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The curious case of nasophilia in Sabethes mosquitoes: Mechanisms and cues of a successful blood meal, exclusively from blood host facial features
O'Brien-Stoffa, Connor
Ward, Shawn
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Denver, CO
Metropolitan State University of Denver
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Conference Papers ( sobekcm )


Collected for Auraria Institutional Repository by the Self-Submittal tool. Submitted by Matthew Mariner.
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Faculty mentor: Robert Hancock
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Subject: Biology

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The curious case of nasophilia in Sabethes mosquitos: Mechanisms and cues of a successful blood meal, exclusively from blood host facial features Department of Biology, Metropolitan State University of Denver, Denver, Colorado Undergraduate Research Stoffa, Shawn Ward Dr. Robert. G. Hancock Contact for questions: = P value>0.05 = P value<0.05 = P value<0.0005 Fig. 1B Fig. 2B Diurnal South/Central American tropical canopy mosquitoes: the blue and silver S. cyaneus (Fig. 1B ) is a weak zika vector. S. chloropterus ( Fig. 2B ) is the green and gold yellow fever vector [1][4][9][3]. Total magnification 25x under dissecting scope. Dr. Nels Grevstad Statistical and RStudio consultation Taylor Boyd, Shannon MacFadden , and Tyler Holmes Lab maintenance, peer review, and happy hour. By manipulating respiration rate, visual contrast, and surface temperature in different models, the relative importance of individual stimuli for female blood seekers can be quantified in the behavioral units observed in our original canopy biting bioassay. We predict the overall bite response will differ depending on the stimulus and to clarify if any statistically significant nasal preference exists for either Sabethes species. Female mosquitoes use a combination of thermotaxis, chemotaxis, and phototaxis to locate suitable blood hosts [5][6][8]. We observed lab populations of Sabethes species ( S. cyaneus and S. chloropterus ), displaying a strong preference for the nasal region of the human face. Mosquito Colonies and Rearing The MSU Denver colony is a secondary extension of the 1983 population established by R. G. Hancock and W. A. Foster at Ohio State University, from females collected in Maje Island in Lake Bayano , Panama [2]. Eggs : Individual oviposition into cup holes containing dechlorinated water and a small amount of larval water, no cohorts. Larvae : Eggs dumped into trays of dechlorinated water, fed every 6 days with powdered fish food. Incubator kept at 27 degrees Celsius and Light/Dark diel cycle 12L/12D. Pupae : Removed individually with plastic pipet into a large petri dish of dechlorinated water, covered in small foam pieces, then placed in cage for specific species. Imago(adult) : Emerge individually onto small foam pieces of petri while wings dry and unfurl. Fed organic honey on micro cellulose sponge rectangles, hung or attached inside cage by aluminum wiring. Sponges cleaned and refreshed with new honey every 6 days. Fig. 1M S.cyaneus cages Fig. 2M S. chloropterus cage Canopy Biting Bioassay Randomly select Sabethes species and population (Figs. 1M, 2M) . Secure host/model and treatment in canopy bioassay chamber (Figs. 3M, 4M, 5M, 6M) . Select actively probing/appetitive blood seeking females (Fig. 7M) . Release active specimens individually to canopy bioassay chamber (Fig. 8M) . Tally confirmed landing/bites/probing to designated facial regions over 25 minute period (Figs. 9M, 10M) . Remove host stimulus from bioassay chamber and recapture Sabethes females. Statistical Analysis 3x2 matrices: Chi squared Independence test and G test of Independence (0.05 significance level) used to interpret a total 240 individual responses to a live host by S. cyaneus and S. chloropterus, as well as 160 individual S.cyaneus responses to a foam model. 12 8 foam model trials for S. cyaneus only, 4 trials for each visual Methods & Materials Background Fig. 3M Fig. 4M Fig. 5M Fig. 6M Fig. 7M Fig. 8M Fig. 9M Fig. 10M Figs. 3M,4M, 5M Styro head with vinyl tubing in both nostrils. Fig 4M Fig 5M Fig 6M treatment with live host, nostrils plugged with Kimwipes and breathing out of vinyl tube. Figs. 7M, 8M show screening for active blood seekers and insertion to upper side of bioassay chamber. Figs. 9M,10M S.cyaneus biting nose on live Styro mouth exhaled respiration, volatile skin chemicals, and normal human skin surface temperature, to be a significantly appetitive stimulus combination for S. cyaneus and S. chloropterus S. chloropterus has a overall larger bite frequency than S. cyaneus , made