Aphid Population
Soldier Types and their
Association with Non-Soldiers
Christina Sartorio
Zachary Brady
Fossil History


Aphids are related to
Adelgids and Phylloxerids
who evolved about 280
million years ago
The oldest known fossil is
Triassoaphis cubitus from
the Triassic about 220
million years ago
Species of Aphids
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There are about 4000 species
of aphids in the world of which
about 250 are serious pests.
Scientists believe that the
number of species remained
relatively small until the
angiosperms (flowering plants)
became more common, then as
the aphids adapted to these
new and rapidly varying plants
their species numbers also
increased.
Aphid Range and Appearance


Twenty-five percent of all plant
species are infested with
aphids, and though it is believed
the species of aphids has
followed that of plants, not all
groups of plants are equally
infected with these parasites.
Aphids are part of the
Superfamily Aphidoidae and are
described as small (1-10 mm)
soft bodied insects with, or more
commonly without, wings.
Species Variation

The Compositae, the 3rd most
common plant family, supports
the most aphid species (605
species), but the Orchidacea,
the 2nd most common plant
family, only supports 9 species
of aphids while the Rosaceae
which is only the 22nd most
common plant family supports
the 3rd highest number of
aphid species (293 species).
Aphid Anatomy

Aphids possess a proboscis
which originates between and
behind the forelegs, their
antennae has two thick basal
segments and a flagellum
composed of up to 4
segments, the last of which is
divided into a proximal part
and a thinner distal part
Feeding Habits

Aphids feed from the phloem of
plants which they tap into with
the stylets of their proboscis.
They gain access to the
phloem vessels from 3 main
parts of the plant, stems,
leaves, and roots. Their stylets,
which are contained within the
proboscis when the aphid is
not feeding, are very thin and
could suffer damage while
being pushed into the plant or
bend in an unwanted direction.
Movement
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
Most aphids do not have
wings, and in general they
move very little, and their lives
consist of feeding and giving
birth.
Aphids are weak fliers and in
still air they move at about 1.6
to 3.2 km per hour. Their
migrations can be extensive
and they often take advantage
of favorable winds to enhance
their flight efficiency.
Protection
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An aphid will kick out at an
attacker and attempt to drive it
off, if this does not work it will
pull up its stylets and proboscis
and walk away.
Some species can also exude a
special waxy solution from their
siphunculi over an attacker,
while doing this it generally
releases an alarm pheromone
alerting nearby aphids that
danger is close at hand.
Predators
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Aphids are relatively common
and in the right circumstances
they occur in large numbers, for
this reason there are quite a
number of animals which use
aphids as a food source.
Some include the Chinese
praying mantis and the ladybug.
Behavioral Classes
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Some species have “soldier”
aphids and others only have
“non-soldier” aphids.
Soldiers are not as common as
non-soldiers, but are more apt
to fending off predators and
various dangers than nonsoldiers.
The Project
Purpose:
To determine whether or not there exists a significant
genetic difference between soldier and non-soldier
aphids.
Hypothesis:
If genetic data from non-soldier and soldier aphids are
compared, then a significant difference between the two
will be apparent.
Procedure
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Using the Student Interface to
the Biology Workbench, we
searched the databases for
aphid genes.

We found a common gene
named cytochrome oxidase
subunit I. This gene is the last
carrier in the electron transport
system of cellular respiration.
Soldiers
Searching for the
cytochrome oxidase
subunit I gene, we found
8 soldier aphid species:
-Pseudoregma koshunesis
-Pseudoregma alexanderi
-Ceratovacuna nekoashi
-Ceratoglyphina styracicola
-Nipponaphis distyliicola
-Tuberaphis taiwana
-Tuberaphis styraci
-Pseudoregma bambucicola
Non-soldiers
We also found 14 non-soldier
species:
-Chaitophorus tremulae
-Chaitophorus leucomelas
-Chaitophorus populialbae
-Sitobion avenae
-Acryrthosiphon pisum
-Acryrthosiphon kondoi
-Macrosiphum creeli
-Fibriaphis fimbriata
-Euschizaphis sp.
-Diuraphis noxia
-Schizaphis graminum
-Paradoxaphis plagianthi
-Paradoxaphis aristoteliae
-Paradoxaphis plagianthi
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Using these genes, we created ten groupings, each
containing genes from six aphid species. There were
three soldier species and three non-soldier species in
each group.
After feeding these groups into the program, we used
the “Clustalw” program to align the genetic sequences.
Then, to make the data easier to analyze, we used the
“DrawTree” program to make the sequences into trees.
The next 10 slides show the resulting trees.
Tree 1
Tree 2
Tree 3
Tree 4
Tree 5
Tree 6
Tree 7
Tree 8
Tree 9
Tree 10
Observations and Results
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The results were varied. Some of the trees
clearly demonstrated the hypothesis, such as
numbers 2 and 9.
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However, the vast majority of the trees were less clear.
In many of these, one or more of the non-soldier aphids
were genetically closer to the soldier aphids than their
fellow non-soldiers.
This occurred in trees numbered 1, 3, 4, 5, 6, 7, 8, and
10.
Conclusion

Our hypothesis, a
significant difference
between non-soldier and
soldier species will be
apparent, was not
supported by our
research.
Further Research


A possible explanation for
our results is that the
aphid population first split
genetically according to
plant species or
geographic area. Further
research is needed to
examine this possibility.
Also, further research can
be done using a larger
sample size of aphid
species.