Transcript Topic 12 Arthropods 2

Subphylum Myriapoda

Myriapoda (Greek “many feet”) includes two
major groups the Chilopoda (centipedes) and
Diplopoda (millipedes) as well as two smaller
groups the Symphyla and the Pauropoda, both
of which are small soil-dwelling organisms.

Myriapods have a head with simple eyes and a
segmented trunk which carries paired
appendages, one per segment in centipedes
and in most segments two in millipedes.
Subphylum Myriapoda
 On
the head myriapods have one pair of
antennae, mandibles and one or two pairs
of maxillae or feeding appendages.
 Walking
legs are found on the abdominal
segments.
Class Chilopoda

There are about 3,000 described species and an
estimated 8,000 worldwide.

Centipedes (from the Latin for hundred feet) differ from
millipedes in that each segment bears only one pair of
appendages. They always have an odd number of pairs of
legs.

Distribution is worldwide ranging from Tropics to the Arctic
Circle. Require moist microhabitats because the cuticle is
not waxy and so is not watertight.

Respiration is primarily via a tracheal system, but a few
species exchange gases across the body surface.
Class Chilopoda
 Centipedes
range in size from a few
millimeters long to 30cm (the Amazonian
Giant Centipede), which makes them
some of the largest terrestrial invertebrate
predators and they are a significant
element of the predatory biomass in many
invertebrate communities.
http://www.google.com/imgres?imgurl=http://www.cutehomepets.com/wpcontent/uploads/2011/01/giant-centipede.jpg
Class Chilopoda

The first pair of appendages have been modified
into poison fangs (forcipules), which they use to
kill prey.

Centipedes are active predators that hunt in leaf
litter, under logs and in similar damp, dark
places for prey.

The body is dorsoventrally flattened, which
probably allows the centipede to squeeze into
small spaces in pursuit of prey.
Figure 20.01
12.32B
Class Diplopoda

Diplopods are commonly called millipedes (Latin
“thousand feet”). Most have 36-400 legs with
750 being the maximum.

They have a distinctively cylindrical body and
this coupled with the fact that most segments
have two pairs of legs (all but the first four
thoracic segments, which have one pair each)
makes millipedes hard to misidentify.
Class Diplopoda

There are about 10,000 described species and
they occur worldwide.

Millipedes range from a few millimeters in length
up to 38 cm (the African giant Millipede).

The largest terrestrial invertebrate ever was a
2.6 meter long millipede Anopleura from the
Carboniferous (340-280 mya).
Figure 20.02
12.33
Class Diplopoda

Millipedes because of their large number of legs
move in a distinctive flowing manner, but are
generally less active than centipedes. Slow
moving.

Most millipedes are scavengers that feed on
decaying detritus and plant material which they
consume using large chewing mandibles.

They prefer moist, dark places.
Class Diplopoda
 The
primary means of defense is to curl up
into a tight ball protecting their vulnerable
underside.
 However,
by toxins
many species are also protected
 Millipede
mating clip
 http://www.youtube.com/watch?v=emvTpB
BfUwk
 Hunting
centipede clip
 http://www.youtube.com/watch?v=UROVf
mY3NTA
Subphylum Crustacea

The crustaceans are another very large group of
arthropods with more then 67,000 described
species.

The group includes crabs, lobsters, shrimp,
copepods, pill bugs, barnacles, krill, and
crayfish.

The crustaceans are the only arthropod group
whose members are almost all aquatic, and
mostly marine.
Crustaceans
 The
crustaceans are the only arthropods
with two pairs of antennae.
 They
also have a diverse array or other
appendages specialized for different tasks.
Lobster appendages
 For
example, in lobsters on the head there
are two pairs of antennae, a pair of
mandibles for eating and two pairs of other
feeding appendages called maxillae.
 These
are followed by three pairs of
maxillipeds, which are food handling
appendages, mounted on the thorax.
Figure 19.02b
12.16B
Lobster appendages

After the maxillipeds, come the five pairs of
walking legs, the first of which are modified in
many cases into large clawed chelipeds.

