This document discusses slugs and snails, which are molluscs that can be agricultural pests. It describes their characteristics, such as being unsegmented and having an open circulatory system. It provides details on common species of snails, like Helix spp. and the giant African snail, and their life cycles. Common species of slugs, such as the common garden slug and black/brown slug, are also described. Slugs and snails can damage a variety of crops by feeding on leaves, stems, fruits and more. They can also spread plant pathogens. Control methods include handpicking, using barriers, and chemical controls with substances like carbaryl and metaldehyde baits or sprays.

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 