Large herbivore loss has complex effects on mosquito ecology and vector‐borne disease risk

Abstract

Loss of biodiversity can affect transmission of infectious diseases in at least two ways: by altering host and vector abundance or by influencing host and vector behaviour. We used a large herbivore exclusion experiment to investigate the effects of wildlife loss on the abundance and feeding behaviour of mosquito vectors and to explore consequences for vector-borne disease transmission. Large herbivore loss affected both mosquito abundance and blood-feeding behaviour. For Aedes mcintoshi, the dominant mosquito species in our study and a primary vector of Rift Valley fever virus (RVFV), abundance decreased with large herbivore loss, while blood feeding on humans increased. Despite an elevated human biting rate in the absence of large herbivores, we estimated that the potential for RVFV transmission to humans doubles in the presence of large herbivores. These results demonstrate that multiple effects of biodiversity loss on vectors can lead to counterintuitive outcomes for human disease risk.

Root exudate chemical cues of an invasive plant modulate oviposition behavior and survivorship of a malaria mosquito vector

“…The findings from the present study provides a foundation for unraveling how exposure of mosquito juveniles to plant allelochemicals in breeding habitats can influence adult survivorship, which is a critical determinant of vectorial capacity, a metric of transmission potential of an arthropod-borne pathogen 32 . Investigations of this environmental effects on adult survival trait alone is unlikely to provide a clear picture of disease transmission risk and further studies to incorporate other possible interacting factors in the natural setting are warranted.…”

Survival rate, blood feeding habits and sibling species composition of Aedes simpsoni complex: Implications for arbovirus transmission risk in East Africa

“…Daily survival rates were derived from estimated parity rates for each sampling period as described previously [ 14 ] based on the formula: P n = M , where P is the daily survival rate, M the parity rate and n the gonotrophic cycle (the number of days between emergence of adult females and first oviposition). A value of 3 days was assumed for this species [ 9 ]. Finally, the longevity (days) was estimated using the formula: 1/- ln L where L is the estimated survival [ 15 ].…”

“…Genomic DNA was extracted from the abdomen using the ISOLATE II Genomic DNA Kit (Bioline, Meridian Bioscience, Germany) as per the manufacturer’s instructions. DNA was amplified targeting a 500 bp fragment of the 12S mitochondrial rRNA gene using the primers 12S3F [5’-GGGATTAGATACCCCACTATGC-3’] and 12S5R [5’-TGCTTACCATGTTACGACTT-3’] [ 16 ] and as described previously [ 9 ]. PCRs in a 10 μl reaction volume comprised 2 μl 2x MyTaq Mix (Bioline, Meridian Bioscience, Germany), 10 μM of each primer, 0.2 U of Mytaq DNA polymerase and 1 μl of the template DNA (~20 ng).…”

“…These parameters provide opportunities for vector infection and efficient transmission and are the two most sensitive indicators of disease transmission potential (i.e. vectorial capacity) [ 8 , 9 ]. Because, human vector feeding must precede outbreaks, knowledge of vector host-feeding behavior is essential to our understanding of the inter-epidemic maintenance patterns of YF.…”

Grand Challenges in Vector-Borne Disease Control Targeting Vectors

“…Understanding the factors that influence vector host-feeding patterns, their abundance and number of bites an infectious host receives are critical for estimating disease transmission potential (i.e. vectorial capacity) (7,8). As part of risk assessment for emerging VBDs, studies of how changes in host abundance including humans and wildlife influence the vectorial capacity of disease vectors and potential to alter vector-borne disease transmission risk are also important challenges for future research.…”