Pollinators use their sense of smell to locate flowers from long distances, but little is known about how they are able to discriminate their target odor from a mélange of other natural and anthropogenic odors. Here, we measured the plume from Datura wrightii flowers, a nectar resource for Manduca sexta moths, and show that the scent was dynamic and rapidly embedded among background odors. The moth's ability to track the odor was dependent on the background and odor frequency. By influencing the balance of excitation and inhibition in the antennal lobe, background odors altered the neuronal representation of the target odor and the ability of the moth to track the plume. These results show that the mix of odors present in the environment influences the pollinator's olfactory ability.

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IMPORTANCE Azithromycin has been hypothesized to have activity against SARS-CoV-2.OBJECTIVE To determine whether oral azithromycin in outpatients with SARS-CoV-2 infection leads to absence of self-reported COVID-19 symptoms at day 14. DESIGN, SETTING, AND PARTICIPANTS Randomized clinical trial of azithromycin vs matching placebo conducted from May 2020 through March 2021. Outpatients from the US were enrolled remotely via internet-based surveys and followed up for 21 days. Eligible participants had a positive SARS-CoV-2 diagnostic test result (nucleic acid amplification or antigen) within 7 days prior to enrollment, were aged 18 years or older, and were not hospitalized at the time of enrollment. Among 604 individuals screened, 297 were ineligible, 44 refused participation, and 263 were enrolled. Participants, investigators, and study staff were masked to treatment randomization.INTERVENTIONS Participants were randomized in a 2:1 fashion to a single oral 1.2-g dose of azithromycin (n = 171) or matching placebo (n = 92). MAIN OUTCOMES AND MEASURESThe primary outcome was absence of self-reported COVID-19 symptoms at day 14. There were 23 secondary clinical end points, including all-cause hospitalization at day 21. RESULTS Among 263 participants who were randomized (median age, 43 years; 174 [66%] women; 57% non-Hispanic White and 29% Latinx/Hispanic), 76% completed the trial. The trial was terminated by the data and safety monitoring committee for futility after the interim analysis. At day 14, there was no significant difference in proportion of participants who were symptom free (azithromycin: 50%; placebo: 50%; prevalence difference, 0%; 95% CI, −14% to 15%; P > .99). Of 23 prespecified secondary clinical end points, 18 showed no significant difference. By day 21, 5 participants in the azithromycin group had been hospitalized compared with 0 in the placebo group (prevalence difference, 4%; 95% CI, −1% to 9%; P = .16).CONCLUSIONS AND RELEVANCE Among outpatients with SARS-CoV-2 infection, treatment with a single dose of azithromycin compared with placebo did not result in greater likelihood of being symptom free at day 14. These findings do not support the routine use of azithromycin for outpatient SARS-CoV-2 infection.

Flying insects rely on the integration of feedback signals from multiple sensory modalities. Thus, in addition to the visual input, mechanosensory information from antennae is crucial for stable flight in the hawkmoth Manduca sexta. However, the nature of compensatory reflexes mediated by mechanoreceptors on the antennae is unknown. In this study we describe an abdominal flexion response mediated by the antennal mechanosensory input during mechanical body rotations. Such reflexive abdominal motions lead to shifts in the animal's center of mass, and therefore changes in flight trajectory. Moths respond with abdominal flexion both to visual and mechanical rotations, but the mechanical response depends on the presence of the mass of the flagellum. In addition, the mechanically mediated flexion response is about 200° out of phase with the visual response and adds linearly to it. Phase-shifting feedback signals in such a manner can lead to a more stable behavioral output response when the animal is faced with turbulent perturbations to the flight path.

A pair of antagonistic thermoreceptive cells is associated with each of two peg-in-pit sensilla located on the antennal tip of Aedes aegypti. One, the warm cell, responds to rapid warming with a sudden increase in the rate of discharge. The other, a cold cell, responds to rapid cooling with a sudden increase in the discharge rate. When temperature changes are provided by oscillating changes in the convective heat contained in the stimulating air stream, the oscillating discharge rates of both cell types are in advance of the oscillations in temperature and slightly behind the oscillations in the rate of temperature change. Analysis of these phase relationships shows that both cell types respond not only to the actual temperature at particular instance in time (instantaneous temperature) but also to the rate with which temperature changes. Individual responses are therefore ambiguous and signal tendencies rather than precise instantaneous values. When the temperature oscillations are delivered by changes in radiation power, however, the oscillating discharge rates of the warm and cold cells are in step with the oscillations in temperature. Here, individual responses signal instantaneous values of temperature rather than tendencies. The power of radiant heat required to modulate the discharge rates is relatively high, suggesting that infrared radiation is not a significant cue in distant host location.

We evaluated the effect of systemic antibiotics (azithromycin, amoxicillin, cotrimoxazole, or placebo) on the gut resistome in children aged 6 to 59 months. Azithromycin and cotrimoxazole led to an increase in macrolide and sulfonamide resistance determinants. Resistome expansion can be induced with a single course of antibiotics.