Tracking Community Timing: Pattern and Determinants of Seasonality in Culicoides (Diptera: Ceratopogonidae) in Northern Florida

Abstract

Community dynamics are embedded in hierarchical spatial–temporal scales that connect environmental drivers with species assembly processes. Culicoides species are hematophagous arthropod vectors of orbiviruses that impact wild and domestic ruminants. A better sense of Culicoides dynamics over time is important because sympatric species can lengthen the seasonality of virus transmission. We tested a putative departure from the four seasons calendar in the phenology of Culicoides and the vector subassemblage in the Florida panhandle. Two years of weekly abundance data, temporal scales, persistence and environmental thresholds were analyzed using a tripartite Culicoides β-diversity based modeling approach. Culicoides phenology followed a two-season regime and was explained by stream flow and temperature, but not rainfall. Species richness fit a nested pattern where the species recruitment was maximized during spring months. Midges were active year-round, and two suspected vectors species, Culicoides venustus and Culicoides stellifer, were able to sustain and connect the seasonal modules. Persistence suggests that Orbivirus maintenance does not rely on overwintering and that viruses are maintained year-round, with the seasonal dynamics resembling subtropical Culicoides communities with temporal-overlapping between multivoltine species. Viewing Culicoides-borne orbiviruses as a time-sensitive community-based issue, our results help to recommend when management operations should be delivered.

Spatio-temporal modelling of Culicoides Latreille (Diptera: Ceratopogonidae) populations on Reunion Island (Indian Ocean)

“…Interannual variations in the distribution and/or abundance of C. bolitinos , C. imicola and C. grahamii have also been highlighted thanks to 2 years of spatio-temporal dynamics simulation. Fluctuations in seasonal patterns of demographic parameters and phenology (duration of presence on husbandry location) of Culicoides can modify the risk of orbivirus transmission [ 40 , 75 ], and coincidences can be noted in Reunion Island. Indeed, C. bolitinos showed strong interannual variability resulting in a higher abundance and distribution in the western highlands during the 2016 warm season than in 2017 and 2018.…”

“…The co-occurrence of competent vectors could increase the circulation potential of a pathogen by deploying a range of different responses to environmental climatic factors and to the hosts present. Quaglia et al [ 40 ] showed that Culicoides communities can vary beyond simple seasonal variations and that the dynamics of these changes play an important role in the epidemiology of EHD in Florida. Hence, the presence of several vector or potential vector species, their wide distributions, annual and interannual change in demographic parameters, and different trophic preferences and behaviors reinforce the need to better understand the BTV and EHDV risk on Reunion Island.…”

“…Consequently, during the last decades, various studies conducted in Europe and Africa have mapped occurrence or abundance of Culicoides at a continental or country-wide scale [ 22 – 37 ] and less commonly at a local scale [ 8 , 38 , 39 ]. Variations in the demographics and blood-feeding behavior of arthropod vectors, resulting from the temporal distribution of species-specific environmental thresholds, can impact pathogen transmission and ultimately disease emergence [ 40 ]. Hence, a spatio-temporal approach is particularly useful when the risk of exposure to vectors or VBDs is clustered in time and space [ 9 ].…”

Perspectives on the Changing Landscape of Epizootic Hemorrhagic Disease Virus Control

“…In the absence of safe and efficacious vaccines, biting midge vector management remains the best available method to reduce EHDV transmission for wild cervids and domesticated animal populations such as pastured beef and dairy cattle, sheep, or captive cervids. Insect vector management (IVM) reduces biting midge populations and limits contact (feeding) events between vector insects and host animals; this will decrease virus transmission during outbreaks if the vector species are known [52,95]. Furthermore, by reducing adult midge survival, the age distribution shifts towards younger midges which are less likely to be infected and infectious when they bite host animals [96].…”

Resource Selection by Wild and Ranched White-Tailed Deer (Odocoileus virginianus) during the Epizootic Hemorrhagic Disease Virus (EHDV) Transmission Season in Florida

“…For this study, we define the EHDV transmission period as May–October. As recently summarized, hemorrhagic disease cases (which may also include Bluetongue Virus) are reported June–November, with the peak between August–October [ 18 ].…”