High incidence and feeding damage by the Giant African Snail in Andhra Pradesh
- Indian Entomologist
- Oct 13
- 5 min read
by N.B.V. Chalapathi Rao, S. Srinivasa Raju, G. Amrutha Veena and B. Govindarajulu
The Giant African Snail, Achatina fulica (Phyllum: Mollusca; Order: Stylommatophora; Family: Achatinidae) a native of East Africa, is the largest land snail and is among the 100 most invasive species in the world . The A. fulica is the most ecologically damaging land snail and the Global Invasive Species Database has ranked it among the “100 Worst Alien Invasive Species” (Invasive Species Specialist Group, 2012) and its host range includes 500 plant species. The introduction of A. fulica outside its native range dates back to the early 1800’s, when it was spread to Ethiopia, Somalia, Mozambique and Madagascar. The first occurrence outside Africa was in West Bengal (India) through Mauritius in 1847. In Andhra Pradesh A. fulica snail was first reported in coffee plantations during 2003 at Araku valley zone of Andra Pradesh. This snail was supposed to spread to various parts of India through horticultural trade.
This snail is nocturnal in nature , attacks and feeds on various horticultural crops ie., cauliflower, cabbage, tomato, chillies, beans, leafy vegetables , tuber crops, ginger, turmeric, banana, papaya, citrus fruits and ornamental plants causing significant crop damage. They are capable of devouring entire nurseries overnight with their intense feeding habit. It can grow upto a length of 19 cm and weigh as much as 750 gm. At present he giant African snail incidence is being reported from many parts of Andhra Pradesh and its severe incidence was earlier reported in 2022 in East Godavari district where its damage was observed on nurseries and vegetables. In 2025 high incidence of snail damage in 100 acres was observed on various Horticultural crops with high intensity reported in Gangareguvalasa village of Komarada mandal, Parvathipuram Manyam district. Subsequently the damage by snails on various crops was reported from Vishakhapatnam, West Godavari and Palnadu districts of AP . A diagnostic visit was conducted along with Department of Horticulture and line Departments in Gangareguvalasa village of Komarada mandal, Parvathipuram Manyam district in one acre where mixed cropping of guava, papaya, chrysanthemum and arecanut was grown having high incidence of snail population. The pest incidence and feeding damage was also observed in nearby farmers’ fields where cotton (grown in one acre) and oilpalm (grown in one acre) are also present.
Extent and nature of damage by Gaint African Snail in the field on various crops present:
Papaya: severe on ripened fruit, tender leaves and inflorescence and aggregation on tender leaves and inflorescence
Guava: Fresh flush and young leaves scraped leaving notch-like margins on leaves and slime trails on branches. leaf area loss.
Arecanut (Vegetative stage): Low to moderate injury is observed on arecanut plants.
Chrysanthemum: damage is observed on young foliage.
Very severe damage was observed on tender leaves, flowers and ripen fruits of papaya and Low to Moderate damage was observed on tender stages of guava, chrysanthemum and arecanut.
Probable reasons for high incidence and associated feeding damage
Biology : The snails are hermaphrodites and have a very high reproductive capacity , Hatched snails become mature adults in 6 to 12 months and remain fertile for 400 days. A snail lays up to 100 and 500 eggs during the first and second years, respectively and may live up to 5 years, yielding a total of up to 1,000 eggs in its life time resulting in very high population build up over a period of time
Congenial weather conditions: Consecutive monsoon showers with overcast conditions have created persistently moist soil and leaf litter creating ideal conditions for snail reproduction, movement and feeding.
Shelter sources: Thick weeds, groundcover mulches and shaded bunds are providing day-time refuges in the above field.
Irrigation timing: Drip irrigation and basin mulching with maize cobs has provided ideal conditions for the snails to rest and breed actively in the season
Ideal crops : The infested field is densely intercropped with various horticultural crops with papaya being the main crop. Tender tissues in papaya and chrysanthemum, soft guava flush, and young arecanut seedlings provided continuous succulent feed for snails to breed
Lack of Natural enemies: Low predation pressure by birds, or amphibians in the field
Management measures suggested
Remove/weaken refuges: Removal of weeds with root system, remove farm debris from the field and keeping the field clean.
Irrigation: Irrigation should be scheduled during day time as per recommended schedules .
Hand collection: The snails have to hand collected and later placed into buckets with 5% salt solution which can cause its mortality
Metaldehyde pellets (2.5–4%): Apply the pellets which are commercially available in the late afternoon or evening, when snails are most active. This is especially effective after rain or during humid, overcast weather, which are prime conditions for snail movement at recommended rates (commonly 5–10 kg/ha). It is important to ensure to keep children, pets, and other domestic animals away from treated areas, as metaldehyde is highly poisonous if ingested in non target animals.
Jaggery/bran lure + labeled bait: where pellets are scarce, baiting with a mixture containing 25 kg of rice bran, 100 gm thiodicarb, 3 kg of jaggery and 100 ml castor oil can be attempted
Low cost management measures like using tobacco stalks (50 gm )boiled in 1.5 litres of water and reducing its content to one litre and mixing it with 60 g copper sulphate dissolved in one-litre water and spraying the solution . If tobacco stalks are not available spraying with copper sulphate solution alone can be taken.
Use salt water drenched gunny bags in field boundaries to act as barrier for snail movement.
Coordinated and community based management measures have to be taken up by all the farmers in the affected area to arrest the spread and to have successful control
In the present field the farmer adopted snail management tactic which included spraying with Copper (Chelacop @ 1.5 g/L) along with micro nutrient mixture containing Iron, Magnesium, and Sulphur (Ferromag @ 2 g/L). This spraying helped in snail detachment and their fall immediately from affected plants with a 30 % mortality being observed. The remaining snails which were dislodged were later handpicked with gloves and placed in salt water solution leading to its successful annihilation in a short time. He also adopted the use of salt water drenched gunny bags in field boundaries and placing of metaldehyde pellets on a limited scale
Safety measures to be followed during snail management
Use only pesticides/baits registered for mollusc control only.
Keep baits away from children, livestock, water channels.
Use hand gloves while hand picking the snails as the secretions of African snails is capable of causing diseases in humans and wash hands thoroughly after the picking operation.
About the authors:
N.B.V. Chalapathi Rao, Principal Scientist (Ento) & CPRO, HIC, Dr. Y.S.R. Horticultural University (DRYSRHU).
Email: drysrhumuseum@gmail.com
S. Srinivasa Raju, SMS(Horticulture), KVK, Rastakuntabai, Acharya N. G. Ranga Agricultural University (ANGRAU).
G. Amrutha Veena, SMS (Plant Protection), KVK, Rastakuntabai, Acharya N. G. Ranga Agricultural University (ANGRAU).
B. Govindarajulu, Director of Extension, VR Gudem, Dr. Y.S.R. Horticultural University (DRYSRHU).
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