Sound production in bark and ambrosia beetles

© 2019, © 2019 Informa UK Limited, trading as Taylor & Francis Group. Bark and ambrosia beetles and pinhole borers (Coleoptera: Curculionidae: Scolytinae and Platypodinae) are two subfamilies of weevils that use acoustic communication within plant tissue. These insects transmit and detect sound in a medium that is neither air nor water and they are among the smallest animals with sound-producing organs. Nevertheless, their sound production is sorely understudied, mostly due to the difficulties associated with acoustically monitoring individuals inside plants. We analysed the stridulatory sounds from 55 bark and ambrosia beetle species within 15 subtribes collected in four countries, making this the largest acoustic dataset of these taxa to date. We characterised and compared the amplitude and spectro-temporal parameters of the distress airborne signals produced by the beetles, in conjunction with phenology and life history data. Sound production was present in 33% of the collected species, of which 60% of these sounds had not been previously reported. Depending on species, either both sexes stridulated or only one. Some species had calls with different acoustic morphotypes (one, two, or three notes), and when both sexes stridulated, sounds generally differed. Our data suggest that type of mating system and size play an important role in determining the acoustic communicatory capacity of most species

Coulomb effects in granular materials at not very low temperatures

We consider effects of Coulomb interaction in a granular normal metal at not very low temperatures suppressing weak localization effects. In this limit calculations with the initial electron Hamiltonian are reduced to integrations over a phase variable with an effective action, which can be considered as a bosonization for the granular metal. Conditions of the applicability of the effective action are considered in detail and importance of winding numbers for the phase variables is emphasized. Explicit calculations are carried out for the conductivity and the tunneling density of states in the limits of large $g\gg 1$ and small $g\ll 1$ tunnelling conductances. It is demonstrated for any dimension of the array of the grains that at small $g$ the conductivity and the tunnelling density of states decay with temperature exponentially. At large $g$ the conductivity also decays with decreasing the temparature and its temperature dependence is logarithmic independent of dimensionality and presence of a magnetic field. The tunnelling density of states for $g\gg 1$ is anomalous in any dimension but the anomaly is stronger than logarithmic in low dimensions and is similar to that for disordered systems. The formulae derived are compared with existing experiments. The logarithmic behavior of the conductivity at large $g$ obtained in our model can explain numerous experiments on systems with a granular structure including some high $T_{c}$ materials.Comment: 30 page