Can landscape metrics help determine the Culicoides imicola distribution in Italy?

Abstract

Culicoides imicola is considered to be one of the main vectors of bluetongue disease in the Mediterranean Basin. However, local variations occur. For example, in Italy, C. imicola is a stable and abundant population in Sardinia and is widely distributed across the island, whilst in Tuscany on the Italian mainland, it ranges from low abundance in the west and coastal areas to absence in the eastern part of the region. Entomological surveillance data collected over 10 years were used to classify 52 sites as low to medium or high C. imicola abundance in Sardinia, and 59 sites as either positive or negative in Tuscany. The land cover was mapped from high-resolution remote sensing images using an object-based image analysis approach and a set of landscape metrics with 500 m buffers around each site. Multivariate analysis was used to test the statistical association of landscape metrics to C. imicola presence and abundance together with other eco-climatic and topographic variables. In Sardinia, 75% of the sites were correctly classified based on altitude alone and the inclusion of landscape- related variables did not improve the classification. In Tuscany, the mean annual temperature allowed classifying 70% of the positive/negative sites correctly. When landscape metrics was included in the multivariate model, an improvement up to 80% was obtained. The presence of riparian vegetation and water was found to be positively correlated with C. imicola presence, whilst forest (including the edge between the forest and cultivated areas) was found to be negatively related to the presence of C. imicola.

Geographical distribution of Culicoides (DIPTERA: CERATOPOGONIDAE) in mainland Portugal: Presence/absence modelling of vector and potential vector species

“…During spring, the existence of non-irrigated arable land favours this species appearance, probably due to the development of their pupal phases which would not survive in aquatic environments [25,26], restricting this species to flat and slow-draining regions with clay soils (nutrient-rich, water-holding soil) [27,28]. …”

“…This shows its preference for different trees and, again, for drier environments used, probably, for breeding. This species breeds in areas where sunny surfaces prevail together with low vegetation [27]. C .…”

Modelling the Abundances of Two Major Culicoides (Diptera: Ceratopogonidae) Species in the Niayes Area of Senegal

“…For C . imicola in particular; temperature [ 16 – 23 ], rainfall [ 22 – 24 ], wind speed [ 24 ], altitude [ 17 , 20 , 21 , 25 , 26 ], NDVI (normalized difference vegetation index) [ 16 , 17 , 21 , 23 , 24 , 27 , 28 ], MIR (middle infrared reflectance) [ 17 , 22 , 23 ], host densities [ 28 ] and sparse vegetation habitat [ 21 ] were associated with the presence and abundance of this species. These drivers relate to the distribution of C .…”

Composition and seasonality of Culicoides in three host environments in Rabat region (Morocco)

“…In Senegal and South Africa, this species is associated with rainfall, NDVI, temperature, wind speed and percentage cover of water bodies (Diarra et al, 2015). Other studies including environmental parameters (related to land use, landscape and climate) conducted in the Mediterranean Basin suggest that these parameters improve the prediction of habitat suitability occupied by C. imicola as well as the accuracy of abundance estimates at local scale (Ippoliti et al, 2013).…”