PREFACE
In recent years
the study of agricultural science has undergone many changes, most of
which have resulted in greater
emphasis on practical
materials and specific presentation
of facts to encourage enquiry into the production of plants and animals.
In order to fully understand some of the important areas,
the Prof .E. Oti believe that it is essential for all students who study agricultural
science as a course in higher
institution to have a thorough grounding in the basic areas of agriculture
Further
more, he believes that a study of
agricultural science can be made more
meaningful by the use of a well annotated diagram, especially where these illustrates the stages in the
development of physical
features and in the presentation of agricultural ideas and concept.
TABLE OF CONTENT
Dedication…………………………………….……………..…………..i
Acknowledgement ……………………………………..…………..…ii
Preface ……………………………………………………………….….iii
Table of content ……………………………………….……………….iv
CHAPTER ONE
Introduction ……………………………………………………………..1
CHAPTER TWO
Etymology ……………………………………………….……………….5
CHAPTER THREE
Taxonomy and evolution ……………………….…………………..6
CHAPTER FOUR
Distribution and diversity ……………………………………….…..8
CHAPTER FIVE
Morphology……………………………………………………………..10
References
CHAPTER ONE
INTRODUCTION
Ants are social insects of the
family formicidae and also with the
related wasps and bees, belong to the order Hymenoptera. Ants evolved from
wasp – like ancestors in the mid- cretaceous period between 110 and 130 million
years ago and diversified after the rise
of flowering plants. More than 12,500
out of an estimated total of 22, 000
species have been classified. They are easily identified by their elbowed
antennae and a distinctive node-like structure that forms a slender waist.
Ants form
colonies that ranges in size from a few
dozen predatory individuals living in
small natural cavities to highly organized colonies that may occupy large
territories and consist of millions of individuals. Larger colonies consist
mostly of sterile wingless females forming castes of “workers” “soldiers”,
or other specialized groups.
Newly all ant colonies also have some fertile males called “drones: and one or more fertile females called “queens”. The colonies sometimes are
described as superorganisms because the ants appear to operate as a unified
entity, collectively working together or support the
colony.
Ants have
colonized almost every landmass on
earth. The only places lacking indigenous ants are Antarctica and a few remote
or inhospitable islands. Ants thrive in most
ecosystems and may form 15-25% of the terrestrial animal biomass. Their success in so many environments has been attributed to their social prganisation and their ability to
modify habitats, tap resources, and defend themselves. Their long
co-evolution with other species has led
to mimetic, commensal, parasitic, and mutualistic relationships.
Ant societies
have division of labour, communication
between individuals, and an ability to
solve complex problems. These parallels
with human societies having long been an medication, and rituals. Some species are
valued in their role as biological pest control agents. Their ability to exploit resources may bring ants
into conflict with humans, however, as they can damage crops and invade
buildings. Some species, such as the red
imported fire ant, are regarded as invasive species, establishing
themselves in areas where they have been introduced accidentally.
Scientific classification
Kingdom: Animalia
Phylum: arthropoda
Class: insecta
Order: hymenoptera
Suborder: apocrita
Superfamily: bespoidea
Formicidae
Family
-
aenictogitoninae
-
agroecomyrmecinae
-
amblyoponinae(Incl. ‘Apomyrminae”)
-
aneuretinae
-
cerapachyinae
-
dolichoderinae
-
ecitoninae (incl. Dorylinae” and Aenictinae”)
-
ectatomminae
-
formicinae
-
heteroponerinae
-
leptanillinae
-
leptanilloidinae
-
martialinae
-
myrmeciinae (incl. “nothomyremeciinae”)
-
myrmicinae
-
paraponerinae
-
ponerinae
-
proceratiina
-
pseudomyrmecinae
CHAPTER TWO
ETYMOLOGY
The word ant is
derived from ante of middle English
which is derived from amette
of old English and is related to the old high German ameiza, hence the modern
German ameise. All of these words come
from west Germanic “amaitho, and the original meaning of the word was “the
biter” the family name formicidae is derived from the latin formica (ant) from
which the words in other romance languages such as the Portuguese formiga, Italian Formica, Spanish hormiga, Romanian furnica and French fourmi
are derived. It has been hypothesized that a proto-indo- European word morwi
was used, Sanskrit vemrah, Latin formic,
Greek myrmex, old church Slavonic maraviji, old irish moirb, old Norse maurr.
CHAPTER THREE
TAXONOMY AND
EVOLUTION
The family
formicidae belongs to the order Hymenoptera, which also includes sawflies,
bees, and wasps. Ants evolved from a lineage within the vespoid wasps. Fossil
evidence indicates that were present in the Late Jurassic, 150. 16
after the rise of flowering plants about 100 million years ago they diversified
and assumed ecological dominance around 60 million years ago. (17)(18)(19) in
1966, E.O.Wilson and his collegeagues identified the fossil remains of an ant
(sphecomyrma freyi) that lived in the cretaceous period. The specimen, trapped
in amber dating back to more than 80 million years ago, has features of both
ants and wasps. sphecomyrma probably was a ground forager, but some suggest on
the basis of groups such as the Leptanillinae and Martialiae, that primitive
ant were likely to have been predators underneath the surface of the soul.
