Genetic diversity of RNA viruses infecting invertebrate pests of rice.

Invertebrate species are a natural reservoir of viral genetic diversity, and invertebrate pests are widely distributed in crop fields. However, information on viruses infecting invertebrate pests of crops is limited. In this report, we describe the deep metatranscriptomic sequencing of 88 invertebrate samples covering all major invertebrate pests in rice fields. We identified 296 new RNA viruses and 13 known RNA viruses. These viruses clustered within 31 families, with many highly divergent viruses constituting potentially new families and genera. Of the identified viruses, 13 RNA viruses clustered within the Fiersviridae family of bacteriophages, and 48 RNA viruses clustered within families and genera of mycoviruses. We detected known rice viruses in novel invertebrate hosts at high abundances. Furthermore, some novel RNA viruses have genome structures closely matching to known plant viruses and clustered within genera of several plant virus species. Forty-five potential insect pathogenic RNA viruses were detected in invertebrate species. Our analysis revealed that host taxonomy plays a major role and geographical location plays an important role in structuring viral diversity. Cross-species transmission of RNA viruses was detected between invertebrate hosts. Newly identified viral genomes showed extensive variation for invertebrate viral families or genera. Together, the large-scale metatranscriptomic analysis greatly expands our understanding of RNA viruses in rice invertebrate species, the results provide valuable information for developing efficient strategies to manage insect pests and virus-mediated crop diseases.

Spray performance and control efficacy against pests in paddy rice by UAV-based pesticide application: effects of atomization, UAV configuration and flight velocity.

BACKGROUND: Over the past decade, unmanned aerial vehicle (UAV) sprayers have emerged as valuable tools for pesticide application across various crops. Despite their increasing usage, the impact of several factors on spray performance and control efficacy in paddy fields warrants further investigation. This study examines atomization characteristics using a UAV spray test platform. Our evaluation of field spraying performance considers three UAV models, two nozzle types, two flight velocities, and adding methylated vegetable oil adjuvant (MVOA), in comparison with the electrical knapsack sprayer (EKS). RESULTS: Atomization characteristics demonstrated consistency within the downwash airflow field, but were influenced by spray solution, nozzle type, and spray pressure. The eight-rotor UAV sprayer excelled over the quad-rotor model in terms of spray deposition across both upper and lower rice canopies. The six-rotor UAV exhibited enhanced spray deposition, droplet density, and coverage at a flight velocity of 4 m s-1 . The choice of nozzle was pivotal; the flat fan nozzle produced finer droplets with desirable deposition and coverage, whereas the air-induction nozzle created larger droplets with consistent coverage at various flight velocities. Adding MVOA improved the physicochemical properties of the spray and its performance, yielding a more uniform distribution. When compared with the EKS, UAVs showed lower deposition but comparable spray penetration. Control efficacy with the UAV sprayer was less effective against Mythimna separata but achieved 81% efficacy against Laodelphax striatellus within 7 days. CONCLUSION: This study demonstrates that UAV sprayers, particularly when combined with tank-mix adjuvants and nozzle types, can be highly effective for controlling rice pests. © 2023 Society of Chemical Industry.

Novel RNA Viruses Discovered in Weeds in Rice Fields.

Weeds often grow alongside crop plants. In addition to competing with crops for nutrients, water and space, weeds host insect vectors or act as reservoirs for viral diversity. However, little is known about viruses infecting rice weeds. In this work, we used metatranscriptomic deep sequencing to identify RNA viruses from 29 weed samples representing 23 weed species. A total of 224 RNA viruses were identified: 39 newly identified viruses are sufficiently divergent to comprise new families and genera. The newly identified RNA viruses clustered within 18 viral families. Of the identified viruses, 196 are positive-sense single-stranded RNA viruses, 24 are negative-sense single-stranded RNA viruses and 4 are double-stranded RNA viruses. We found that some novel RNA viruses clustered within the families or genera of several plant virus species and have the potential to infect plants. Collectively, these results expand our understanding of viral diversity in rice weeds. Our work will contribute to developing effective strategies with which to manage the spread and epidemiology of plant viruses.

Genome-wide SNPs reveal the fine-scale population structure of Laodelphax striatellus in China using double-digest restriction site-associated DNA sequencing.

The small brown planthopper (SBPH), Laodelphax striatellus (Fallén) is one of the most destructive rice pests and has caused serious economic losses in China. To clarify the genetic differentiation and population genetic structure of this insect pest, we investigated the genomic polymorphisms, genetic differentiation, and phylogeography of 31 SBPH populations from 28 sampling sites from three climatic zones of China using double-digest restriction site-associated DNA sequencing (ddRADseq). In total, 2,813,221,369 high-quality paired-end reads from 306 individuals and 1925 single nucleotide polymorphisms (SNPs) were obtained. Low levels of genetic diversity and significant genetic differentiation were observed among the SBPH populations, and three genetic clusters were detected in China. Neutrality tests and bottleneck analysis provided strong evidence for recent rapid expansion with a severe bottleneck in most populations. Our work provides new insights into the genetics of the SBPH and will contribute to the development of effective management strategies for this pest.

Comparative risk of new-onset diabetes mellitus for antihypertensive drugs in elderly: A Bayesian network meta-analysis.

There is no study to compare different class of antihypertensive drugs on new-onset diabetes mellitus (NOD) in elderly. We aimed to investigate the risk of antihypertensive drugs on NOD in elderly patients. The databases were retrieved in an orderly manner from the dates of their establishment to October, 2018, including Medline, Embase, Clinical Trials, and the Cochrane Database, to collect randomized controlled trials (RCTs) of different antihypertensive drugs in elderly patients (age > 60 years). Then, a network meta-analysis was conducted using R and Stata 12.0 softwares. A total of 14 RCTs involving 74 042 patients were included. The relative risk of NOD mellitus associated with six classes of antihypertensive drugs was analyzed, including placebo, angiotensin-converting enzyme inhibitors (ACEIs), angiotensin II receptor blockers (ARBs), calcium channel blockers (CCBs), diuretics, and ß blockers. Patients with ACEIs or ARBs appeared to have significantly reduced risk of NOD compare with placebo: ACEIs (OR = 0.49, 95% CrI 0.28-0.85), ARBs (OR = 0.37, 95% CrI 0.26-0.52), while CCBs, diuretics, and ß blockers appeared to have not significantly reduced risk of NOD mellitus compare with placebo: CCBs (OR = 1.10, 95% CrI 0.85-1.60), diuretics (OR = 1.40, 95% CrI 0.92-2.50), ß blockers (OR = 1.40, 95% CrI 0.93-2.10). The SUCRA of placebo, ACEIs, ARBs, CCBs, diuretics, and ß blockers was, respectively, 65.3%, 69.3%, 92.3%, 44.1%, 12.1%, and 16.5%. According to the evidence, ARBs have an advantage over the other treatments in reducing the risk of NOD in elderly patients.