Abdominal appendages are modified for
swimming. These swimmerets are used for
locomotion, but in males the first pair are
modified for copulation. The last pair of
appendages (uropods) are wide and assist the
animal in moving backwards quickly.
Figure 19.02a
12.16A
 Lobster
clip
 http://www.youtube.com/watch?v=h6nhOC
hpMck
Crustaceans
 Crustaceans,
being aquatic, breathe using
gills.
 In
most cases the gills are attached to
appendages and movement of the
appendages aerates them.
Crustaceans
 Most
crustaceans are predatory, although
there are also many suspension feeders
such as barnacles.
 The
suspension feeders use their legs
which have a thick coating of bristles to
sweep food particles (such as plankton
and bacteria) through the setae.
Feeding barnacle
Crustacean reproduction
 Most
crustaceans have separate sexes,
although in some groups males are scarce
and parthenogenesis occurs.
 Most
crustaceans brood their eggs and the
offspring may be miniature versions of the
adults or may pass through several larval
stages.
Subphylum Crustacea
 Subphylum



Crustacea
Class Branchiopoda: fairy shrimp, brine
shrimp, water fleas, (e.g. Daphnia),
Class Maxillopoda: copepods, barnacles.
Class Malacostraca: Isopoda (pill bugs),
Amphipoda (beach fleas), Euphausiacea
(krill), Decapoda (lobsters, crayfish, crabs,
shrimps)
Subphylum Crustacea: Class
Branchiopoda
 The
Branchiopoda (Gk: “gill foot”) include
a number of fairly primitive organisms
including fairy shrimp and water fleas
(such as Daphnia).
 The
legs are the principal respiratory
organ and as a result are flattened and
leaflike.
Figure 19.15
12.22
Subphylum Crustacea: Class
Branchiopoda
 Most
branchipods also use their legs for
suspension feeding.
 The
most diverse group of the
branchiopods is the Cladocera, which is a
major component of the zooplankton fauna
in freshwater.
Cladocera
 Close
up of a cladoceran feeding
 http://www.youtube.com/watch?v=1KIVW8
cZQHU
Subphylum Crustacea: Class
Maxillopoda

The maxillopoda includes several groups of
crustaceans that were once considered classes
themselves, but recently been grouped together
based on their numbers of segments and a
uniquely structured eye.

Three important subclasses are the Copepoda
(small, diverse planktonic), Branchiura (fish
parasites) and the Cirripedia (barnacles).
Copepoda
 Subclass
Copepoda (Gk “oar foot”) are a
very diverse group of small (usually only a
few mm long), elongate and tapered
crustaceans.
 They
are a very important component of
aquatic food webs and often are the
commonest primary herbivore in aquatic
communities.
Figure 19.16c
12.24
Branchiura
 The
Branchiura (Gk: “gill tail”) are a group
of approximately 130 species of
dorsoventrally flattened ectoparasites
(usually of fish) often referred to as fish
lice.
 The body is very flat and oval and almost
entirely covered by the carapace.
Argulus: a fish louse
Branchiura

Mouthparts and antennae have been modified
into a proboscis with hooks and spines with
which the parasite grips its host.

Branchiurans are fast moving and often detach
and leave a host before reattaching to another
later.

Once they grab a host they quickly move to a
position behind the gill cover where they are less
likely to be knocked or swept off as the fish
moves.
Branchiura
 While
attached branchiurans feed on
mucus and skin cells or suck blood.
 They
can cause devastating losses to
commercial aquaculture facilities where
fish are confined at high densities
Cirripedia
 The
Cirripedia (L: “curl of hair” and “feet”)
are the barnacles.
 Sessile
and filter feeding as adults they
are covered with a shell of calacreous
plates secreted by the carapace.
 Cirri
are extended between plates to filter
feed.
Figure 19.19a
12.26A
Barnacle reproduction
 Barnacles
are monoecious, but usually
cross fertilize.
 Barnacles
are cemented in place so
mating is challenging. As a result,
barnacles have evolved what is
proportionally the longest penis in the
animal kingdom.
Dissected out barnacle penis
Barnacles feeding and mating
 http://www.youtube.com/watch?v=v1SW-
pl2gYs
Barnacle reproduction

Banacles brood their eggs until they develop into larvae,
which are then released into the water to find
somewhere to settle.

The initial barnacle larva is a nauplius, which transforms
into a non-feeding form called a cyprius.

The cyprius has food reserves for about two weeks. It
must find a place to attach permanently before it runs out
of food. If it locates a suitable spot, it glues itself to it
and transforms within 12 hours into an adult.
Nauplius larva of barnacle
Cyprius larva of barnacle
Female barnacle brooding eggs
Subphylum Crustacea: Class
Malacostraca

The Malacostraca (Gk: “soft” and “shell”) is the
largest and most diverse group of crustaceans.

