Incompletely observed: niche estimation for six frequent European horsefly species (Diptera, Tabanoidea, Tabanidae)

Spatiotemporal analysis of equine infectious anemia and prediction of risk areas in Europe

Equine Infectious Anemia (EIA) is a vector-borne persistent viral infection in equine animals. The EIA is characterized by recurrent fever, thrombocytopenia, depression, anemia, rapid weight loss, and lower body edema. Control of EIA is achieved through the elimination or isolation of infected animals, resulting in significant economic losses. In recent years, many countries in Europe have experienced outbreaks of EIA, which could potentially develop into a new wave of epidemic and pose a significant threat to the healthy development of the equine industry. This study utilized spatiotemporal analysis techniques and ecological niche modeling to investigate the spatiotemporal distribution characteristics of historical EIA outbreaks and predict risk areas for EIA occurrence in Europe. Spatiotemporal analysis results indicate that from 2005 to 2023, the EIA outbreaks in Europe exhibit five significant spatiotemporal clusters, with hotspots concentrated in southeastern France and northwestern Italy. Ecological niche modeling reveals that western, central, and southern Europe are high-risk areas for EIA outbreaks. Annual mean temperature, annual precipitation, and horse density are important variables that influence the occurrence of EIA. The results of this study can provide decision-makers with valuable insights, helping with EIA monitoring and resource allocation.

Diversity and abundance of tabanids in Northern Spain

Tabanids (Diptera: Tabanidae) are large haematophagous flies that cause both direct (by biting nuisance) and indirect (primarily by mechanical transmission of diseases) damage to host species. Research studies on this family have received little attention in some parts of Europe. Our aims were to characterise the species richness, abundance, and peak of activity of tabanid fly species in a region of Northern Spain. Home-made canopy traps, sweep nets, and Malaise traps were employed for the collection of tabanids across four cattle farms, two equestrian centres, and two golf courses during a 3-month period in the summer of 2020. A total of 300 specimens of 27 tabanid species belonging to eight genera were identified. The most prevalent species were Haematopota pluvialis (23.3%), Tabanus eggeri (20.0%), and Tabanus bromius (8.0%). The former species was recorded biting humans and therefore should be considered of relevance to public health. Tabanids were more diverse and abundant in scrubland and grazing pastures [relative abundance (RA) =  > 10%; species richness (S) = 8-12; Shannon-Index (H´) = 1.5 - 2.1] compared to crop landscapes (RA =  < 1%; S = 0-1; H´ = 0) according to canopy traps. The tabanid population dynamics was determined to be short, with the greatest abundance and diversity concentrated in mid-late July. This study updates the checklist of this Diptera group in the Northern Spain from nine known extant species to 31 species, providing the first data on the summer peaks of activity of tabanids for this region.

Population genetics and phylogeography of Tabanus bromius (Diptera: Tabanidae)

Background

Tabanus bromius (Diptera: Tabanidae) is one of the most notable Tabanidae species of veterinary and medical importance distributed throughout the Palearctic region. In this study, we investigate the genetic diversity and the phylogeographic structure of T. bromius sampled from Turkey, Croatia, and Iran.

Methods

For this purpose, a 686-base-pair (bp) fragment of mitochondrial DNA cytochrome oxidase I gene (COI) and 1339 bp of the nuclear DNA internal transcribed spacer (ITS) were sequenced from 247 individuals representing 15 populations.

Results

The sequences generated 169 COI haplotypes and 90 ITS alleles. A higher haplotype/allele diversity (h = 0.9909 for the COI gene and Ad = 0.8193 for the ITS region) compared to a low nucleotide diversity (π = 0.020605 for COI gene and π = 0.013667 for the ITS region), present for a high number of singleton and private haplotypes/alleles imply population expansion in the past. The results of phylogenetic analysis led to the uncovering of geographically significant groupings of lineages with regard to the entrance of the species into Anatolia and the location of major geographic barriers. According to current data, the species appears to have entered Turkey from Caucasia and Iran. A molecular clock applied to the COI data suggests that T. bromius diverged from the outgroup species nearly 8.83 million years ago, around the end of the Miocene era.

Conclusions

The results of this study indicate remarkable genetic diversity across the studied range of the species. High haplotype/allele versus low nucleotide diversity and demographic analyses implied that the T. bromius populations have undergone a series of expansions and retreats in the past. Our current findings suggest that T. bromius split from outgroups around the Late Miocene. Subsequent diversification events during the climatic and environmental fluctuation times of the Late Pliocene and Early Pleistocene periods also significantly influenced the species, resulting in the formation of some major genetic lineages. The phylogenetic analyses indicate that T. bromius most likely entered Turkey from the Caucasus region and Iran.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04970-5.

A nationwide survey of the tabanid fauna of Cameroon

Background

Tabanids are a neglected group of haematophagous dipterans despite containing 4434 species, regrouped in > 144 genera. They are mechanical vectors of important pathogens, including viruses, bacteria and protozoa of humans and domesticated and wild animals. As it is > 50 years since the publication of a preliminary nationwide record of the tabanids of Cameroon identified 84 species, updated information is needed. The aim of this study was to provide current data on the species composition, abundance and distribution of tabanids in the five main agro-ecological zones (AEZs) of Cameroon.

Methods

From 2015 to 2017, a systematic entomological study using Nzi, Vavoua, Biconical and Sevi traps (n = 106) was conducted in 604 trapping points over 11,448 trap-days in the five main AEZs of Cameroon.

Results

A total of 25,280 tabanids belonging to 25 species were collected, including eight species not previously documented in Cameroon, namely Tabanus latipes (1 female), Tabanus ricardae (1 female), Tabanus fasciatus (32 females and 6 males), Haematopota pluvialis (18 females), Haematopota decora (19 females and 3 males), Haematopota nigripennis (18 females), Chrysops distinctipennis (47 females and 5 males) and Ancala fasciata (34 females and 7 males). The distribution maps of the newly identified tabanids differed between AEZs, with most tabanids collected from the Guinean savanna. The highest apparent density of tabanids was recorded in the Sudan Savanna region, and the mean apparent densities of species with sites was statistically significantly different (Student t-test: 2.519, df = 24, P = 0.019). The highest species diversity was found in the rainforest.

Conclusions

This study increased the list of tabanids recorded in Cameroon from 84 species in the preliminary record to 92 species, with most of the newly identified species occurring in the Guinea Savanna AEZ. The high diversity and abundance of tabanids in the livestock/wildlife interface areas of the rain forests and Sudan Savanna AEZs, respectively, suggest risk of mechanical transmission of pathogens. Investigations of the microbiota of tabanids in the different AEZs to define their role as disease vectors are proposed.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13071-021-04894-0.