Adoption of Best Management Practices for Grapevine Leafroll and Red Blotch Diseases: A Survey of West Coast Growers

Grapevine leafroll (GLD) and red blotch (RBD) diseases threaten the sustainability of the USA wine grape industry. To understand factors influencing the adoption of disease management practices, we surveyed wine grape industry professionals in California, Oregon, and Washington (n=154). Economic factors were the fundamental cost of implementing management practices and the ability to sell product from diseased vines (salability). Respondents with reduced salability were more likely to adopt virus testing, replace infected vines, and view these practices as economically favorable. Salability was a strong driver for adoption among Californian respondents, but lesser so in Washington where wineries appeared more willing to accept infected product. Respondents who had acquired technical knowledge of disease ecology were more likely to adopt management practices and to perceive them as economical. Conversely, when there was a lack of knowledge of GLD ecology, notably that mealybugs transmit the pathogen, , adoption was reduced and practices were considered less economical,. Factors affecting adoption were broadly generalizable across diseases. However, knowledge of GLD ecology was more strongly associated with adoption, likely reflecting the remaining knowledge gaps in RBD related to vector ecology and field spread. An emphasis on grower knowledge acquisition and the development of economical disease management practices can improve adoption of best management practices for viral diseases of grapevine.

Density assessment and reporting for Phlebotomus perniciosus and other sand fly species in periurban residential estates in Spain

Green periurban residential areas in Mediterranean countries have flourished in the last decades and become foci for leishmaniasis. To remedy the absence of information on vector ecology in these environments, we examined phlebotomine sand fly distribution in 29 sites in Murcia City over a 3-year period, including the plots of 20 detached houses and nine non-urbanized sites nearby. We collected 5,066 specimens from five species using “sticky” interception and light attraction traps. The relative frequency of the main Leishmania infantum vector Phlebotomus perniciosus in these traps was 32% and 63%, respectively. Sand fly density was widely variable spatially and temporally and greatest in non-urbanized sites, particularly in caves and abandoned buildings close to domestic animal holdings. Phlebotomus perniciosus density in house plots was positively correlated with those in non-urbanized sites, greatest in larger properties with extensive vegetation and non-permanently lived, but not associated to dog presence or a history of canine leishmaniasis. Within house plots, sand fly density was highest in traps closest to walls. Furthermore, the study provides a guideline for insect density assessment and reporting and is envisioned as a building block towards the development of a pan-European database for robust investigation of environmental determinants of sand fly distribution.

Prediction of species composition ratios in pooled specimens of the Anopheles Hyrcanus group using quantitative sequencing

Background Plasmodium vivax is transmitted by members of the Anopheles Hyrcanus Group that includes six species in the Republic of Korea: Anopheles sinensis sensu stricto (s.s.), Anopheles pullus, Anopheles kleini, Anopheles belenrae, Anopheles lesteri, and Anopheles sineroides. Individual Anopheles species within the Hyrcanus Group demonstrate differences in their geographical distributions, vector competence and insecticide resistance, making it crucial for accurate species identification. Conventional species identification conducted using individual genotyping (or barcoding) based on species-specific molecular markers requires extensive time commitment and financial resources. Results A population-based quantitative sequencing (QS) protocol developed in this study provided a rapid estimate of species composition ratios among pooled mosquitoes as a cost-effective alternative to individual genotyping. This can be accomplished by using species- or group-specific nucleotide sequences of the mitochondrial cytochrome C oxidase subunit I (COI) and the ribosomal RNA internal transcribed spacer 2 (ITS2) region as species identification alleles in a two-step prediction protocol. Standard genomic DNA fragments of COI and ITS2 genes were amplified from each Anopheles species using group-specific universal primer sets. Following sequencing of the COI or ITS2 amplicons generated from sets of standard DNA mixtures, equations were generated via linear regression to predict species-specific nucleotide sequence frequencies at different positions. Species composition ratios between An. sineroides, An. pullus and An. lesteri were estimated from QS of the COI amplicons based on the mC.260A, mC.122C and mC.525C alleles at the first step, followed by the prediction of species composition ratios between An. sinensis, An. kleini and An. belenrae based on QS of the ITS2 amplicons using the rI.370G and rI.389T alleles. The COI copy number was not significantly different between species, suggesting the reliability of COI-based prediction. In contrast, ITS2 showed a slightly but significantly higher copy number in An. belenrae, requiring an adjustment of its predicted composition ratio. A blind test proved that predicted species composition ratios either from pooled DNA specimens or pooled mosquito specimens were not statistically different from the actual values, demonstrating that the QS-based prediction is accurate and reliable. Conclusions This two-step prediction protocol will facilitate rapid estimation of the species composition ratios in field-collected Anopheles Hyrcanus Group populations and is particularly useful for studying the vector ecology of Anopheles population and epidemiology of malaria.

Highlights of Medical Entomology, 2020

Medical Entomology as a field is inherently global – thriving on international and interdisciplinary collaborations and affected dramatically by arthropod and pathogen invasions and introductions. This past year also will be remembered as the year in which the SARS-CoV-2 COVID-19 pandemic affected every part of our lives and professional activities and impacted (or changed, sometimes in good ways) our ability to collaborate and detect or respond to invasions. This incredible year is the backdrop for the 2020 Highlights in Medical Entomology. This article highlights the broad scope of approaches and disciplines represented in the 2020 published literature, ranging from sensory and chemical ecology, population genetics, impacts of human-mediated environmental change on vector ecology, life history and the evolution of vector behaviors, to the latest developments in vector surveillance and control.

