Fruitless mutant male mosquitoes gain attraction to human odor
Authors: Maria Elena De Obaldia
Margaret Herre
Ricarda K von Heynitz
Takeshi Morita
Leslie B Vosshall
Yael N Tsitohay
Nipun S Basrur
Journal: eLife (2020)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: Aedes aegypti; CRISPR-Cas9; behavior; genetics; genomics
Affiliations: Laboratory of Neurogenetics and Behavior, The Rockefeller University, New York, United States

Abstract:  The Aedesaegypti mosquito shows extreme sexual dimorphism in feeding. Only females are attracted to and obtain a blood-meal from humans, which they use to stimulate egg production. The fruitless gene is sex-specifically spliced and encodes a BTB zinc-finger transcription factor proposed to be a master regulator of male courtship and mating behavior across insects. We generated fruitless mutant mosquitoes and showed that males failed to mate, confirming the ancestral function of this gene in male sexual behavior. Remarkably, fruitless males also gain strong attraction to a live human host, a behavior that wild-type males never display, suggesting that male mosquitoes possess the central or peripheral neural circuits required to host-seek and that removing fruitless reveals this latent behavior in males. Our results highlight an unexpected repurposing of a master regulator of male-specific sexual behavior to control one module of female-specific blood-feeding behavior in a deadly vector of infectious diseases. 

Retracted: No

PubPeer comments:
 Readers should become aware of a recent preprint entitled Strong attraction of male mosquitoes (Aedes aegypti) to humans that calls into question part of the conclusions by Basrur et al., 2020 study. These new experiments demonstrate attraction of male Aedes aegypti to humans, in direct contrast to the claim by Basrur et al. (2020) that only female mosquitoes host-seek. https: www.biorxiv.org content 10.1101 2021.05.24.445527v2 From the Abstract: Female Aedes aegypti mosquitoes integrate multiple sensory cues to locate human hosts for blood meals. While male mosquitoes do not blood feed, male Ae. aegypti swarm around and land on humans in nature. Basrur et al. (2020) generated male Aedes aegypti lacking the fruitless gene and discovered that they gained strong attraction to humans, similar to female mosquitoes. The authors assume that host-seeking is a female-specific trait, which they confirmed through experiments. However, all experiments were performed under confined laboratory conditions which appear to inhibit swarming behavior. We used semi-field experiments to demonstrate robust attraction of male Ae. aegypti to humans. Human-baited traps captured up to 25% of released males within 15 min, whereas control traps without humans as bait failed to capture males. Rapid attraction to humans was further demonstrated through videography. Males swarmed around and landed on human subjects, with no activity recorded in paired unbaited controls. The absence of female Ae. aegypti in these experiments rules out a hypothesis by Basrur et al. (2020) that males are attracted not to the human, but to host-seeking females near humans. Finally, we confirm the lack of male attraction to humans in small laboratory cages, even when using recently field-collected males. Our direct observations of male mosquito attraction to humans refute a key assumption of Basrur et al. (2020) and raise questions around conditions under which fruitless prevents male host-seeking. Male mosquito attraction to humans is likely to be important for mating success in wild populations and its basis should be further explored. , 
 An updated version of the preprint was posted today. New title: Comment on u2018Fruitless mutant male mosquitoes gain attraction to human odor https: www.biorxiv.org content 10.1101 2021.05.24.445527v2 ,