Usually they have 8 thoracic and 6 abdominal
segments, each of which has a pair of
appendages.

They include the isopods (sow bugs and pill
bugs), Euphausiacea (krill) and decapods
(crabs, crayfish and lobsters).
Isopods
 Isopods
include the familiar pill bugs,
which live in damp places, but there are
many aquatic forms and some are
parasites of crustaceans and of fish.
Figure 19.21a
Pill bugs (Armadillidium vulgare)
Figure 19.22
Isopod fish parasite
(Anilocra)
Tongue-eating louse
 One
specialized isopod fish parasite
isCymothoa exigua, or the tongue-eating
louse.
 This
parasite enters through the gills,
destroys the tongue by feeding on its
blood supply so it atrophies and replaces it
becoming the fish’s new tongue.
http://dailyorganism.blogspot.com/2011/06/
tongue-eating-louse.html
Tongue eating louse
 http://www.youtube.com/watch?NR=1&fea
ture=fvwp&v=XtwaNBsSbHQ
Euphausiacea
 The
euaphausids include only about 90
species, are only about 3-6cm long, but
are very important components of the
oceanic plankton.
 Vast
swarms of them are fed on by fish
and whales.
Euphausiacea
 The
total biomass of the Antarctic krill is
estimated at over 500,000,000 tonnes and
of that more than half is eaten annually by
whales, penguins seals, squid, fish and
other predators.
 Krill
thus plays a central role in ocean food
webs feeding largely on phytoplankton and
converting their energy into biomass.
Northern krill
http://en.wikipedia.org/wiki/File:Meganyctip
hanes_norvegica2.jpg
Euphausids
 Euphausids
are found world wide in the
world’s oceans and live between 2 and 6
years depending on the species.
 The biomass losses through predation are
made up through growth and reproduction.
 Krill undergo extensive vertical migrations
in the water column descending during the
day to try to avoid predators and
ascending at night to feed.
Euphausids
 Because
Antarctic waters are areas where
great upwellings of nutrients occur these
oceans produce enormous quantities of
phytoplankton in the summer and this
phytoplankton is fed on by krill.
 The
krill thus convert the phytoplankton
into biomass larger animals can eat.
Whale feeding
 Krill
occur in vast, dense swarms that may
include 10,000-60,000 individuals per
square meter.
 These
massive swarms are what make
krill a profitable food source for whales to
feed on and explains why whales migrate
thousands of miles to feed in these waters.
Krill and whales
 http://www.youtube.com/watch?v=1_BqC9
IIuKU
Whale bubble netting clip
 http://www.youtube.com/watch?v=iREMH
Ez5PdU
Decapoda
 The
Decapods (Gk: “10 legs”) have 5 pairs
of walking legs the first of which usually
are modified into pincers (also called
chelae).
 The
group includes the lobsters, shrimp,
crabs and crayfish. Crabs differ from the
others in being much broader across the
carapace and having a shorter abdomen.
Decapoda
 There
are about 15,000 species of which
about half are crabs and about 3,000
species of shrimp.
 Commercially
a very important group and
extensively fished for and farmed.
 Most
decapods are scavengers and often
predatory.
Decapoda
 Decapods
primarily depend on their thick
exoskeleton and pincers for protection, but
hermit crabs occupy abandoned mollusc
shells and at least two species of crabs
use sea anemones as weapons which
they carry with them and thrust at anything
that threatens them.
Figure 19.26
12.31
Subphylum Hexapoda

Subphylum Hexapoda (six legs). Members of
the Hexapoda have three tagmata (head, thorax
and abdomen) and three pairs of walking legs.
There are two classes.


Class Insecta: beetles, flies, wasps, ants,
grasshoppers, bugs, caddisflies, fleas, butterflies and
moths, lice, cockroaches, dragonflies, etc.
Class Entognatha: collembolans, springtails and
snowfleas.
Subphylum Hexapoda
 Insecta
can be distinguished from
Entognatha by the fact that insects have
the bases of their mouthparts visible
outside the head capsule, whereas the
Entognatha do not.
Class Entognatha

The Entognatha includes three classes the members of
all of which are small (<10mm), inconspicuous
organisms.

The most obvious are the members of the order
Collembola the springtails and snowfleas.

