Human-landing rate, gonotrophic cycle length, survivorship, and public health importance of Simulium erythrocephalum in Zaragoza, northeastern Spain

Abstract

Background Simulium (Boophthora) erythrocephalum (De Geer, 1776) is one of the blackfly species responsible for major public health problems in Europe. Blackfly outbreaks of this species are becoming more frequent, threatening public health in Spain. In the present study, bionomic parameters of S. erythrocephalum in northeastern Spain were estimated.Methods Simulium erythrocephalum was collected from May through June 2015 in Zaragoza, Spain, using the human-landing-collection (HLC) method. Daily pattern of total and parous landing activity was estimated, as was the gonotrophic cycle (GC) length and survivorship (S) rate, using time series analysis.ResultsHost-seeking females of S. erythrocephalum showed a bimodal human-landing activity pattern, with a minor and major peak at dawn and dusk, respectively; there was a significant negative association between human daily landing rate and temperature (P = 0.003) and solar radiation (P < 0.001). Overall, a daily landing rate (DLR) of 34 lands/person/day was estimated. Series of sequential data analysis on parity showed the highest significant (P < 0.001) correlation indices (r = 0.45 and r = 0.39 for raw and filtered data) for a 2-day time lag, indicating that the GC length corresponded to 2 days. Daily survivorship and parity rate were 0.85 and 0.72, respectively.Conclusions Simulium erythrocephalum was confirmed as a nuisance species in Zaragoza, using the HLC method for the first time in Spain. The data offer insights into the ecology of S. erythrocephalum, which can improve management strategies of this pest in Spain.

Mating behaviour of Simulium erythrocephalum (De Geer, 1776) (Diptera: Simuliidae) in Zaragoza (Spain)

“…The optimal temperature for host-seeking activity of S. erythrocephalum was between 22.17 to 27.35°C in the evening. With regard to solar radiation, blackflies showed host-seeking activity at values below 123.51 W/m 2 (evening hours) with the most intensive host-seeking behaviour at solar radiation of 8 W/m 2 , recorded at 20:30 PM, in conditions of dim sunlight (Ruiz-Arrondo et al 2017). In this context, in our study the first swarm was observed at the illuminance value of 300 lux and the last one at 45 lux.…”

“…Also, Peterson (1959), noted that males of Simulium arcticum (Malloch, 1914) (complex of nearctic species) were swarming during the daylight at 14:30 over the headwaters of the Provo River in Utah, USA. According to Ruiz-Arrondo et al (2017), the bimodal daily landing-activity pattern of S. erythrocephalum was affected by temperature and solar radiation.…”

“…1 C, D). Along with the HLC study, the mating behaviour observations were conducted during the period of 12 consecutive days, from May 29th to June 9th, 2015, starting at 6:30 AM and ending at 20:30 PM (Central European Summer Time, UTC + 2h) each day (for more information see Ruiz-Arrondo et al 2017).…”

“…Simulium erythrocephalum (De Geer, 1776), which is widely distributed in 36 countries in the Paleartic ecozone (Adler & Croskey 2018), is a highly anthropophilic species and it is responsible for blackfly outbreaks in Spain (Ruiz-Arrondo et al 2014). The high abundance of blackfly adults in different regions of Spain means an emergent public health problem in the country, which entails, among other consequences, the increase of number of medical consultations due to arthropod bites (Ruiz-Arrondo et al 2017).…”

La influencia de la vegetación acuática en el desarrollo de las poblaciones de "Simulium erythrocephalum" (De Geer, 1776) (Diptera, Simuliidae) en Madrid: su relación con las emergencias masivas de mosca negra.

“…Hasta ahora, son escasos los trabajos que han abordado este tema, aunque merece ser reseñado el de Werner (2003), que incluye un repaso de la vegetación de hidrófitos y helófitos del río Oder y sus tributarios en Alemania, como sustrato de otras especies antropófilas. En España, se han realizado varios estudios o informes, sobre diferentes ríos, como son los casos del Ebro y del Henares, que tienen problemas asociados a la proliferación de hidrófitos (13) (14) que pueden afectar a los usos del agua y a la salud ambiental de los ecosistemas acuáticos. Entre estos problemas se incluye la proliferación de dipteros picadores, como es el caso de algunas especies de simúlidos.…”