Seasonality of Sand Flies (Diptera: Psychodidae) in Cave Microhabitats and The Rediscovery of Sergentomyia Minuta (Rondani, 1843) After Fifty Years

Abstract

\n Background: In a countrywide study with the aim to update the knowledge on diversity of sand fly species in Romania, a sand fly population was observed in an isolated system of cave microhabitats. The caves are located in the protected area of Canaraua Fetii, Dobrogea region, southeastern Romania. The highest sand fly diversity was recorded at the above-mentioned area between 1968 and 1970. This work presents an abundance study, which was conducted in order to estimate the seasonal variation of the sand fly species in correlation with the particular environmental factors of the isolated system of cave microhabitats.Methods: Sand flies were collected between May and October 2020 from one trapping site of interest, from Canaraua Fetii. The trapping site consisted of a system of cave entrances. CDC miniature light traps, and sticky traps were used to collect insects from the exterior walls of the cave entrances. Species identification of collected sand flies was done using morphological keys. Statistical analysis of the trapping and climatic data was performed.Results: From all collected sand flies, 99.63% (818/821) were Phlebotomus neglectus, 0.12% (1/821) Ph. balcanicus, and 0.25% (2/821) Sergentomyia minuta. Sand fly activity was firstly observed in 2nd of July and lastly in 24th of September. A monomodal abundance trend was present, with the peak activity between 16th and 17th of July. The analysis of the climatic data showed correlations between the total number of captured sand flies and both, average temperature and average relative humidity. The total number of collected specimens was statistically higher when CDC miniature light traps were used compared to sticky traps. The number of females on the sticky traps was significantly higher than the number of males on the same trap type. When compared with the sticky traps, a significantly higher number of males were collected by CDC miniature light traps. This is the first record of Se. minuta in Romania after 50 years of no records (despite the trapping effort of the last five years in the country). Also, Ph. sergenti, previously present in this location, was not found.Conclusions: In the investigated natural habitat, the diversity of the sand fly species appears to have changed, with the predominance of Ph. neglectus instead of Ph. balcanicus and Se. minuta (recorded as the two predominant species in 1968-1970). A monomodal abundance trend was observed as in other regions of the country. The sand fly activity in this particular cave microhabitat appears to be longer than in other regions in Romania. A longer sand fly activity increases the zoonotic risk of various pathogenic species’ transmission, with an impact in the public health, as sand flies are important insect vectors.