Seasonal dynamics of Phlebotomus neglectus (Diptera: Psychodidae) in cave microhabitats in Romania and the rediscovery of Sergentomyia minuta (Rondani, 1843) after 50 years

Phlebotomine sand flies (Diptera: Psychodidae) of Bosnia and Herzegovina: distribution, ecology and environmental preferences

Sand flies (Diptera: Phlebotominae) are the principal vectors for the protozoan parasites Leishmania spp. and for phleboviruses. The sand fly fauna on the Balkan Peninsula, including Bosnia and Herzegovina (BIH), is diverse and the circulation of Leishmania infantum as well as phleboviruses has been proven. However, recent data on the sand fly fauna in BIH are scarce. In this study, we surveyed understudied regions in central and northeastern BIH to update the sand fly distribution and gain insights into the ecological and environmental factors shaping their appearance. CDC light trapping was conducted in 2022 and 2023 and a combination of morphological and molecular methods (cytochrome oxidase I barcoding) was performed for species identifications. We mapped the currently known distribution, modelled climatic suitability patterns and performed environmental analyses by applying machine learning methods. In addition, we analyzed blood meals by host gene sequencing and MALDI-TOF peptide mass mapping and screened for Leishmania spp. DNA and Phlebovirus RNA. Altogether, 591 sand flies of four species were trapped, predominantly Phlebotomus neglectus (97 %), but also Ph. balcanicus, Ph. mascittii, and Ph. papatasi. Records of seven sand fly species known to be endemic were plotted onto distribution maps based on 101 datapoints, identifying Ph. neglectus as the overall predominant species. The environmental analyses of sand fly species indicated variation in altitudinal, thermal, and precipitation conditions across the sand fly-positive sites. Phlebotomus simici, Phlebotomus tobbi, and Sergentomyia minuta are typically found exclusively in Mediterranean and subtropical climate zones, whereas other species typically inhabit continental regions. The Inverse Distance Weighted (IDW) interpolation of sand fly species numbers and Shannon entropy values suggested the southeastern coastal region of BIH as a primary focus for sand fly occurrence. This finding was corroborated by modeled average climatic suitability patterns for sand flies, depicting four distinct meso-regions for sand fly occurrence. The results of the ensemble method highlight the importance of annual precipitation to distinguish between positive and negative sand fly trapping sites in BIH. In total, 55 blood meals of two sand fly species, Ph. neglectus and Ph. balcanicus, were analyzed and five host species identified. Our comprehensive assessment of ecological and environmental preferences of sand flies in BIH may support further entomological surveys and help to better understand and evaluate potential hot spots of disease transmission in the country.

A cross-sectional study on phlebotomine sand flies in relation to disease transmission in the Republic of Kosovo

Sand flies (Diptera: Psychodidae: Phlebotominae) are blood-feeding insects that transmit the protozoan parasites Leishmania spp. and various arboviruses. The Balkan region, including the Republic of Kosovo, harbours a diverse sand fly fauna. Vector species of Leishmania infantum as well as phleboviruses are endemic; however, recent data are scarce. We performed a cross-sectional study to update the current sand fly distribution in Kosovo and assess biological as well as environmental factors associated with sand fly presence. CDC light trapping was conducted at 46 locations in 2022 and 2023, specifically targeting understudied regions in Kosovo. Individual morphological species identification was supported by molecular barcoding. The occurrence data of sand flies was used to create distribution maps and perform environmental analyses, taking elevation, wind speed and climate-related factors into account. In addition, PCR-based blood meal analysis and pathogen screening were conducted. Overall, 303 specimens of six sand fly species were trapped, predominated by Phlebotomus neglectus (97%). Barcodes from eight of nine known endemic sand fly species were obtained. Combining our data with previous surveys, we mapped the currently known sand fly distribution based on more than 4000 specimens at 177 data points, identifying Ph. neglectus and Ph. perfiliewi as the predominant species. Environmental analyses depicted two geographical groups of sand flies in Kosovo, with notable differences between the species. In total, 223 blood meals of five sand fly species were analysed. Of seven identified host species, the predominant blood meal source was observed to be cattle, but the DNA of dogs and humans, among others, was also detected. This study assessed biological as well as ecological factors of sand fly occurrence, which should help better understand and evaluate potential hot spots of disease transmission in Kosovo.

Distribution of Phlebotomine Sand Flies (Diptera: Psychodidae) in the Lombardy Region, Northern Italy

Simple Summary

Pathogens transmitted to humans and animals by Phlebotomines are relatively neglected, as they cause infectious diseases which represent an underestimated burden in most European countries. Several sand fly species are competent vectors of Leishmaniasis, an endemic disease that has spread widely throughout the Mediterranean region in conjunction with sand flies’ movements. In the Lombardy region, information on sand flies is poor and/or outdated. Therefore, the present study was undertaken to preliminarily ascertain the species composition, distribution, and diversity in representative Lombardy localities. The sampling took advantage of regional surveillance plans namely, West Nile virus and leishmaniasis monitoring plans. A focused sampling was also performed in areas identified as favorable for vector presence. Sampling was conducted using CO₂–CDC traps conducted every two and/or three weeks. From trapping for the West Nile monitoring plan, 21 out of 44 capture sites were positive for sand flies, while for the leishmaniasis monitoring plan, 11 out of the 40 trapping sites detected sand flies’ presence. Specimen identification was conducted by identifying morphological features. Phlebotomus perniciosus was the most abundant species (87.76% of specimens collected). Adequate and well-structured monitoring of sand fly populations is essential to provide information about distribution patterns of vector species present in defined geographical areas, as they could enhance pathogen circulation.

Abstract

This study investigated the species composition and density of sand flies in the Lombardy region (Northern Italy). Sand flies were collected using CDC traps baited with CO₂ (CO₂–CDC traps) between June and August 2021. A total of 670 sand flies were collected. The specimens were identified as seven species belonging to two genera, Phlebotomus and Sergentomyia, namely, S. minuta, Ph. perniciosus, Ph. perfiliewii, Ph. neglectus, Ph. mascitti, Ph. papatasi, and Ph. ariasi. Phlebotomus perniciosus was the most abundant species (87.76%), followed by Ph. perfiliewii (7.31%), Ph. neglectus (3.13%), S. minuta (0.75%), Ph. mascitti (0.6%), Ph. papatasi (0.3%), and Ph. ariasi, for which only one specimen was identified. Among these identified species, five are considered vectors of Leishmania, which causes cutaneous and visceral leishmaniasis. As vector presence increases the risk of vector-borne leishmaniasis, these results suggest that Northern Italy could be a potential area of pathogen circulation over the next few years. These preliminary results suggest that the risk of borne leishmaniasis is high in this region of Northern Italy. Monitoring the distribution of sand fly species in areas suitable for their persistence is important for control programs aimed at reducing the risk of leishmaniasis infection.