During the
cretaceous period, a few species of primitive ants ranged widely on the
laurasian super-continent (the northern hemisphere). They were scarce in
comparison to the populations of other insects, representing only approximately
1% of the entire insect population. Ants became dominant after adaptive
radiation at the beginning of the all insets found in major fossil deposits. Of the species that lived in the Eocene
epoch, approximately one in ten genera survive to the present. Genera surviving
today comprise 56% of the genera in Baltic amber fossils (early Oligocene), and
92% of the genera in Dominican amber fossils (apparently early Miocene).
Termites,
although sometimes called white ants, are not ants. They belong to the order
isopter. Termites are more closely related to cockroaches and mantids. Termites
are eusocial, but differ greatly in the genetics of reproduction. That their
social structures is similar to that of ants, is attributed to convergent
evolution. velvet ants look like large ants, but are wingless female wasps.
CHAPTER FOUR
DISTRIBUTION
AND DIVERSITY
NUMBER OF REGION SPECIES
Neotropics |
2162
|
|
Narcotic
|
580
|
|
Europe
|
180
|
|
Africa
|
2500
|
|
Asia
|
2080
|
|
Melanesia
|
275
|
|
Australia
|
985
|
|
Polynesia
|
42
|
Ants are found
on all continents except antrctic, and only a few large islands such as gree
land, Iceland, parts of Polynesia and the Hawaiian islands lack native ant
species. Ants occupy a wide range of ecological niches, and are able to exploit
a wide range of food resources either as direct or indirect herbivores,
predators, and scavengers. Most species are omnivorous generalists, but a few
are specialist feeders.
Their ecological dominance may be
measured by their biomass and estimates in different environments suggest that
they contribute 15-20% (on average and nearly 25% in the tropics) of the total
terrestrial animal biomass, which exceeds that of the vertebrates.
Ants range in
size from 0.75 to 52 millimetres (0.03-2.0in), (28)(29) the large species being
the fossil Titanomyrma giganteum, the queen of which was 6 centimetres (2.4 in)
long with a wingspan of 15 centimetres (5.9 in). (30) ants vary in colour; most
ants are red or black, but a few species are green and some tropical species
have a metallic luster.
More
than 12,000 species are currently known (with upper estimates of the potential
existence of about 22,000) (see the article list of ant genera), with the greatest
diversity in the tropics. Taxonomic studies continue to resolve the
classification and systematic of ants. Online databases of ant species,
including ant base and the hymenoptera Name server, help to keep track of the
known and newly described species. (31) The relative ease with which ants may
be sampled and sampled and studied in ecosystems has made them useful as
indicator species in biodiversity studies.
CHAPTER FIVE
MORPHOLOGY
Ants
are distinct in their morphology from other insects in having elbowed antennae,
metapleural glands, and a strong constriction of their second abdominal segment
into a node-like petiole. The head, mesosoma, and metasoma are the three
distinct body segments. The petiole forms a narrow waist between their mesosoma
(thorax plus the first abdominal segments, which is fused to it) and gaster
(abdomen less the abdominal alone, or the second and third abdominal segment).
Bull ant showing
the powerful mandibles and the relatively large compound eyes that provide
excellent vision.
Like
other insects, ants have an exoskeleton, an external covering that provides a
protective casing around the body a point of attachment for muscles, in
contrast to the internal skeletons of humans and other vertebrates. Insects do
bot have lungs; oxygen and other gases such as carbon dioxide pass through
their exoskeleton via valves called spiracles. Insects also lack closed blood
vessels; instead, they have a long, thin, perforated tube along the top of the
body (called the “dorsal aorta”) that functions like a heart, and pumps
haemolymph toward the head, thus driving the circulation of the internal
fluids. The nervous system consist of a vental nerve cord that runs the length
of the body, with several ganglia and branches along the way reaching into extremities
of the appendages.
5.1
Head
An ants head contains many sensory organs. Like most insects, ants have
compound eyes made from numerous tiny attached together. Ant eyes are good for
acute movement detection, but do not offer a high resolution image. They also
have three small compared to vertebrates, most ants have poor-to-mediocre
eyesight and a few subterranean species are completely blind. Some ants such as
Australia’s bulldog ant, however, have exceptional vision.
Two antennae (“feelers”) are attached to the head; these organs detect
chemicals, air currents, and vibrations; they also are used to transmit and
receive signals through touch. The head has two strong jaws, the mandibles, use
to carry food, manipulate objects, construct nests and for defence. (25) in
some species a small pocket (infrabuccal chamber) inside the mouth stores food,
so it may be passed to other ants or their larvae. (37).
5.2
Legs
All six legs are attached to the mesosoma (“thorax”). A hooked claw at
the end of each leg helps ants to climb and to hang onto surfaces.