They are very common in soil and sometimes swarm on
ponds or snowbanks. They are called springtails for the
springing organ they possess, which folds underneath
the abdomen and can launch them high into the air if
threatened.
An aggregation of springtails
Springtail
Subphylum Hexapoda: Class
Insecta
 The
insects are spectacularly successful,
there being more species of insects than
the total number of species in all the other
classes of animals combined.
 There
are about one million named
species of insect with probably millions
more as yet undescribed.
Class Insecta

Insects occupy virtually all terrestrial and
freshwater habitats, marine environments being
the only one where they are scarce.

They are a highly adaptable group that can
withstand severe conditions and have evolved a
suite of adaptations to minimize water loss
including a waxy cuticle, the ability to close their
spiracles, and the ability to extract almost all
water from food and fecal material.
Class Insecta
 Insects
have three pairs of legs and
usually two pairs of wings on the thorax.
 Head
has a pair of large compound eyes,
each eye being made up of up to 30,000
ommatidia, which are individual tube-like
structures. Insect eyes are especially
good at detecting motion and have a very
wide field of view.
Figure 20.22
12.20
Class Insecta
 The
head also has a pair of antennae and
complex, multipart mouthparts.
 The
mouthparts equip different species of
insect to feed on a wide variety of foods
from nectar, to blood, to other insects, to
plants.
Figure 20.19
12.44
Class Insecta: flight
 Insects
possess wings that were evolved
independently (not surprisingly) of the
birds and bats.
 The
wings are outgrowths of the cuticle of
the thorax. In most insects there are two
pairs, but in flies only one. The second
pair in flies has been modified into halteres
(balancing organs)
Figure 20.04a
Class Insecta: flight

Flight offers numerous advantages to insects
enhancing the ability to search for food, mates
and habitat, escape from predators, and
migrate.

It also is expensive in terms of the musculature
required to fly and in some species (e.g.
crickets) different flying and non-flying morphs
occur depending on whether flying is
ecologically beneficial or not.
Class Insecta: flight
 Wings
differ in size and shape from the
long narrow wings of dragonflies to the
broader shorter wings of many butterflies
and moths.
 Wing
beat rate varies greatly from a low of
about 4 per second for butterflies to 100/s
for bees to 1,000/s for some midges.
Class Insecta: flight
 The
fastest flying insects can reach about
30 miles per hour (horseflies and sphinx
moths) with dragonflies reaching about
25mph.
 The
kings of long distance migration are
the monarch butterflies which travel
hundreds of miles on migration at a speed
of about 6mph.
Class Insecta:
Gas Exchange

Gas exchange in insects is achieved by a series of tubes
called tracheae. These tubes open to the outside via
spiracles that can be opened to allow air in and closed to
reduce water loss.

The tracheae branch into a very fine network of fluidfilled tracheoles so that no cell is located far from a
tracheole.

In aquatic insects tracheal gills have evolved which are
extensions of the body wall penetrated by many
tracheoles.
Figure 20.20a
Figure 20.20b
Class Insecta:
Metamorphosis
 Insects
go through a series of
developmental stages before adulthood.
 Most
insects (88%) go through complete
metamorphosis: egg, larva, pupa, adult. In
complete metamorphosis individuals of the
same species at different stages of the life
cycle do not compete with each other.
Class Insecta


The larval stage is the primary feeding stage
where growth occurs. Indeed in some insects
the adults are non-feeding and often short-lived
e.g. mayflies, some butterflies.
The pupal stage is a non-feeding stage in which
the larva transforms into an adult. Often this
stage is an overwintering stage.
 The adult stage is the reproductive stage in
which eggs are laid and the cycle repeats.
Figure 20.24
12.46
Class Insecta
 Insects
such as grasshoppers, mayflies,
lice, and bugs do not undergo complete
metamorphosis but instead undergo
incomplete metamorphosis.
 In
incomplete metamorphosis the young
are called juveniles (or nymphs) and look
like the adult but smaller, gradually
increasing in size via a series of molts.
Class Insecta: important orders
Coleoptera: beetles; Forewings modified into
hardened covers or elytra. Biting, chewing
mouthparts.
waynesword.palomar.edu
Hymenoptera: ants, bees, wasps; narrow-waisted,
includes a wide variety of social species.
Lepidoptera: butterflies and moths; membranous wings
covered in fine scales. Mouthparts are a sucking tubes
that curls up when not in use.
en.wikipedia.org
Diptera: true flies; single pair of wings and a pair of
modified wings (halteres) which act as gyroscopes.
en.wikipedia.org
Hemiptera: true bugs; Piercing sucking
mouthparts.
www.oocities.org
www.earthlife.net
Orthoptera: grasshoppers, locusts, mantids;
chewing mouthparts.
en.wikipedia.org
Siphonaptera: fleas; Wingless with laterally
compressed bodies. Specialized for blood
sucking.
hardinmd.lib.uiowa.edu
Trichoptera: caddisflies; small softbodied. As larvae
inhabit cases they construct of sand, gravel and plants
material in streams.
Isoptera: termites; highly social wood eating insects.
www.evrimteorisi.info
Social behavior
 In
many groups of insects there is a
considerable degree of social behavior.
 This
ranges from temporary associations
that are quite uncoordinated such as
groups of hibernating or roosting carpenter
bees to true societies of the Hymenoptera
(bees and ants) and termites (Isoptera)
Evolution of Eusociality

