Frequency (Hz)

FIGURE 12.7. Sensitivity curves for (A) tympanal organ of Locusta, (B) cercal hairs of Gryllus, and (C) human ear. [After V. G. Dethier, 1953, Mechanoreception, in: Insect Physiology (K. D. Roeder, ed.). Copyright © 1953 John Wiley and Sons, Inc. Reprinted by permission of John Wiley and Sons, Inc.]

to frequencies in the range of 15-60 kHz, which comes within the frequency range of the sounds uttered by the bats as they echolocate. A moth's response varies according to the intensity of the sound. At low intensity (i.e., when the bat is 30 m or more distant) a moth moves away from the sound. At high intensity, a moth takes more striking action, flying an erratic course, or dropping to the ground. In a few species of Lepidoptera ultrasound is used in sexual communication (Spangler, 1988).

The phenomenon of acoustic parasitism was firstreported by Cade (1975) who observed that gravid females of the tachinid fly Ormia ochracea locate their host, the field cricket Gryllus integer, by homing in on the male cricket's mating call. Since then, other tachinids and some sarcophagid flies that parasitize cicadas have been shown to use the same strategy for host location. On locating a cricket, the fly larviposits on or near it. The tachinid's ears are typical tympanal organs, located on the prosternum, and are most sensitive in the range of 4-6 kHz (the dominant frequency of the cricket's song is 4.8 kHz). Interestingly, in these nocturnally active flies males also have tympanal organs though these are insensitive to frequencies around 5 kHz. However, the ears of both male and female flies are sensitive to ultrasonic sounds (20-60 kHz). It is thought that this range of sensitivity is related to the flies' need to detect and avoid becoming prey for insectivorous bats.

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

Get My Free Ebook

Post a comment