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Investigations of mosquito oviposition cues and a pitcher-plant community
Ombrotrophic bogs are fragile habitats containing unique flora and fauna. My investigations focused on the carnivorous pitcher plant, Sarracenia purpurea L. The leaves of the pitcher plant trap insects which the plant digests primarily to obtain nitrogen. The leaves hold water that also provides a habitat for two symbiotic insect species, the pitcher plant mosquito, Wyeomyia smithii, and the pitcher plant midge, Metriocnemus knabi. The pitcher plant resident insects use trapped insects for nutrition and may aid the plant by processing the trapped insects into smaller particles. I investigated female oviposition behavior of female Aedes triseriatus mosquitoes when given the choice among large and small artificial containers of different colors. Large containers were selected significantly (t = 3.5, df = 8, P = 0.008) more often (72% of the trials) than smaller containers (44% of the time). Black and green containers were selected most often, while white containers were selected significantly less often (ANOVA: F = 3.8, df = 17, P = 0.047). Results indicate that Ae. Triseriatus could use pitcher plant leaves for oviposition. I assessed the insect community at Brighton Bog, in New York State using double sided yellow sticky cards to capture insects over a 24 hour period. These traps revealed available prey to be dominated by minute insects (<10 >mm), especially dipterans. Pitcher plant leaves provide habitat for the midge and mosquito larvae which also use the trapped insects for nutrition. No other mosquito species has been reported to use this resource and I performed a series of experiments to investigate exclusion of foreign mosquitoes. I introduced early stage larvae of Aedes triseriatus to pitchers containing midge larvae, Wy. smithii larvae or no other insect larvae. Results suggest that the midge eliminates foreign mosquito larvae from the leaves of the pitcher plant. Across 90 trials, Ae. triseriatus was eliminated from 68% of pitchers with midges within the first hour. During this investigation, near drought conditions provided the opportunity to test whether dry pitchers, once replenished with water, would become occupied by mosquitoes or midges. After the addition of water, both Wy. smithii and M. knabi were observed, but no foreign mosquitoes were found. The potential for draught resistant eggs of any species was investigated by collecting dry pitchers and re-hydrating them, but no larvae were observed. These results suggest that adults of the symbiotic species are present in the bog environment while other mosquitoes may not be present. The results of my investigations reveal insights to eastern treehole mosquito oviposition that can aid in management of this species that can vector human and animal diseases. The results from the study of drought on pitcher plants and their insect community reveal that the organisms are likely adapted for occasional droughts. However, large perturbations in weather associated with climate change could reduce the ability of pitcher plants to acquire nutrients via predation and eliminate their obligate insects which may further limit nutrition of these highly adapted plants.
Torrisi, Gary Joseph, "Investigations of mosquito oviposition cues and a pitcher-plant community" (2013). ETD collection for University of Nebraska - Lincoln. AAI3557440.