1. Characteristics of Zoological Pests
of Crops & Crop Products CHAPTER : 3
 Systematic Position :-
 Phylum : Arthropoda
 Class : Hexapoda
 Sub-class : Insecta
 Super(Infra)-class : Apterygota/Pterygota
 Order : Lepidoptera/Hemiptera/Orthoptera/Diptera/Isoptera/Thysa-
-noptera/Coleoptera/Hymenoptera
 Characters :-
 Body fragmented into head , thorax(pro, meso & meta) & abdomen .
 Body enveloped with chitinous exoskeleton(cuticle) .
 Compound eyes or ocelli(ocellum) usually found , whatever those
may be inactive ; eg. Isopteran insects .
 Antennae(a pair of antenna) , jaws conspicuously present .
 3 pairs of leg(appendage) . Each thoracic part bears a pair of
appendage . Six leg segments viz. coxa, trochanter , femur , tibia ,
tarsus & pre-tarsus .
 Wing usually two pairs – variously modified , reduced or rarely
absent .
 Respiratory organ is trachea with spiracles . In a few certains ,
tracheal or blood gills .
 Excretory organ – Malpighian’s tubules exclusively .
 Metamorphosis – complete & incomplete , varying order to order as
well as wings development .

2. The greatest significance of insects lies on their being pests of crops and
animals and as carries of disease . A large number of insects cause injury to
economic plants by feeding on externally and chewing foliar parts or another
parts by sucking saps with help of piercing-sucking type of mouthparts and
reducing vitality of the plants by disseminating various phyto-maladies and by
living a sub-terranean life and infesting the rootmass . Recent estimates put
the total annual loss due to insect-pests to major agronomical crops & stored
foodgrains in India to the tune of Rs. 750/- billion .
Lepidoptera(lepidos = scale , pteron = wing) : All moths* & butterflies* .
Hemiptera(hemi = half) : Nephotettix sps.
Orthoptera(orthos = straight) : Poekilocerus pictus/Hieroglyphus sps.
Diptera(dis = two) : All flies except sawfly .
Isoptera(isos = equal/similar) : All termites cum white ants
Thysanoptera(thusanos = fringe) : Thrips sps.
Coleoptera(koleos = sheath) : All beetles
Hymenoptera(hymen = membrane) : All bees, wasps , etc.
 Systematic Position :-
 Phylum : Arthropoda
 Class : Arachnida
 Order : Acari
 Characters :-
 Body fragmented into cephalothorax & abdomen usually except
Acarina
 Body enveloped with numerous setae(seta)
 No compound eyes .

3.  Neither antennae nor jaws .
 Usually four pairs of thoracic appendages except eriophydae(2pairs)
– a pair of chelicerii(pincer) , a pair of pedipalpi(sucker) and four
pairs of legs .
 No wing .
 Respiratory organs – gill-books, lung-books .
 Excretory organs – Malpighian’s tubules & coxal glands .
 No metamorphosis usually . except Acarina
Tarsonemidae : Steneotarsonemus spinki , Polyphagotarsonemus , etc.
Tetranychidae : Petrobia latens , Tetranychus sps. Olygonychus , etc.
Tenuipalpidae : Brevipalpus phoenicis , etc.
Eryophydae : Aceria sps.
Mites have wide range of hosts and various habitats . They live in marine
& fresh water , in organic debris of all kinds , and on plants and animal . They
cause serious damage to agrl crops stored foodgrains and livestock .
phytophagous mites suck saps from lowerfoliar surface with help of piercing-
sucking type of mouthparts . Consequently, leaves wrinkled , turn downwards
with elongation of petiole and show blotches . Severe case may cause entire
defoliation of plants .
In case of Aceria guerrerhonis(Eryophydae) known as Perianth mite of
Coconut ; while nuts at button stage , symptom is found as yellowish-brown
spots at very beginning stage which later turn brown[formation of brown ,
longitudinal fibrous fissures starting from perianth(cap like structure holding
nuts with fruitstalk) covering nut surface] . In course of development ,
numerous cracks on adversely affected area . nut size become so poor &
quality drastically detoriated . Severe case may cause cent per cent nut fall .