more apparent in comparison of S. Cyaneus also has a significant nasal bite S. chloropterus , whom displays more generalized and frequent bites responses. Suppressed exhalation was highly significant in reducing overall biting frequency for both species, while S. cyaneus relative to S. chloropterus ( Figs 3R, 4R, 5R, 6R ). Aspects of surface temperature are important in combination with visual and respiratory cues, made apparent by the large relative lack of biting response of S. cyaneus in the foam model compared to the live model ( Figs 5R & 7R Styro visual contrast being highly significant to successfully identifying the nose on a host for S.cyaneus , provided by panty hoes significantly improved biting response. While tests are not tightly controlled for isolation of individual stimulus, like isolation of volatile chemicals and carbon dioxide gas passing in and out of the bioassay chamber from the surrounding lab, this experiment explored the interaction of thermal, visual, and chemical stimuli generally on the successful landing and probing of two Sabethes species. Results Live host Sabethes species comparison, an interspecific comparison of bite response when Fig. 3R Fig. 4R ). Species specific comparison of bite response when odor stimulus is manipulated: S. cyaneus Fig. 5R ), S. chloropterus (Fig. 6R) . Nasal respiration is a stronger trigger for S. cyaneus nasal preference than S. chloropterus , while it still does affect overall biting frequency in S. chloropterus . Fig. 5R Fig. 6R Fig. 3R Fig. 4R Fig. 7R There appears to be no statistically significant difference in bite response in S. cyaneus Styro Figs. 11R) nor the black contrast (Fig. 12R) Meaning the visual and exhaled respiration stimuli are not strong enough to trigger a strong appetitive response relative to a live host stimuli combination. However n asal preference is still exhibited by S. cyaneus foam model when no other bite response occurs. However considering these results in tandem with Fig. 8R Styro Fig. 8R Fig. 11R Fig. 12R Conclusion/Discussion Styro head testing with S. cyaneus shows no statistically significant difference in bite response trials were pooled ( Fig. 7R ). Meaning S. cyaneus had an overall low bite response to the foam model with or without respiration being manipulated. Results continued Styro comparing S. cyaneus bite response contrast over facial features shows a highly significant difference in bite response between the two visual model contrasts ( Fig. 8R ). Fig. 3R (live host) has a Chi Squared independence p value of 1.71E 01 and G Test independence p value of 0.169. All other p values are reported from Chi Squared results for live host test, while all foam model p values are for G Tests. The p values of both statistical tests match the magnitude and statistical significance as the Chi Squared stats, with the Fig. 3R exception. Fig. 4R (live host) has a p value of 2.71E 04. Fig. 5R (live host) has a p value of 3.63E 04. Fig. 6R (live host) has a p value of 7.30E 05. Fig. 7R ( S.cyaneus foam model) has a p value of 0.099. Fig. 8R (foam model) has a p value of 5.30E 05. Fig. 11R (foam model) has a p value of 0.345. Fig. 12R (foam model) has a p value of 0.127. Special Thanks 1. Galindo P, De Rodaniche E, and Trapido H. 1956. Experimental Transmission of Yellow Fever by Central American Species of Haemagogus and Sabethes chloropterus . ASTMH. 5(6): 1022 1031. 2. Hancock RG, Foster WA, and & Yee WL. 1990. Courtship behavior of the mosquito Sabethes cyaneus ( Diptera : Culicidae). Journal of Insect Behavior. 3(3): 401 416. 3. John Lane. 1953. Neotropical Culicidae, Volume 2. 1 st edition. DC: Entomological Society of Washington. 4. Karna AK, Sasha AR, Plante JA, Yun R, Vasilakis N, Weaver SC, Hansen IA, Hanley KA. 2018. Colonized Sabethes cyaneus, a Sylvatic New World Mosquito Species, Shows a Low Vector Competence for Zika Virus relative to Aedes aegypti. MDPI Viruses. 10(8):434. 5. Kawada H, Honda S, and Takagi. 2007. Comparative Laboratory Study on the Reaction of Aedes aegypti and Aedes albopictus to Different Attractive Cues in a Mosquito Trap. J. Med. Entomol . 44(3): 427 432. 6. Marston Bates. 1949. Natural History of Mosquitoes. 1 st Edition. Binghamton, New York (N.Y.): Vail Ballou Press, Inc. 7. McKenna RJ. Attraction of Seven Strains of Aedes aegypti to Man and Guinea Pig in the Laboratory. University of California Davis. 1973. 8. Van Breugel F, Riffell J, Fairhall A, Dickinson MH. 2015. Mosquitoes Use Vision to Associate Odor Plumes with Thermal Targets. Current Biology.25(16):2123 2129. 9. Zsemlye JL, Hancock RG, Foster WA. 2005. Analysis of a Complex Vertical Copulatory Courtship display in the Yellow Fever Vector Sabethes chloropterus . Med Vet Entomol . 19(3): 276 285. Citations