Unformatted text preview: Making Sense of the World:
How Insects Use Their Senses
& Insect Communication Lecture Goals
• How do insects sense the world
• What are the tools of the insect
• Introduction to insect
communication Insect Nervous System, the Senses and
A. B. A. Side view of stylized insect body, nervous system is
blue. B. Dissected nervous system viewed from the top of
the insect. Note the highly segmented nature of the
nervous system. 1 How do insects sense the
world around them
•Vision (simple and compound
•M h i l senses
•taste Vision •Simple eyes or
→ do not sense color → sense differences in
light and dark •Found on top of the
head between the
compound eyes Vision See images at 100 frames/second (humans = 15 frames/second).
Fast flying insects evolved this system to cope with high speed
flight in complex environments. Sensitive to color (detects UV
light, but not the far red spectrum) 2 Mechanical Sensations: Touch Scanning electron
shows a single sensory
hair that acts as a touch
receptor Hairs on the insect
body act as touch
receptors. When the
insect touches an
object with the hair,
touches the hair, it
bends, deforming the
membrane at its
base which is
connected to a
nerve. A section of
such a hair is shown
on the right. --graphics
Alien Empire, p. 50 3 Mechanical Sensations: Touch
•Hairs serve as touch receptors.
•Touch receptors are used in
communication with other insects
and to sense the physical
•Special touch receptors are
sensitive to vibrations transmitted
through whatever surface the insect
is on, eg. planthoppers produce a
low frequency “song” that transmits
as vibrations through plant stems
and leaves (NOT AIRBORNE). Mechanical Sensations: Sound
•The perception of sound = perception of airborne
•Humans hear a limited range of frequencies (20 to 20,000
Hertz). Insects hear in the range of 1 to 100,000 Hertz
(although each species hears in a narrow range within this).
•Insect hearing involves a special touch receptor that is
sensitive to airborne vibrations.
•This touch receptor is a membrane attached to clusters of
special cells that connect to an auditory nerve. This nerve
translates vibrations into nerve impulses that are conducted
to the group of nerves in the insect head that we call the
brain. Mechanical Sensations: Sound
•We call the touch receptor for detecting
sound the insect ear. The exact position
of the ear varies with species, but may
be on the legs, thorax, wings or
--graphics from Alien Empire, p. 54 -- from Intro to Insect Biology and Diversity, p.
134 4 Mechanical Sensations: Sound
•Sound is key in the mating of many insects.
•Specificity may be determined via a match
between the female hearing range and the
sounds made by singing males of their own
•The male of each species has its own specific
song, so females of other species, even closely
related ones are effectively deaf to them.
•This system has the advantage of being
transmitted over considerable distance while
allowing communication to be very specific with
your own species. Chemical Senses:
Smell and Taste
•Insects have a highly sensitive sense of
•The antennae hold the principal organs of
•Scent is a very important means of
communication and the sensory structures
on the antennae are geared to detect
airborne molecules as well as those laid
down on a solid surface.
•Although they are very sensitive, insects
respond to a narrow range of scents that are
relevant to their behavior. Thus, chemical
communication can be very private and
useful over large distances.
•Insects use scent to communicate to
potential mates, warn members of their
species of danger and in social insects to
communicate about food, caste and colony
status. Chemical Senses:
Smell and Taste Multibranching of
the receptive area for
smell. 5 Chemical Senses:
Smell and Taste
•Chemicals for communication between insects of
the same species = pheromones
•Very small pheromone quantities, highly selective
sensors in the antennae = responses to relevant
•Versatile communication (mixtures and molecule
orientation = secure, species specific
Questions: How do pheromones and hormones
differ? What is meant by “relevant scents”? What is
meant by versatile communication? Chemical Senses:
Smell and Taste
•Taste sensors (on or near mouthparts
•How do these sensors help insects to
locate food plants?
•How and for what insects do taste
sensors benefit communication?
Questions: What is trophyllaxis? What
can humans learn from insect
communication? Even the smallest among
• Communication in the world of thrips
– Male Leks
– Territoriality 6 Summary
•Insects use vision, touch, sound and
chemistry to sense the world around them.
•These senses are important to their ability to
find mates, to defend themselves and to
interact within a colony when social.
•The sensory cues that a particular insect
species detects are often narrow, thus,
communication can be very species specific
and operate over relatively large distances. Questions to Answer from the
•What are pheromones and how do insects use them to find
mates? What kind of sense organs are used to detect
pheromones? What are the advantages to using a
pheromone in mate searching and recognition?
•What moth fine-tunes the system using pheromones and
finesound? Wh t i th advantage t adding a sound
d? What is the d
component to the communication?
•What example is given regarding use of sound in
communication? Why doesn’t this strategy disadvantage the
insect with regard to attracting predators?
•How does the jewel beetle use vision in identifying a mate?
How have humans interfered with this communication?
•How does the male walnut husk fly use touch in
communication? 7 ...
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This note was uploaded on 10/03/2009 for the course ENT 1 taught by Professor Ullman during the Fall '08 term at UC Davis.
- Fall '08