Browsing by Author "Wynne, Nicole Elizabeth"

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    Response to visual threats in Aedes aegypti mosquitoes
    Wynne, Nicole Elizabeth (Virginia Tech, 2020-06-04)
    Blood-feeding mosquitoes, by transmitting parasites and viruses to their hosts, kill several hundred thousand people every year. Mosquito populations are currently developing raising levels of insecticide resistance, and there is a need for a better understanding of their behavior so that new control solutions can be imagined, and existing ones can be improved. There has been a vast number of studies examining the host seeking behavior of mosquitoes, however there is a lack of knowledge concerning how mosquitoes are evading the threats their hosts pose via their defensive behaviors. Female mosquitoes are indeed in this unique position where their fitness and reproduction depend on them being able to locate hosts as well as evade them. In order to do this, they rely on sensory cues that they must be able to continuously re-evaluate during host tracking to potentially decide to quickly escape at any point during these interactions. Host seeking is mediated by multiple sensory modalities such as vision, olfaction, and thermosensation. However, it is not clear whether mosquitoes may also be using some of these same cues to identify that their host is turning into a threat. Focusing solely on visual cues in the context of escape behavior, we used a looming stimulus to elicit escape responses from the Yellow Fever mosquito, Aedes aegypti. A virtual reality environment was adapted from previous work, to display the looming stimulus while the mosquito is in a variety of conditions (i.e., landed, in free or tethered flight). Results from these experiments allowed us to characterize the escape responses of mosquitoes, by determining the angles and distances to the stimuli that will most likely trigger an avoidance response.
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    Variations in Time-Dependent Mosquito-Host Interactions Across Aedes Species
    Wynne, Nicole Elizabeth (Virginia Tech, 2023-06-27)
    Virtually all organisms exhibit circadian rhythms, this includes mosquitoes. Many aspects of their biology are under the control of their circadian clocks like their vision, olfaction, host-seeking, mating, oviposition, metabolism, locomotion, and more. However, how the circadian clock regulates mosquito-host interactions and adapts to specific environmental conditions remains largely unknown, despite its importance to vector disease control. Here, we relied on a multidisciplinary, integrative, and comparative approach to shed light on the mechanisms underlying mosquitoes adaptations to various temporal niches. We use CRISPR/Cas9 to knockout timeless in Aedes aegypti and show this mutation causes an increase in their free running periods under continuous darkness conditions. External factors can also influence a vector's activity pattern like climate, light pollution, as well as host preference and availability. To investigate the influence these factors have on activity patterns, we compare the activity patterns of multiple lab rear strains of Aedes albopictus as well as two field collected populations of Aedes japonicus. Our results suggest host availability and light pollution could cause the differences in activity profiles that we observed. With vision playing an important role in both circadian rhythms, host seeking, and threat detection, we compared a nocturnal mosquito (Aedes japonicus) and a diurnal mosquito (Aedes aegypti). We introduced a looming visual stimulus in an LED arena and found Aedes aegypti to be more responsive to the looming stimulus than Aedes japonicus. Finally, the underlying mechanisms that mediate this threat detection and escape behavior were examined, revealing a possible candidate for a giant fiber neuron in Aedes aegypti. Overall these results provide novel insights into mosquito biology that have the potential to be applied towards vector control methods.