Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid's scent and the balance of excitation and inhibition in the mosquito's antennal lobe (AL). The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species-not visited by mosquitoesemit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to N,N-diethylmeta-toluamide (DEET), a mosquito repellent. Lateral inhibition between these 2 glomeruli reflects the level of attraction to the orchid scents. Whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door toward understanding the neural basis of mosquito nectar-seeking behaviors.Platanthera | mosquitoes | Aedes aegypti | olfaction | nectar M osquitoes are important vectors of disease, such as dengue, malaria, or Zika, and are considered one of the deadliest animal on earth (1); for this reason, research has largely focused on mosquito-host interactions, and in particular, the mosquito's sensory responses to those hosts (2-5). Nectar feeding is one such aspect of mosquito sensory biology that has received comparatively less attention, despite being an excellent system in which to probe the neural bases of behavior (6). For instance, nectar and sugar feeding is critically important for both male and female mosquitoes, serving to increase their lifespan, survival rate, and reproduction, and for males, it is required for survival (6, 7).Mosquitoes are attracted to, and feed on, a variety of plant nectar sources, including those from flowers (8)(9)(10)(11)(12). Although most examples of mosquito-plant interactions have shown that mosquitoes contribute little in reproductive services to the plant (13), there are examples of mosquitoes being potential pollinators (9, 10, 14-17). However, few studies have identified the floral cues that serve to attract and mediate these decisions by the mosquitoes and how these behaviors influence pollination.The association between the Platanthera obtusata orchid and Aedes mosquitoes is one of the few examples that shows mosquitoes as effective pollinators (14-17) and thus provides investigators a unique opportunity to identify the sensory mechanisms th...

Abstract. We present an electrospray ion source coupled to an orthogonal continuous-flow atmospheric pressure chemical ionization region. The source can generate intense and stable currents of several specific reagent ions using a range of salt solutions prepared in methanol, thereby providing both an alternative to more common radioactive ion sources and allowing for the generation of reagent ions that are not available in current chemical ionization mass spectrometry (CIMS) techniques, such as alkaline cations. We couple the orthogonal electrospray chemical ionization (ESCI) source to a high-resolution time-of-flight mass spectrometer (HRToF-MS), and assess instrument performance through calibrations using nitric acid (HNO 3 ), formic acid (HCOOH), and isoprene epoxydiol (trans-β-IEPOX) gas standards, and through measurements of oxidized organic compounds formed from ozonolysis of α-pinene in a continuous-flow reaction chamber. When using iodide as the reagent ion, the HR-ToF-ESCIMS prototype has a sensitivity of 11, 2.4, and 10 cps pptv −1 per million counts per second (cps) of reagent ions and a detection limit (3σ , 5 s averaging) of 4.9, 12.5, and 1.4 pptv to HNO 3 , HCOOH, and IEPOX, respectively. These values are comparable to those obtained using an iodide-adduct HR-ToF-CIMS with a radioactive ion source and low-pressure ion-molecule reaction region. Applications to the α-pinene ozonolysis system demonstrates that HRToF-ESCIMS can generate multiple reagent ions (e.g., I − , NO − 3 , acetate, Li + , Na + , K + , and NH + 4 ) having different selectivity to provide a comprehensive molecular description of a complex organic system.

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Coagulase-negative staphylococci (CoNS) are frequently commensal bacteria that rarely cause disease in mammals. Staphylococcus lugdunensis is an exceptional CoNS that causes disease in humans similar to virulent Staphylococcus aureus , but the factors that enhance the virulence of this bacterium remain ill defined. Here, we used random transposon insertion mutagenesis to identify the agr quorum sensing system as a regulator of hemolysins in S. lugdunensis .