in vitro experiments, both DKK1 silencing and deletion reduced cell growth and migration of both cell lines. DKK1 knockout clones (DKK1-KO) exhibited cell cycle arrest, tubulin reorganization, and modulation of tumor metastasis-associated genes. Furthermore, in DKK1-KO cells, E-cadherin re-expression and its membrane co-localization with ß-catenin were observed, contributing to reduced migration; Cadherin-11, known to increase during epithelial-mesenchymal transition, was down-regulated in DKK1-KO cells. In the xenograft mouse model, DKK1 deletion not only reduced tumor growth but also inhibited the formation of lung metastases. In conclusion, our findings support the key role of DKK1 in the growth and metastatic dissemination of mCRPC, both in vitro and in vivo.

Three new species of Neozygina Dietrich & Dmitriev (Hemiptera, Cicadellidae, Typhlocybinae) from Argentina, with a key to South American species.

Three new species of Neozygina Dietrich & Dmitriev are described from Argentina, N. apicalis sp. nov., N. bifurcata sp. nov. and N. spinula sp. nov. Detailed morphological descriptions and illustrations of the new species are provided, and a key to South American species of the genus is given.

Four new species of genus Parallaxis McAtee (Hemiptera: Cicadellidae: Typhlocybinae: Dikraneurini) from Argentina, with a key to known species.

Four new species of Parallaxis McAtee are described from Argentina, P. jujuiensis sp. n., P. misionensis sp. n., P. tucumanensis sp. n. and P. virlai sp. n. Detailed morphological descriptions and illustrations of the new species and a key to males of known species are provided.

Cytotoxic activity of the histone deacetylase inhibitor panobinostat (LBH589) in anaplastic thyroid cancer in vitro and in vivo.

Anaplastic thyroid carcinoma (ATC) has a rapidly fatal clinical course, being resistant to multimodal treatments. Microtubules, α/ß tubulin heterodimers, are crucial in cell signaling, division and mitosis and are among the most successful targets for anticancer therapy. Panobinostat (LBH589) is a potent deacetylase inhibitor acting both on histones and nonhistonic proteins, including α-tubulin. In vitro LBH589, evaluated in three ATC cell lines (BHT-101, CAL-62 and 8305C), resulted in impairment of cell viability, inhibition of colony formation, cell cycle arrest and apoptosis induction. Mechanistically, we showed that LBH589 not only affected the expression of p21 and cyclin D1, but markedly determined microtubule stabilization as evidenced by tubulin acetylation and increased tubulin polymerization. In a SCID xenograft model implanted with CAL-62 cells, the cytotoxic properties of LBH589 were confirmed. The drug at the dose of 20 mg/kg significantly impaired tumor growth (final tumor volume 2.5-fold smaller than in untreated animals); at this dose, no relevant side effects were observed. In tumors of treated animals, a significant reduction of Ki67, which was negatively correlated with tubulin acetylation, was observed. Moreover, acetyl-tubulin levels negatively correlated with tumor volume at sacrifice, reinforcing the opinion that tubulin acetylation has a role in the inhibition of tumor growth. In conclusion, LBH589, acting on both histones and nonhistonic proteins in anaplastic thyroid cancer, appears to be a promising therapeutic agent for the treatment of this kind of cancer which is known not to respond to conventional therapy.

Effect of n-3 fatty acids on patients with advanced lung cancer: a double-blind, placebo-controlled study.

PUFA from fish oil appear to have anti-inflammatory and anti-oxidative effects and improve nutritional status in cancer patients. With this as background, the aim of the present study was to investigate the effect of EPA plus DHA on inflammatory condition, and oxidative and nutritional status in patients with lung cancer. In our multicentre, randomised, double-blind trial, thirty-three patients with a diagnosis of advanced inoperable non-small-cell lung cancer and undergoing chemotherapy were divided into two groups, receiving four capsules/d containing 510 mg of EPA and 340 mg of DHA, or 850 mg of placebo, for 66 d. At the start of chemotherapy (T0), after 8 d (T1), 22 d (T2) and 66 d (T3), biochemical (inflammatory and oxidative status parameters) and anthropometric parameters were measured in both groups. A significant increase of body weight in the n-3 group at T3 v. T0 was observed. Concerning inflammation, C-reactive protein and IL-6 levels differed significantly between the n-3 and placebo groups at T3, and progressively decreased during chemotherapy in the n-3 group, evidencing n-3 PUFA anti-inflammatory action. Concerning oxidative status, plasma reactive oxygen species levels increased in the placebo group v. the n-3 group at the later treatment times. Hydroxynonenal levels increased in the placebo group during the study, while they stabilised in the n-3 group. Our data confirm that the continual assumption of EPA plus DHA determined an anti-inflammatory and anti-oxidative action which could be considered a preliminary goal in anti-cachectic therapy.

Probing behavior of the corn leafhopper Dalbulus maidis on susceptible and resistant maize hybrids.

The corn leafhopper Dalbulus maidis is the main vector of the pathogens that cause corn stunt, a major disease of maize in the Americas. In line with plant resistance being an efficient tool to control diseases, the findings of a previous work showed that some corn hybrids are resistant to D. maidis. In this work, we assessed the probing behavior of D. maidis on susceptible and resistant corn hybrids using EPG (Electrical Penetration Graph) technology. Feeding of fifteen-day-old, non-inoculative females was recorded for 20 hours, with access to hybrids DK390, DK670, DK79-10, and DK72-10. Compared to the susceptible hybrid DK670, the other hybrids shifted D. maidis probing behavior in a way consistent with plant resistance to insects. This shift consisted of a higher number of probes of short duration, difficulties in attaining phloem ingestion and increase in xylem ingestion. In addition to this common shift in probing behavior, a phloem-located resistance factor was inferred in DK72-10 based on the longer time spent in phloem conditioning to attain phloem ingestion. In contrast, DK390 expressed the highest level of mesophyll and phloem-based resistance, in both cases seen with repeated attempts of short duration, a behavior typically associated with failed attempts to ingest. These findings support and are consistent with previous research, providing useful information to characterize maize hybrids resistant to D. maidis, and consequently to corn stunt.

Development of efficient RNAi methods in the corn leafhopper Dalbulus maidis, a promising application for pest control.

BACKGROUND: The corn leafhopper Dalbulus maidis is the main vector of important stunting pathogens that affect maize production. Currently, there are no effective methods available to manage this pest without adverse impact on the environment. In this context, genomic-based technologies such as RNA interference (RNAi) provide a more environmentally friendly pest control strategy. Therefore, we aimed to assess the application of RNAi in D. maidis and determine the function of a candidate gene related to insect reproduction and propagation. RESULTS: We have characterized the core RNAi genes and evaluated the functionality of the RNAi machinery. We assessed the potential of RNAi technology in D. maidis via injection or ingestion of double-stranded RNA (dsRNA) to adult females. We chose Bicaudal C (BicC) as a target gene due to its important role during insect oogenesis. Administration of dsRNABicC caused significant reductions in the transcript levels (fold changes up to 170 times) and ovipositions. Phenotypic analysis of the ovaries revealed alterations in oocyte development, providing additional confirmation for our results and supporting the idea that Dmai-BicC is a key player of D. maidis oogenesis. CONCLUSION: This is, to our knowledge, the first report of efficient RNAi in D. maidis. We believe our findings provide a starting point for future control strategies against one of the most important maize pests in the Americas. © 2022 Society of Chemical Industry.