Hearing and acoustic interaction in mosquitoes

Warren, Ben (2011) Hearing and acoustic interaction in mosquitoes. Doctoral thesis (PhD), University of Sussex.

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Johnston, who discovered the mosquito auditory organ at the base of the
antennae 150 years ago, speculated that audition was involved in mating
behaviour. Indeed, the Johnston’s organ (JO) is now known to detect the whine
of flying mosquitoes. Analysis of sound recordings of flight tones from tethered,
flying, mosquitoes revealed that opposite-sex pairs, when within their acoustic
near-fields, attempt to frequency-match the harmonic components of their flighttones.
Same-sex pairs actively avoid frequency-matching. Mosquitoes of the
species Toxorhynchites brevipalpis, where the flight-tone frequencies of males
and females are similar, attempt to match the fundamental frequency of their
flight-tones. Haemophilic, vector-carrying mosquitoes Culex quinquefasciatus
and Anopheles gambiae ss, where the fundamental frequency of the male flight
tone is about 1.5 times that of the female, frequency-match harmonic
components of their flight tones. Usually the male’s 1st harmonic with the 2nd
harmonic of the female flight-tone. In Burkina Faso, where two morphologically
similar molecular forms aggregate in the same swarms but rarely hybridise,
frequency-matching of flight-tones may perform a pre-mating barrier and a form
of subspecies recognition. We discovered that frequency-matching occurred
significantly more frequently between same-form male-female pairs of flying,
tethered mosquitoes, than when each member of the pair was of a different
molecular form. The bandwidth and tuning of sound-evoked flagellum vibrations
and the JO’s electrical responses to this mechanical input were measured using
laser interferometry and extracellular electrodes, respectively. For the first time
we showed that distortion products, recorded from the flagellum and JO, could
provide the neural basis for frequency-matching at frequencies beyond the
range of the JO’s electrical responses. We also discovered that spontaneous
oscillations of the antennae are produced by physiologically-sensitive
mosquitoes. Through temperature-control and injection of pharmacological
agents into the JO, evidence is presented advocating dynein as the molecular
motor responsible for powering these oscillations.

Item Type: Thesis (Doctoral)
Schools and Departments: School of Life Sciences > Biochemistry
Subjects: Q Science > QL Zoology
Depositing User: Library Cataloguing
Date Deposited: 13 Jun 2011 13:38
Last Modified: 14 Aug 2015 14:56
URI: http://sro.sussex.ac.uk/id/eprint/6946

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