Download Lecture 15 (Bugs)(handout)

Bugs, aphids & hoppers,
oh my!
(EE, pp. 153-166)
Phylogeny of
Hexapoda
(from p. 52)
Hemiptera
Hemiptera
Common name: Bugs, aphids, hoppers, etc. (82,000
known world species (8.2%))
Derivation: Gk. hemi - half; pteron - a wing
Size: Body length 1-100 mm; mostly under 50 mm
Metamorphosis: Incomplete (egg, nymph, adult)
Distribution: Worldwide
Number of families: 134
Key Features
•
•
very abundant and widespread
•
stink glands and sound producing organs
sometimes present
•
many species are significant plant pests and some
transmit human and animal diseases
•
the fifth largest order
mouthparts forming a piercing/sucking beak or
rostrum for liquid feeding
They are everywhere!
(terrestrial habitats, fresh water and even out to sea)
•
the largest and most
successful of the
exopterygote
orders
•
recent estimates
suggest more than
105,000 species of
bugs are not
described - based
on work in the
tropical rain forests
of Indonesia
Halobates - often found hundreds of miles from land
Suborders of Hemiptera
(used to be split into two large groups - Heteroptera and Homoptera)
Suborder
Number of families
Feeding habits
Coleorrhyncha
1 (Peloridiidae)
Herbivorous on mosses and liverworts
Heteroptera
73
Herbivorous, predacious, parasitic
Auchenorrhyncha
31
Herbivorous
Sternorrhyncha
29
Herbivorous
Suborder Sternorrhyncha
(the basal hemipteran suborder - all herbivorous)
potato/tomato psyllid
silverleaf whiteflies
pea aphid
scale insect
Suborder Auchenorrhyncha
(all herbivorous)
treehopper
froghopper
leafhopper
planthopper
some cool planthoppers - lantern bugs
Suborder Coleorrhyncha
(contains a single family - found only in the southern hemisphere)
•
•
small, flattened and cryptically
colored - live in saturated moss at
the base of Nothofagus trees
Likely originated in Antarctica and
were in existence prior to the
break-up of Gondwana
(supercontinent that included the
landmasses in today’s southern
hemisphere)
planthopper
Suborder Heteroptera
(the true bugs - includes herbivorous and predacious members)
water boatman (corixid)
tarnished plant bug (mirid)
bed bug (cimicid)
Suborder Heteroptera
(this is the largest suborder - it is very diverse)
water strider (gerrid)
giant water bug (belostomatid)
stink bug (pentatomid)
shield bug
leaf or plant bug
(mirid)
stilt bug (berytid)
hammerhead bug (geocorid)
lace bug (tingid)
The perfect suckers
(all bugs possess piercing, sucking mouthparts that form a rostrum (long beak))
Heteroptera
Sternorrhyncha
In Sternorrhyncha (iii) and Auchenorryhncha (ii) the
rostrum is permanently directed backwards
Auchenorryhncha
uchenorryhncha
How the rostrum works
(the bug rostrum is similar throughout the order)
How to feed on plants
(how does a bug reach phloem or xylem?)
•
stylets work
through plant cells
•
stylets protected by
a salivary sheath
Filter chambers
(some sap suckers have a modified gut - deals with excessive fluids)
two-linned spittlebug (cercopid)
Feeding on low quality food
(some bugs rely on microorganisms to provide essential nutrients)
•
generally bacteria
contained within
special bodies in the
haemoceol or inside
lumen of the midgut
•
in aphids, bacteria in
specialized cells
called mycetocytes
•
provide nitrogen,
vitamins and some
lipids
Fig. 1. (Left) Pea aphids on a broad bean seedling. (Right) In the
aphid body, symbiotic bacteria with important biological roles
are harbored in specialized cells. Buchnera (green) is essential
for survival and reproduction of the host aphid. Serratia (red)
confers a resistance to high temperature on the host aphid, and
can compensate for the essential biological roles of Buchnera.
Blue shows aphid’s nuclei.
Predatory bugs
(some are active hunters, others ambush their prey)
Practicing defense
(many heteropterans produce noxious or repellant organic compounds)
Practicing defense
(many heteropterans advertise their defenses using bright colors)
Bugs and ants
(many bugs have evolved mutualistic relationships with ants)
Sociality in bugs
(usually only think of the Hymenoptera and Isoptera as being social)
•
first instar nymphs
of some aphid
species serve as
colony defenders
•
attack invaders with
specialized horns or
with their
mouthparts
•
soldiers usually
don’t live past the
first instar
Reproduction in bugs
(most bugs reproduce bisexually, but some are hermaphrodites)
•
around 10% of aphid
species have
complex life cycles
involving sexual and
asexual forms
•
involves alternations
of generations
between two
unrelated host
plants (one woody
and one
herbaceous)
Finding mates
(males can sing, some talk through mechanical vibrations)
Periodic cicadas
(time from hatching to adult emergence is either 13 or 17 years)
Bloomington, IN (2004)
Paternal care
(males sometimes protect or even carry the eggs)
Bugs as human pests
(some bugs feed on blood and are vectors of human disease)
•
bed bugs have a long
history of
association with
people
•
feed at night, hide in
bedding, mattresses
or cracks in floors
and walls during day
•
hosts located by
body temperature,
odors and CO2
kissing bugs are a vector for Chagas disease - 18
million people affected (causes death in children)
Bugs as human pests
(some auchenorrhynchan and sternorrhynchan are crop pests)
soybean aphid
causes “sticky cotton”
bugs are often vectors for many plant diseases