Sugar feeding patterns of New York Aedes albopictus mosquitoes are affected by environmental dryness, flowers, and host seeking

Background Sugar feeding is an important behavior which may determine vector potential of mosquitoes. Sugar meals can reduce blood feeding frequency, enhance survival, and decrease fecundity, as well as provide energetic reserves to fuel energy intensive behaviors such as mating and host seeking. Sugar feeding behavior also can be harnessed for vector control (e.g. attractive toxic sugar baits). Few studies have addressed sugar feeding of Aedes albopictus, a vector of arboviruses of public health importance, including dengue and Zika viruses. To address this knowledge gap, we assessed sugar feeding patterns of Ae. albopictus for the first time in its invasive northeastern USA range. Methodology/ Principal Findings Using the cold anthrone fructose assay with robust sample sizes, we demonstrated that a large percentage of both male (49.6%) and female (41.8%) Ae. albopictus fed on plant or homopteran derived sugar sources within 24 hrs of capture. Our results suggest that sugar feeding behavior increases when environmental conditions are dry and may vary by behavioral status (host seeking vs. resting). Furthermore, mosquitoes collected on properties with flowers (>3 blooms) had higher fructose concentrations compared to those collected from properties with few to no flowers (0-3). Conclusions/Significance Our results provide the first evidence of Ae. albopictus sugar feeding behavior in the Northeastern US and reveal relatively high rates of sugar feeding. These results suggest the potential success for regional deployment of toxic sugar baits. In addition, we demonstrate the impact of several environmental and mosquito parameters (environmental dryness, presence of flowers, host seeking status, and sex) on sugar feeding. Placing sugar feeding behavior in the context of these environmental and mosquito parameters provides further insight into spatiotemporal dynamics of feeding behavior for Ae. albopictus, and in turn, provides information for evidence-based control decisions.

70 studies indicated that season, habitat, and sugar availability might be important, as well as 71 temperature and humidity [16,23].

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In Israel, the percent of sugar positive Ae. albopictus varied by season and habitat type 73 (irrigated garden versus dry wasteland), ranging from 41.4% (summer) to 74.1% (fall) at a 74 wasteland site [23]. However, this study was performed with an abbreviated cold anthrone assay, 75 using visual detection of color change, instead of precise measurement of fructose concentration 76 using established methods [23]. A subsequent study evaluating Ae. albopictus visitation to sugar 77 sources reported attraction to a subset of tested ornamental flowers, wildflowers, damaged carob 78 seed pods and fruits, but no attraction was detected to honeydew coated plants [33]. Working 79 with releases of high generation laboratory colony males in northern Italy, Bellini et al. (2014) 80 utilized an abbreviated cold anthrone assay to detect higher sugar feeding rates for released 81 males at sites with sucrose feeding stations compared to control sites and a positive correlation 82 with temperature and negative correlation with humidity [16]. In Florida, where the only other 83 US study was conducted, Ae. albopictus fructose concentration did not vary significantly with 84 plant species utilized as resting habitat; unfortunately, no analyses were conducted to determine 85 the proportion sugar fed [32]. Another limitation of these studies was the lack of established 86 baseline fructose levels, leading to the potential misidentification of larval nutrients as adult 87 sugar meals.

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The current knowledge of Ae. albopictus sugar feeding in the field primarily stems from 89 these four studies in Israel, Italy, and Florida. Additionally, assessments of ATSBs for Ae.  184 mosquitoes were removed per day. Fructose concentration was measured as described above. 185 The assumption of constant variance was not met, so mean fructose concentrations were 186 compared to concentration before feeding using the non-parametric Kruskal-Wallis test followed 187 by a Dunn's multiple comparisons test with Benjamini-Hochberg correction (reported as P adj ).    398 blood feeding may increase the public health impact of ATSBs by concentrating control pressure 399 before the point of pathogen acquisition or transmission.

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As the ability to detect DNA from mosquito plant meals improves, future studies could 401 explore sugar feeding with greater resolution than the cold anthrone test affords. Next-generation 402 sequencing has been employed to successfully identify plant meals of mosquitoes and other 403 blood feeding Diptera [62,63]. Additional studies of Ae. albopictus plant meal origin would be 404 beneficial in ATSB lure design optimization. However, results of these analyses must be 405 interpreted with caution as they may bias towards non-nectar sugar sources that are more likely 406 to be detected via DNA-based analyses due to minimal DNA content of nectar.

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Our results demonstrate, for the first time, sugar feeding patterns by temperate 408 populations of Ae. albopictus in the United States. This is only the fourth field study on this 409 important mosquito behavior and provides us with insights into conditions that might influence