# Culicoides insignis in Ecuador: Molecular identification of blood meals and detection of bluetongue virus

## TL;DR

This study confirms that Culicoides insignis midges in Ecuador feed on humans and horses and provides the first molecular evidence of bluetongue virus in these insects.

## Contribution

First molecular evidence of bluetongue virus in Culicoides insignis from Ecuador.

## Key findings

- Culicoides insignis feeds on horses and humans in the Ecuadorian Amazon.
- BTV RNA was detected in one unengorged C. insignis female, indicating high viral load.
- C. insignis is a potential vector of BTV in Ecuador.

## Abstract

Bluetongue virus (BTV) is an Orbivirus transmitted by Culicoides biting midges and is the causative agent of bluetongue disease in wild and domestic ruminants. Culicoides insignis is the primary vector of BTV in Florida, Central America, the Caribbean, and South America. In Ecuador, recent investigations have reported the presence of BTV in cattle and identified C. insignis as the dominant species in localities from the Amazon Basin and Andean foothills. Understanding the host-feeding patterns of blood-feeding insects and evaluating their role in pathogen transmission are essential for elucidating the epidemiology of vector-borne diseases. To that end, we investigated the presence of BTV in unengorged C. insignis females collected in two localities: Cotundo, where BTV had previously been reported in cattle, and Paraiso Escondido located near (∼35 km) a site with a known history of BTV circulation. A total of 1773 female Culicoides spp. specimens were collected, of which 326 (18.38 %) were C. insignis. We identified the blood meal sources of engorged C. insignis females from both localities. Our results provide additional evidence to support the role of C. insignis as vector of BTV in Ecuador.

Image 1

•Culicoides insignis is abundant in Cotundo, an Ecuadorian locality with a history of BTV transmission.•Molecular identification of blood meals confirmed that C. insignis feeds on horses and humans in the Ecuadorian Amazon.•The RT-qPCR detection of BTV RNA in one unengorged C. insignis female suggests a high viral load.•This is the first molecular evidence of BTV in C. insignis from Ecuador.•Culicoides insignis could be a potential vector of BTV in Ecuador.

Culicoides insignis is abundant in Cotundo, an Ecuadorian locality with a history of BTV transmission.

Molecular identification of blood meals confirmed that C. insignis feeds on horses and humans in the Ecuadorian Amazon.

The RT-qPCR detection of BTV RNA in one unengorged C. insignis female suggests a high viral load.

This is the first molecular evidence of BTV in C. insignis from Ecuador.

Culicoides insignis could be a potential vector of BTV in Ecuador.