4.  Systematic Position :-
 Phylum : Chordata
 Class : Mammalia
 Order : Rodentia
 Characters :-
 Body enveloped with hairy exo-skeletonous wrapper .
 Mammary glands present .
 Legs(limbs) – two pairs .
 Two pairs of cardiac chambers & pulomones .
 Triple sense viz. smell , vision & hearing are so sharp due to presence
of well defined(developed) nasalaperture , eyes & ears respectively .
They make characteristic sounds .
 They may be herbivorous , omnivorous , insectivorous , carnivorous .
Relatively, crop-products & storedfoodgrains wastageis more than having
the same by them . Bandicota bengalensis , B. indica , Rattus rattus , Rattus
norvegicus , Mus musculus , etc.
 Systematic Position :-
 Phylum : Mollusca
 Class : Gastropoda
 Sub-class : Pulmonata
 Order : Stylommatophora

5.  Characters :-
 Head with two pairs of tentacle , eyes at the vertex(apical point) of
tentacles .
 Shell spirally coiled or absent .
 Respiratory organ pulmonary sac .
 Bisexual .
 No larval stage
 Usually fresh water or terrestrial .
Sometimes Gastropoda includes snail & slugs – occur economic damage or
disfigure and disrupt the flowering plants . Helix pomatia, Acatina fulica, etc.
 Systematic Position :-
 Phylum : Chordata
 Class : Aves
 Characters :-
 Body wrapped with numerous feathers .
 Mouth projects into beak or bill having an external horny sheath .
 Well-defined visual sense organ and hearing and sound producing
aids arrangement .
 Fore legs(limbs) modified into well defined wings . hind limbs(legs)
enveloped into horny skin .
 Lay , on which they sit to hatch chicks and rear them till they can
find for themselves .
 Omnivorous , grainivorous or frugivorous .
Most of them , either useful or harmless . But a few ones belong to pest
category(status) or vector of maladies in human & domestic animals .

6.  Systematic Position :-
 Phylum : Nemathelminthes
 Class : Nematoda
 Characters :-
 Body unsegmented , cylindrical and bilaterally symmetrical .
 Worm like minute animals without a true body cavity , size from 20-
30mm. in length .
 Cuticle thick and tough .
 Complete alimentary canal but without digestive gland .
 A nerve ring & ventral nerve chords constitute nervous system .
Migratory or sedentary . phytophagous(ectoparasite , endoparasite or
semi-endoparasite) or microbivorous . Whereas they may be predaceous or
saprophytic .
The injury results in various responses depending upon hosts & nematode
involved . Role of mechanical injury in producing a disease in the plant is
minor and unimportant . Almost damage is due to secretion(which may be
enzymatic) into the plant while feeding . This secretion is accumulated in the
salivery gland . It is the habit of all types of nematode to inject saliva into host
before or during feeding . Saliva has various functions depending upon habit
of organism . In case of phytophagous, saliva may aid in penetration of cell
wall and extra-oral digestion of cell contents , making them more dilute and
easier to ingest and assimilate. The saliva , being toxic proves disastrous to
plant tissue & its effects may reach even upto foliar parts , while living only in
roots . As a result of salivery action , any one or more of following responses
may appear as symptoms of disease in host –

7. o Hypertrophy & Hyperplasia : knots , galls , etc. (increase of cell in size
& number)
o Stimulation of Growth : In some cases (invasion of Meloidogyne hapla)
saliva may stimulate cell division thereby resulting in the proliferation
of organ .
o Cell Necrosis : cell death may occur due to dissolution of the cell walls
or middle lamella by saliva .
o Suppresive Mitosis : Many nematodes , even those living in the soil but
not entering the plant , feed on cells of growing root tip. Devitalization
of root tips , even in small quantities ultimately affects the growth of
entire plant .
*Distinguishes between Moth & Butterfly
ITEMs MOTHs BUTTERFLies
Egg Usually flat and round Cigar shaped and
cylindrical
Larva(Larvae) Usually covered with
hairs
Smooth and naked
Ocelli(ocellus) Two Absent
Antennae Thread/comb like or
feathery
Club shaped
Pupa Mostly enclosed in
cocoon
Naked
Body Shape Relatively large Slender
Resting position of wing Wings lie in a slanting
roof-like disposition on
either side of body
length
Wings are held over the
back in vertical position
Activity Time Usually nocturnal flier Diurnal flier

8. LIVING & FEEDING HABITs Of SOME IMPORTANT GENERA Of PLANT PARASITIC NEMATODEs
Living Habit Ectoparasite Endoparasite Semi-Endo
Migratory Xiphinema(dagger
nematode)
Pratylenchus(lesion
nematode)
None
Longidorus(needle
nematode)
Radopholus(burrowing
nematode)
Trichodorus(stubby root
nematode)
Aphelenchoides(foliar
nematode)
Paratylenchus(pin
nematode)
Ditylenchus(stem & bulb
nematode)
Tylenchorhynchus(stunt
nematode)
Criconemoides(ring
nematode)
Hemicycliophora(sheath
nematode)
Sedentary Cacopaurus Meloidogyne(root knot
nematode)
Tylenchulus(citrus
nematode)
Nacobbus(false rootknot
nematode)
Rotylenchulus(reniform
nematode)
Heterodera syn.
Globodera(cyst
nematode)