In the complex eusocial (truly social) societies of
Hymenoptera and Isoptera communities are
permanent and all stages of the life cycle occur
within the nest.

There is division of labor and highly coordinated
behavior.

Many individuals do not reproduce. Instead they
act as helpers at their parents’ nests for their
entire life. This is an extreme type of altruism.
Evolution of Eusociality in insects
 Eusociality
describes social systems with
three characteristics:



Overlap in generations between parents and
offspring.
Cooperative brood care.
Specialist castes of non-reproductive
individuals.
Honey Bee nests
 Honey
bees have a very complex social
system that lasts potentially indefinitely as
the group survives from season to season.
 Up
to 70,000 bees may occupy a hive and
there are 3 castes: a single reproductive
queen, a few hundred males (drones),
and many thousands of female workers
who are non breeders.
Honey Bee nests
 The
workers tend to the hive’s young,
gather nectar and pollen and make honey,
and guard the hive.
 What
caste individuals belong to is
determined by fertilization (males develop
from unfertilized eggs) and what the
developing larva is fed.
Honey Bee nests

Larvae that will become queens are fed royal
jelly, which is secreted by the salivary glands of
nurse workers.

Workers only produce royal jelly when the level
of “queen substance” in the hive declines
(because the queen has died or is too old).

Queen substance is a pheromone produced by
the queen that suppresses sexual maturation of
workers.
Honey bee foraging
 Honeybees
are remarkable for their ability
to collaborate in their search for food.
 An
individual who has found food dances
to convey information about the food
source’s location to other foragers.
Karl von Frisch
pioneered the
work on dancing
bees.
Honey bee foraging
A
honey bee that has found food dances
to indicate the location of the food to other
foragers.
 If
the food is close (<50m) the bee
performs a round dance. This tells the
other bees that food is near the hive.
Round dance
Round dance
Honey bee foraging
 If
food is further away bee performs a
“waggle” dance.
 Bee
performs dance on a path that is
roughly figure 8 shaped.
 Bee
travels in straight line while waggling
her body. Then turns left or right to circle
back to the beginning.
If bee outside hive, direction of
waggle dance points directly at
source of food.
Honey bee foraging

Inside in the hive it is dark and the bee performs
the dance on a vertical surface.

Vertical indicates the direction of the sun and the
direction of the dance relative to the vertical
indicates the angle of the food relative to the
sun.

The length of the waggle portion indicates the
approximate distance to the food. The fewer
circuits the bee performs in a period of time the
further away the food is located.
Vertical
orientation in hive
Waggle dance.
Waggle dance
 http://www.youtube.com/watch?v=aUCoLe
I5Qxg
Ant sociality

The ants who are close relatives of the bees (both are
members of the Hymenoptera) also have highly
organized colonies.

As in bees a queen is responsible for egg laying and the
workers are females. There may be several different
castes of worker females: soldiers specialized for
defense; and different sized workers specialized for food
gathering and tending the young.

Males are produced only for reproduction and die after
mating.
Ant sociality
 Ants
have evolved many remarkable
behaviors including:

Slave making: some species raid the nests of
other species of ants and steal their larvae,
which grow up to become the workers in their
new nest. Specialist slave makers produce
no workers of their own.
Ant sociality
 As