Gene-drive suppression of mosquito populations in large cages as a bridge between lab and field

CRISPR-based gene-drives targeting the gene doublesex in the malaria vector Anopheles gambiae effectively suppressed the reproductive capability of mosquito populations reared in small laboratory cages. To bridge the gap between laboratory and the field, this gene-drive technology must be challenged with vector ecology.Here we report the suppressive activity of the gene-drive in age-structured An. gambiae populations in large indoor cages that permit complex feeding and reproductive behaviours.The gene-drive element spreads rapidly through the populations, fully supresses the population within one year and without selecting for resistance to the gene drive. Approximate Bayesian computation allowed retrospective inference of life-history parameters from the large cages and a more accurate prediction of gene-drive behaviour under more ecologically-relevant settings.Generating data to bridge laboratory and field studies for invasive technologies is challenging. Our study represents a paradigm for the stepwise and sound development of vector control tools based on gene-drive.

EVALUATION OF DYNATRAP® DT160 AS AN INEXPENSIVE ALTERNATIVE TO CDC TRAPS FOR ADULT MOSQUITO MONITORING IN MALI, WEST AFRICA

Mosquito monitoring traps (i.e., CDC light traps) are crucial tools for basic vector ecology research, risk assessment, and vector control programs. Unfortunately, they are expensive which is often an issue in projects conducted in developing countries. Therefore, it would be desirable to have reliable but inexpensive alternatives based on existing consumer products. We compared an off-the-shelf DynaTrap (model DT160, CCFL tube 365 ± 3 nm UV) modified to fit a CDC trap collection bag and to use a 12V power supply, with two commonly used CDC traps: CDC Miniature Light Trap Model 512 (incandescent light, 6 Volt) and CDC Miniature Downdraft Blacklight (UV) Trap Model 912 (4-Watt blue-black-light tube, 12 Volt), in different ecological settings in southwest (Kenieroba) and northwest (Nioro du Sahel) Mali, West Africa. In northwest Mali, the modified DynaTrap caught a mean of 20.67 ± 2.8 females and 5.38 ± 1.0 male Aedes aegypti which was 16.55% and 10.78% more, respectively, than the CDC incandescent trap (control). The DynaTrap caught a mean of 29.75 ± 2.8 female and 17.92 ± 3.5 male Culex quinquefasciatus. which was 47.76% and 20.70% more than the control CDC incandescent trap. The DynaTrap caught a mean of 2.46 ± 0.5 females and 1.63 ± 0.6 males and 10.16% and 2.45% more female and male An. gambiae s.l., respectively, than the CDC incandescent trap. Trap and catch means were lower at the southwest Mali site. However, trap catch proportions by sex were similar to those in the northwest. The modified DynaTrap outperformed both CDC monitoring traps for less than one third of the cost including the cost of the DynaTrap modifications.

The Specificity of the Persistent IgM Neutralizing Antibody Response in Zika Viral Infections Among Individuals with Prior Dengue Virus Exposure

Dengue viruses (DENV) and Zika virus (ZIKV) are related mosquito-borne flaviviruses with similar disease manifestations, vector ecology and geographic range. The ability to differentiate these viruses serologically is vital due to the teratogenic nature of ZIKV and the potential confounding of pre-existing cross-reactive anti-DENV antibodies. Here we illustrate the kinetics of the IgM neutralizing antibody (NAb) response using longitudinal samples ranging from acute ZIKV infection to late convalescence from individuals with evidence of prior DENV infection. By serially depleting antibody isotypes prior to neutralization assay, we determined that IgM contributes predominantly to ZIKV neutralization, and it is less cross-reactive than the IgG NAb. The IgM NAb peaked around 14 days (95% CI: 13-15) with a median duration of 257 days (95% CI: 133-427). These results demonstrate the persistence of IgM NAb after ZIKV infections and imply its potential role in diagnosis, vaccine evaluation, serosurveillance, and research of flaviviral-host interactions.

Spatial connectivity in mosquito-borne disease models: a systematic review of methods and assumptions

Spatial connectivity plays an important role in mosquito-borne disease transmission. Connectivity can arise for many reasons, including shared environments, vector ecology and human movement. This systematic review synthesizes the spatial methods used to model mosquito-borne diseases, their spatial connectivity assumptions and the data used to inform spatial model components. We identified 248 papers eligible for inclusion. Most used statistical models (84.2%), although mechanistic are increasingly used. We identified 17 spatial models which used one of four methods (spatial covariates, local regression, random effects/fields and movement matrices). Over 80% of studies assumed that connectivity was distance-based despite this approach ignoring distant connections and potentially oversimplifying the process of transmission. Studies were more likely to assume connectivity was driven by human movement if the disease was transmitted by an Aedes mosquito. Connectivity arising from human movement was more commonly assumed in studies using a mechanistic model, likely influenced by a lack of statistical models able to account for these connections. Although models have been increasing in complexity, it is important to select the most appropriate, parsimonious model available based on the research question, disease transmission process, the spatial scale and availability of data, and the way spatial connectivity is assumed to occur.