non insect pest

1. Slugs and SnailsASSIGNMENT
Submitted To :- Submitted By :-
Dr. O. P. Chaudhary Vaibhav
Dept. of Entomology

2. Phylum Mollusca
• 2nd largest phylum of animal kingdom.
• Includes slugs and snails.

3. Characteristics :-
• Unsegmented, without appandages.
• Mostly aquatic in habit.
• Respiration takes place through gills.
• Circulatory system is open.
• Development may be direct larvel.
• Snail posses a shell but slug doesn’t.
Mollusca

4. • Order : Stylommatophora
• Class : Gastropoda
• Without backbone.
• Asymmetrical, unsegmented and spirally coiled body.
• Hermaphrodite in nature.
• Lack of good protection against dehydration, hence
avoid direct sunlight.
• Mostly nocturnal.
• During day time, hide in moist place or under debris.
Slugs and snails :-

5. Snail secrete light
yellow SLIME and
Slugs secrete colourless
SLIME which become
Silvery after drying.
Slugs and snails :-

6. • In India, about 1500 species of land snails
occurs but the no. of species of slugs are
limited.
• Among these 9 species of snails and 12
species of slugs have been reported as pests
of ornamental plants, fruits, vegetables, and
field crops.
Slugs and snails (THE PESTS)

7. SNAILS -
• Found in different parts of world
including India and islands of the
Andaman and Nicobar group.
• Pests of paddy, vegetable, fruits and
plantation crops like banana and
papaya etc.
• Paddy crop is seriously damaged by
them in Kashmir and some parts of
U.P. and South India.
• They feed on leaves and stems of
plant.

8. Important species of snails -
• The common snail
(Helix spp.)
• Giant african snail
(Achatina fulica)

9. The common snail (Helix spp.)
• Helix is a genus of large air-
breathing land snails.
• This genus is native to Europe and
the regions around
the Mediterranean Sea.
• Helix is the type genus of the
family Helicidae.
• The best-
known species include Helix
aspersa, the common, or brown
garden snail, and Helix pomatia,
the Roman snail, Burgundy snail.

10. Biology :
• A hard calcareous shell that covers and
protects the internal organs.
• The head and foot region can be observed
when the snails are fully extended.
• When they are active, the organs such as
the lung, heart, kidney and intestines remain
inside the shell, only the head and foot
emerge.
• The head of the snail has two pairs of
tentacles: the upper and larger pair contain the
eyes, and the lower pair are used to feel the
ground in front.
• The mouth is located just underneath the head.
• The mouth has a tongue called a "radula" that
is composed of many fine chitinous teeth. This
serves for rasping and cutting food.

11. Life cycle :
• The snails produce both eggs and sperm in
the ovotestis (also called the hermaphrodite
gland), but it is later separated into two
divisions, a sperm duct and oviduct.
• Mating takes several hours, sometimes a
day.
• The eggs are usually 4–6 mm in diameter.
• After snails hatch from the egg, they mature
in one or more years.
• The size of the adult snails slightly varies
with species. H. aspersa grows up to 35 mm
in height and width, whereas H.
pomatia grows up to 45 mm.
• The life span of snails in the wild is on
average two or three years.
• The garden snail is a relatively fast snail. It
has been observed to reach speeds of up to
1.3 cm/s.

12. Giant African snail (Achatina fulica)
• The giant African snail is native to East Africa.
• Each individual has both testes and ovaries and is
capable of producing both sperm and ova.
• Although both snails in a mating pair can
simultaneously transfer gametes to each other
(bilateral mating).
• Snails of similar size will reproduce in this way. Two
snails of differing sizes will mate unilaterally (one way),
with the larger individual acting as a female.
• The number of eggs per clutch averages around 200.
• A snail may lay five to six clutches per year with a
hatching viability of about 90%.
• Adult size is reached in about six months, after which
growth slows, but does not cease until death.
• The snails can live for up to ten years.

14. Slugs -
• Feed on either dead or living vegetation.
• Live in most damp places.
• They have been observed to damage
vegetable crops and banana etc. in U.P.,
Maharashtra, Assam, and M.P.

15. Important spp. Of Slugs -
• The common garden slug
(Laevicaulis alte).
• The black/ brown slug
(Filicaulis alte).

16. The common garden slug (Laevicaulis alte)
• This species is probably indigenous
to Africa (western Africa and
eastern Africa).
• Laevicaulis alte is a round, dark-
coloured slug with no shell,
• 7 or 8 cm long.
• Skin is slightly tuberculated.
• The tentacles are small, 2 or 3 mm
long.

17. • Larger specimens are active during
the day sometimes.
• This slug can grow up from 0.5 cm
to approximately 4 cm in length in
7 months.
The common garden slug

18. The black/ brown slug (Filicaulis alte).
• Dirty, creamish, white, spongy eggs in
masses on damp soil.
• 74-80 eggs/ mass.
• Newly hatched juvenile resembling
adults in colour.
• Starts laying eggs at the age of about
8-9 months.
• Lay eggs twice a year.
• Adult is 8.0-8.5 cm in length, 1.5-2.0
cm in breadth, 7-8 g. in weight.
• Average life span of about 390 days.

19. Damage (Slugs and snails)
• They appear as sporadic pests in
those places where damp
conditions prevail.
• They may also appear on roads,
creating problem during taking
off or landing of the aircraft.
• Polyphagous in nature.
• Giant african snail is known to
feed on 227 host plants..

20. • They completely devour the small
leaves.
• Mature leaves show holes on
them.
• Mine like holes and tunnels are
bored in tubers, roots and bulbs.
• Sown seed of wheat in soil are
completely hollowed out startling
from embryo.
• Completely pericarp is eaten away
in case of tomato.

21. Act as carriers of propagules of plant pathogens -
• Spores of Alternaria sp.,
Phytopthora sp. and Fusarium sp.
found in SLIMES.
• Phytophthora palmivora (black rot
disease).
• Economic damage to crops of
cucurbitaceae(46%),
basellaceae(39%), by A. fulica.
• Damage to seedlings of
margild(97%), cabbage(75%),
brinjal(51%), spinach(48%).
Cabbage
Tomato

22. Management :
• Handpicking of snails during midnight and
both snails and slugs before dawn and after
dusk.
• Should be destroyed in 10% common salt
solution.
• Keep area free from weeds.
• Smooth copper or zinc sheets can be used as
mechanical barriers.

23. Chemical control
• Poison baits consists of 10% carbaryl 50WDP
in wheat bran.
• Spray copper sulphate (3%) @12 kg dissolved
in 400 ltrs. Of water/ ha.
• Dust 15% metaldehyde @ 50 kg/ha.
• Spray 50% metaldehyde powder @10 kg/ha.

24. Thank you 