How to obtain a bloodmeal without being eaten by a host: the case of poultry red mite, Dermanyssus gallinae

Abstract.  The behavioural responses of the poultry red mite, Dermanyssus gallinae , to three host-related stimuli, vibration, heat and CO₂, are studied in light and dark. Although D. gallinae usually feeds on host-blood at night, it can also be day active after a few days of starvation. However, the immediate response of the mites to CO₂ in daylight is to freeze and remain motionless. Even with simultaneous presentation of an activating stimulus (heat), the mites freeze in response to CO₂. In the case of subsequent vibrations, they start moving but only for the duration of the vibrations. After 2 min, the freezing response disappears and the level of activity is significantly higher than for mites stimulated with vibrations alone. The freezing response is interpreted as a defence against being eaten by the host that apparently is close enough to breathe on the mites. At low-light intensities, where the birds are unable to see the mites, there is no freezing response, but only a synergistic effect of heat and vibration on the level of activity. The frequency of vibration most efficient in eliciting movement during the freezing response is found at 2 kHz with a threshold value of 35 µm s⁻¹ peak-peak, suggesting that D. gallinae is more sensitive to substrate-borne vibrations than some insects (e.g. honeybees) known to use vibrations for intraspecific communication.