Bluetongue Virus Serotype 3 and Schmallenberg Virus in Culicoides Biting Midges, Western Germany, 2023.

In October 2023, bluetongue virus serotype 3 (BTV-3) emerged in Germany, where Schmallenberg virus is enzootic. We detected BTV-3 in 1 pool of Culicoides biting midges collected at the time ruminant infections were reported. Schmallenberg virus was found in many vector pools. Vector trapping and analysis could elucidate viral spread.

Enhancing arthropod occurrence in wheat cropping systems: the role of non-chemical pest management and nitrogen optimization.

This study analyzes arthropod biomass and abundance to track the changes in arthropod occurrence in relation to pesticide use in three winter wheat cropping systems managed at different intensities (organic, conventional, and hybrid). Arthropod occurrence was surveyed using three collection tools: sweeping nets, eclector traps, and yellow traps. Sampling was conducted over three years from 2020 to 2022 with 588 samples collected. The wet weight of the captured organisms was determined and arthropod abundance calculated. The application of a NOcsPS (no chemical-synthetic pesticides) strategy, a new hybrid cultivation method realized with optimized use of nitrogen fertilizers but without chemical-synthetic pesticides, showed a higher arthropod occurrence and performed more convincingly regarding produced arthropod biomass and abundance than the other cropping variants. The results also demonstrate a dependence of the obtained insect indices on the collection method. Although arthropod biomass and abundance correlated for all collection methods, the combination of various methods as well as multiple procedures of sample analysis gives a more realistic and comprehensive view of the impact of the wheat cultivation systems on the arthropod fauna than one-factor analyses.

Large-Scale Cytochrome C Oxidase Subunit I Gene Data Analysis for the Development of a Multiplex Polymerase Chain Reaction Test Capable of Identifying Biting Midge Vector Species and Haplotypes (Diptera: Ceratopogonidae) of the Culicoides Subgenus Avaritia Fox, 1955.

The emergence of culicoid-transmitted bluetongue and Schmallenberg viruses in several European countries demonstrated the ability of indigenous biting midge species to transmit pathogens. Entomologic research programs identified members of the Obsoletus Group (Culicoides subgenus Avaritia) as keyplayers in disease epidemiology in Europe. However, morphological identification of potential vectors is challenging due to the recent discovery of new genetic variants (haplotypes) of C. obsoletus sensu stricto (s.s.), forming distinct clades. In this study, 4422 GenBank entries of the mitochondrial cytochrome c oxidase subunit I (COI) gene of subgenus Avaritia members of the genus Culicoides were analyzed to develop a conventional multiplex PCR, capable of detecting all vector species and clades of the Western Palearctic in this subgenus. Numerous GenBank entries incorrectly assigned to a species were identified, analyzed and reassigned. The results suggest that the three C. obsoletus clades represent independent species, whereas C. montanus should rather be regarded as a genetic variant of C. obsoletus s.s. Based on these findings, specific primers were designed and validated with DNA material from field-caught biting midges which achieved very high diagnostic sensitivity (100%) when compared to an established reference PCR (82.6%).

Improvements of weaned pigs barn hygiene to reduce the spread of antimicrobial resistance.

The spread of antimicrobial resistance (AMR) in animal husbandry is usually attributed to the use of antibiotics and poor hygiene and biosecurity. We therefore conducted experimental trials to improve hygiene management in weaned pig houses and assessed the impact on the spread. For each of the two groups examined, the experimental group (EG) and the control group (CG), three replicate batches of piglets from the same pig breeder, kept in pre-cleaned flat decks, were analyzed. In the flat decks of the experimental groups, the hygiene conditions (cleaning, disinfection, dust removal and fly control) were improved, while regular hygiene measures were carried out in the control groups. The occurrence and spread of AMR were determined in Escherichia coli (E. coli; resistance indicator) using cultivation-dependent (CFU) and -independent (qPCR) methods as well as whole genome sequencing of isolates in samples of various origins, including feces, flies, feed, dust and swabs. Surprisingly, there were no significant differences (p > 0.05) in the prevalence of resistant E. coli between the flat decks managed with conventional techniques and those managed with improved techniques. Selective cultivation delivered ampicillin- and sulfonamide-resistant E. coli proportions of up to 100% and 1.2%, respectively. While 0.5% E. coli resistant to cefotaxime and no ciprofloxacin resistance were detected. There was a significant difference (p < 0.01) in the abundance of the blaTEM-1 gene in fecal samples between EG and CG groups. The colonization of piglets with resistant pathogens before arrival, the movement of flies in the barn and the treatment of bacterial infections with antibiotics obscured the effects of hygiene improvement. Biocide tolerance tests showed no development of resistance to the farm regular disinfectant. Managing hygiene alone was insufficient for reducing antimicrobial resistances in piglet rearing. We conclude that the complex factors contributing to the presence and distribution of AMR in piglet barns underscore the necessity for a comprehensive management strategy.

Viral RNA in Mosquitoes (Diptera: Culicidae) Collected between 2019 and 2021 in Germany.

Due to globalisation and climate change, mosquito-borne pathogens are emerging in new areas on all continents, including Europe, which has recently faced outbreaks of dengue, chikungunya and West Nile fever. The present study complements previous investigations to evaluate the circulation of mosquito-borne viruses in Germany, with the aim of identifying potential vector species and risk areas. Mosquitoes collected from 2019 to 2021 and identified to species or species group level were screened for viruses of the families Flaviviridae, Peribunyaviridae and the genus Alphavirus of the family Togaviridae. In total, 22,528 mosquitoes were examined, thus providing the most comprehensive study on West Nile virus (WNV) circulation so far in the German mosquito population. Usutu virus (USUV) RNA was detected in six samples, Sindbis virus (SINV) RNA in 21 samples and WNV RNA in 11 samples. Samples containing RNA of USUV and WNV consisted of mosquitoes collected in the East German federal states of Brandenburg, Saxony and Saxony-Anhalt, while samples with RNA of SINV originated from more widespread locations. Although minimum infection rates have remained relatively low, the intensity of virus circulation appears to be increasing compared to previous studies. Continuous mosquito screening contributes to the early detection of the introduction and spread of mosquito-borne pathogens.