Four points along the pronota of Umbonia females were measured with laser vibrometry. Results from one individual show the body motion when the wave arrives from ahead of vs. behind the insect. From Miles et al. (2001).

Many small insects can find a vibration source on a plant. However, the mechanisms underlying their directional abilities are unclear because the time and amplitude cues used by larger organisms are not available. Two classes of mechanisms that are independent of body size could allow very small insects to locate a vibration source: (1) mechanical pre-processing that transforms minute time differences between front and back legs into direction-dependent differences in the motion of the front and back of the body (see figure); or (2) sequential sampling along a gradient. Amplitude gradients occur under some conditions on plants, and we are investigating the influence of amplitude changes on the insects’ turning behavior. We are also investigating how the whirling motion of plant stems changes along the search path of an insect homing in on a vibration source, and how such changes influence directional decisions.

Male-female duet of Tylopelta gibbera, showing the whine and pulses of an advertisement signal, and the mask produced by a rival.

Locating a signaling female is especially difficult for mate-searching Tylopelta gibbera males in the presence of a competitor, because males use special signals to interfere with duets, preventing the female from responding to rivals. We are studying how selection shapes the features of these disruptive signals.

Publications:

Gibson, J.S. & Cocroft, R.B. (in prep). Mate searching and directional accuracy in treehoppers.

Horisk, CS & Cocroft, RB. 2013. Animal signals: always influence, sometimes information. Pp. 259-280 in: Animal Communication Theory: Information and Influence (Stegmann, U, ed.). Oxford University Press.  (pdf)

Legendre, F, Marting, PR & Cocroft, RB. 2012. Competitive masking of vibrational signals during mate searching in a treehopper. Animal Behavior 83:361-368. (pdf)

Miles, RN, Cocroft, RB, Gibbons, C and Batt, D. 2001. A bending wave simulator for investigating directional vibration sensing in insects. Journal of the Acoustical Society of America 110:579-587. (pdf)

Cocroft, RB, Tieu, T, Hoy, RR & Miles, R. 2000. Mechanical directionality in the response to substrate vibration in a treehopper. Journal of Comparative Physiology 186: 695-705. (pdf)

Collaborations:

Dr. Ron Miles, Mechanical Engineering, Binghamton University

Dr. Quang Su, Mechanical Engineering, Binghamton University

Dr. Carol Miles, Biological Sciences, Binghamton University