well as:
Farming: Numerous species of ants farm
various different species of fungus gathering
leaves to turn into compost and destroying
pests that attack the fungus.
Herding: ants protect “herds” of aphids from
parasitoids and predators and eat the
honeydew (partially digested plant juices) that
the aphids secrete.
Termite colonies
 Termites
belong to a different order of
insects than bees and ants (the Isoptera)
and their colonies have a similar but not
identical organization.
 As
in the Hymenoptera there are both
sterile and fertile individuals in a termite
colony.
Termite colonies
 Nonreproductive
females become either
workers or soldiers (which have large
heads and mandibles with which they
protect the colony).
 Termites
specialize in eating wood and
depend on bacteria to digest it as they do
not produce enzymes capable of digesting
cellulose.
Haplodiploidy and eusocial
Hymenoptera
 One
idea advanced to explain eusociality
is the unusual genetic system
(haplodiploidy) of the Hymenoptera (ants,
wasps, bees, etc.).
 Males
are haploid and females diploid
because males develop from unfertilized
eggs and females from fertilized eggs.
Haplodiploidy and eusocial
Hymenoptera
 Daughters
receive all of their fathers
genes and half of their mothers genes.
Thus, daughters share ¾ of their genes.
 This
suggests females would be better off
if they favored the production of
reproductive sisters rather than their own
offspring.
Haplodiploidy and eusocial
Hymenoptera
 Queens
are equally related to all offspring
and so should prefer a 1:1 ratio of sons to
daughters among reproductives.
 Females
workers however should prefer a
1:3 ratio of brothers to sisters among
reproductives.
Haplodiploidy and eusocial
Hymenoptera
 It
has been shown in wood ants that
queens produce equal numbers of male
and female eggs, but the hatching ratio is
heavily female biased. Workers
apparently selectively destroy male eggs.
Haplodiploidy and eusocial
Hymenoptera
 Haplodiploidy
appears to influence worker
behavior, but consensus among scientists
today is that it does not explain the
evolution of eusocial behavior in
Hymenoptera.
 There
are several reasons why.
Haplodiploidy and eusociality
 First,
haplodiploid explanation assumes all
workers have the same father. However,
honeybee queens mate with more than 17
males on average.
 As
a result relatedness between worker
honeybees often below 1/3.
Haplodiploidy and eusociality
 Second,
in many species, more than one
female founds a nest. In this case workers
may be completely unrelated.
Haplodiploidy and eusociality
 Third,
many eusocial species are not
haploid (e.g. termites) and many
haplodiploid species are not eusocial.
Haplodiploidy and eusociality
 Phylogenetic
analysis of Hymenoptera by
Hunt (1999) emphasizes that eusociality is
relatively rare even though haplodiploidy
occurs in all groups.
 Eusociality
occurs in only a few families
which are scattered around the tree, which
suggests eusociality has evolved
independently multiple times.
Haplodiploidy and eusociality
 Hunt
also points out that eusociality has
only evolved in groups that build complex
nests, and care for young for a long time.
 Association
between nest building, long
term care and eusociality suggests main
driving force for eusociality is ecological
not genetic.
Haplodiploidy and eusociality
 Nest
building and need to supply offspring
with a steady stream of food make it
impossible or very difficult for a female to
breed alone.
 Also,
if predation rates are high, solitary
breeding individuals may not live long
enough to raise their young.
Insects and humans: benefits
 Insects
and humans obviously interact in
many ways and insects are both harmful
and beneficial.
 Benefits
include the fact that insects
produce a number of commercially
valuable products including honey and silk
and historically were used to make certain
dyes.
Insects and humans:benefits

Another very important role insects play is in the
pollination of food crops. Today in the U.S.,
however, the spread of bee mites, which wipe
out hives of honey bees, currently threatens this.

Historically the introduction of European honey
bees greatly reduced the numbers of native
pollinating insects, such as bumblebees, and
these species now are too scarce to make up
the pollination deficit.
Insects and humans: costs

There are a huge number of insects that
consume crops, trees and ornamental plants
and we fight an ongoing battle with these pests.

The success of some of these pests is because
they were introduced here and escaped their
native predators and parasites (e.g. Japanese
beetles, gypsy moths, various bark beetles,
scale insects) or simply because they thrive in
monocultures of crops.
Insects and humans: costs

The costs both economic and ecological of
pesticide based control of insect pests are
enormous.

Attempts to reduce dependence on pesticides
have led to increased use of biological control
agents and the use of integrated pest
management approaches in which strategies
such as rotating crops, planting multiple different
crops, planting pest resistant varieties, and
employing biological controls are used together
to limit pesticide use.
Insects and humans: costs

Insects also are major vectors of disease and
transmit many serious disease agents.
 Vectors include:






Mosquitoes: malaria, yellow fever, filariasis, West Nile
virus.
Blackflies: river blindness
Fleas: bubonic plague
Tsetse flies: sleeping sickness
Rhodnius bugs: Chaga’s disease
Lice: typhus