St Kitts Mosquito Survey and Model November 2017 to March 2019

Background: High quality mosquito surveys that collect fine resolution
local data on mosquito species’ abundances provide baseline data to help
us understand potential host-pathogen-mosquito relationships, accurately
predict disease transmission, and target mosquito control efforts in areas
at risk of mosquito borne diseases. Methods: As part of an investigation
into arboviral sylvatic cycles on the Caribbean island of St. Kitts, we
carried out an island wide mosquito survey from November 2017 to March
2019. Using Biogents Sentinel 2 and miniature CDC light traps that were
set monthly and run for 48 hour intervals, we collected mosquitoes from a
total of 30 sites distributed across the five common land covers on the
island (agricultural, mangrove, rainforest, scrub, and urban). We
developed a mixed effects negative binomial regression model to predict
the effects of land cover, seasonality, and precipitation on observed
counts of the most abundant mosquito species we found. Results: We
captured 10 of the 14 mosquito species reported on the island, the four
most abundant being Aedes taeniorhynchus , Culex quinquefasciatus , Aedes
aegpyti , and Deinocerites magnus. Sampling in the mangroves yielded the
most mosquitoes, with Ae. taeniorhynchus, Cx. quinquefasciatus, and De.
magnus predominating. Aedes aegypti was recovered primarily from urban and
agricultural habitats, but also at lower frequency in other land covers.
Psorophora pygmaea and Toxorhynchites guadeloupensis were only captured in
scrub habitat. Capture rates in rainforests were low. Our models indicated
the relative abundance of the four most common species varied seasonally
and with land cover. They also suggested that the extent to which monthly
average precipitation influenced counts varied according to species.
Conclusions: This study demonstrates there is high seasonality in mosquito
abundances and that land cover influenced the distribution and abundance
of mosquito species on St. Kitts. Further, human-adapted mosquito species
(e.g. Ae. aegypti and Cx. quinquefasciatus ) that are known vectors for
many human relevant pathogens are the most wide-spread (across land
covers) and the least responsive to seasonal variation in precipitation.