Download Lecture 12 (Orthoptera)

Grasshoppers, crickets
and katydids
(EE, pp. 119-127)
Orthoptera
Common name: Grasshoppers, crickets and their
relatives (20,000 known world species (2.0%))
Derivation: Gk. orthos - straight; pteron - a wing
Size: Body length 5-155 mm
Metamorphosis: Incomplete (egg, nymph, adult)
Distribution: Worldwide but mostly in warm regions
Number of families: 28
Phylogeny of
Hexapoda
(from p. 52)
Orthoptera
Key Features
•
hind legs usually much larger and longer than other
legs and used for jumping
•
many species make sounds using hind legs and/or
front wings
•
characteristic ‘grasshopper’ shape with pronotum
extended down at each side
•
several species are serious crop threats
Rocky Mountain Locust
(12.5 trillion individuals)
http://www.sciencecases.org/locusts/locusts.asp
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
Common features:
- long, or very long, multi-segmented antennae
- mainly nocturnal and solitary
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
Common features:
- cryptically colored (brown or green) to mimic
dead or living leaves
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
Common features:
- in females, the ovipositor is always prominent
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
Common features:
- mostly herbivorous (plant eaters), but some are
partly or wholly predaceous
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
•
•
mormon crickets - a type of katydid
omnivorous - recent outbreaks
(1935-1938)
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
•
•
cave crickets - caves and burrows
saprophagous, predaceous
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
•
•
mole crickets - burrows
omnivorous
Ensifera
(katydids, true crickets, cave crickets, mole crickets)
•
Jerusalem crickets - also called niño de la tierra
(because of their large human-like head)
•
giant weta - from New Zealand
Caelifera
(grasshoppers, locusts, pygmy locusts, bush hoppers, bush locusts)
Common features:
- short antennae
- females never have prominent ovipositors
Caelifera
(grasshoppers, locusts, pygmy locusts, bush hoppers, bush locusts)
Common features:
- generally ground living, diurnal, & grass-feeding
- can be cryptically or warningly colored
The Locust is a musical group from San Diego, California, United
States known for their unique mix of grindcore speed and
aggression, complexity, and new wave weirdness
\m/
http://www.youtube.com/watch?v=2jGZJxnJk-4&feature=player_embedded
African desert locusts...
(how unusual was the 8th biblical plague?)
•
desert locusts can exist in two distinct phases,
either solitary or gregarious
•
outbreaks are cyclical
Why do they jump?
(an older name for the Orthoptera is “Saltatoria”)
•
•
•
jumping is an effective means of escape
enable insects to take to the air
powerful hind legs can be used to kick attackers two rows of spines run along the leg
Males like to sing
(songs, and the manner in which they are produced, are diverse)
•
•
•
used to attract females
also signals territory, aggression or alarm
Orthoptera sing at different times of the day...
- grasshoppers sing during the day
- katydids sing at night
- crickets sing during the day or at night
•
ensiferans (e.g. katydids, crickets) produce songs by
rubbing parts of their front wings together
•
caeliferans (grasshoppers) more varied
- rub inner face of hind femur against the edge of the tegmina (front wing)
- also use hind wing snapping and palp and/or mandible rubbing
Males like to sing
(ensifera rub their hind wings together - a file and scraper)
A male tettigoniid faces forward, displaying the sound-generating structures of the tegmina (forewings): a mirror or modified
wing cell that radiates sound produced by shocks from the passage of a scraper along a line of teeth (the file). The tegmina with
file and scraper visible, are also shown (above right) from beneath. The insect's ears are on its forelegs, each double eardrum
backed by an acoustic trachea that runs up the leg, swells into a horn-like internal chamber and finally opens on the thorax via
an acoustic spiracle. Sounds can arrive at both the front and the back of the tympana. (The acoustic tracheal system is drawn
as if the insect were transparent.) Drawing reprinted with permission from Morris 1998, copyright © 1998 Elsevier Science.
Males like to sing
(califerans like to rub their hind femur against the front wing)
a grasshopper’s tympanum
(or ear) is located on either
side of the first abdominal
segment
Cricket and Katydid songs
(singing insects of North America; by Thomas J. Walker)
http://entomology.ifas.ufl.edu/walker/buzz/a00samples.htm
Courtship
(varies from simple affairs to complex ‘wooing’)
•
•
the quality of sound that a male produces matters
•
some crickets can remove sperm from pervious
males (Truljalia hibinonis). The sperm is not wasted,
it is eaten!
being the last male to mate is helpful...sperm
operates on a last-in first-out basis
Courtship
(varies from simple affairs to complex ‘wooing’)
•
many ensiferans transfer sperm using a
spermatophore
-
an ampulla this contains the sperm
a spermatophylax contains a nuptial gift (holds nutrients, which are eaten)
Strange mating
(sagebrush crickets belonging to the genus Cyphoderris)
•
the female eats the male’s hind wings, and drinks
their hemolymph!
Mating in the Caelifera
(the male is general on top of the female)
•
eggs laid in the ground, in a pod