5.3
Wings
Most queens and the small number of drone in a colony (the male ants),
have wings queens shed the wings after the nuptial flight, leaving visible
stubs, a distinguishing feature of queens. Wingles queens (ergatoids) and males
occur in a few species, however. (35)
5.4
Metasoma
The metasoma (the “abdomen”) of the ant houses important internal
organs, including those of the reproductive, respiratory (tracheae), and
excretory systems. Workers of many species have their egg-laying structures
modified into sting that are used for subduing prey and defending their nests,
(35)
5.5
Polymorphism
Seven
leafcutter ant workers of various castes (left) and two Queens (right) in the
colonies of a few ant species, there are physical casts-workers in distinct
size classes, called minor, median, and major worker. Often the larger ants
have disproportionately larger heads, and correspondingly stronger mandibles.
Such individuals sometimes are called “soldier” ants because their stronger mandible
make them more effective in fighting, although they still are workers and their
”duties” typically do not vary greatly from the minor or median workers. In a few species the median workers are absent, creating a sharp divine between the minors and majors. (38) weaver ants, for example, have a distinct bimodal size distribution. (39)(40) some other species show continuous variation in the size of workers. The smallest and largest workers in pheidologeton diversues show nearly a 500-fold difference in their dry weights. (41) workers cannot mate; however, because of the haplodiploid sex-determination system in ants, workers of a number of species can lay unfertilized eggs that become fully fertile, haploid males. The role of workers may change with their age and in some species, such as honeypot ants, young workers are fed until their gasters are distended, and act as living food storage vessels. These food storage workers are called replete. (42) This polymorphism in morphology and behaviour of workers initially was thought to be determined by environmental factors such as nutrition and hormones that led to different developmental paths; however, genetifc differences between workers have noted in Acromyrmex sp. (43) these polymorphisms are caused by relatively small genetic changes; differences in a single gene of solenopsis invicta can decide whether the colony will have single or multiple queens. (44) The Australian jack jumper ant one chromosome as they are haploid), the lowest number known for any animal, making it and interesting subject for studies in the genetics and developmental biology of social insects. (45)(46)
”duties” typically do not vary greatly from the minor or median workers. In a few species the median workers are absent, creating a sharp divine between the minors and majors. (38) weaver ants, for example, have a distinct bimodal size distribution. (39)(40) some other species show continuous variation in the size of workers. The smallest and largest workers in pheidologeton diversues show nearly a 500-fold difference in their dry weights. (41) workers cannot mate; however, because of the haplodiploid sex-determination system in ants, workers of a number of species can lay unfertilized eggs that become fully fertile, haploid males. The role of workers may change with their age and in some species, such as honeypot ants, young workers are fed until their gasters are distended, and act as living food storage vessels. These food storage workers are called replete. (42) This polymorphism in morphology and behaviour of workers initially was thought to be determined by environmental factors such as nutrition and hormones that led to different developmental paths; however, genetifc differences between workers have noted in Acromyrmex sp. (43) these polymorphisms are caused by relatively small genetic changes; differences in a single gene of solenopsis invicta can decide whether the colony will have single or multiple queens. (44) The Australian jack jumper ant one chromosome as they are haploid), the lowest number known for any animal, making it and interesting subject for studies in the genetics and developmental biology of social insects. (45)(46)
REFERENCE
1.
Ward,
Philip s (2007) “Phylogeny,
Classification, and Species Level
Taxonomy of Ants (Hymenoptera:
Formicidae)” (PDF). Zootaxa
1668:549-563
2.
Reeling
C, Brown JM & Verhaagh M(2008) “ Newly discovered Sister Lineage Sheds Light on Early Ant
Evolution” PNAS 105(39): 14913-7 Bibcode 2008PNAS..10514913r.Doi:10.1073/pnas.
0806187105. PMC 2567467. PMID 18794530
3.
Hymenoptera
Name Server. Formicidae Species Count”
Ohio State University
4.
Oster
GF. Wilson Eo (1978) cast and ecology in the social insects Princeton
university press, Princeton. Pp.21 -22 ISBN 0-691 –02361-1
5.
Holldobler
and Wilson , p. 471
6.
Holldobler
and Wilson (1990) pp, 619-629
7.
Pest Notes: Ants
(publication 411)” University of California Agriculture and
Natural Resources 2007. achieved from
the original on 5 July 2008.
retrieved 5 June 2008
8.
Formic Etymonline, Com, Retrieved 2012 –01-30
9.
Brother
DJ (1999) “Phylogeny And Evolution of wasps, Ants and Bees (Hymenoptera, chrysisoidea, vespoisea, and
apoidea)” zoological scripta 28 233-249.
10.
Simpson
DP (1979) Cassells’ Latin Dictionary (5ed) London: Cassell Ltd. ISBN
0-30452257-0
11.
|
Two
Recent Fossil Discoveries show insects recycling traits” science Blog, University of Colorado at boulder . 1996 retrieved
May 18, 2012