Studies on Biology and Integrated management of giant African snail, Achatina fulica Bowdich (Stylommatophora : Achatinidae)

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dc.contributor.advisorAgarwal, M. L.
dc.contributor.authorKumari, Priti
dc.date.accessioned2016-09-15T10:19:56Z
dc.date.available2016-09-15T10:19:56Z
dc.date.issued2011
dc.description.abstractPresent study envisages the results of studies conducted on various aspects of biology and management of giant African snail, Achatina fulica Bowdich. In the laboratory snail made depression in the soil before oviposition and then laid eggs with large amount of mucus while in fields eggs were laid by making a small depression on moist soil or in shady covered places under litter or debris having enough moisture. The clutch size was ranging between 125-312 eggs per clutch and hatching percentage varied between 67.50 to 79.10 per cent in different clutches. Incubation period was observed ranging between 6-21 days. The hatchability of eggs from four different egg clutches consisting of 125, 271, 210 and 252 eggs was observed as: 74.40, 67.50, 72.80, and 71.03 per cent, respectively. Brassica oleracea var. capitata was found most effectual food for snails as maximum mean gain in weight and length, i.e. 0.87 g and 0.20 cm, respectively were recorded when snails were fed on this host. Mean gain in weight and length with respect to Dolichos lablab as food was found to be lowest. At the time of hatching the snails were smaller in length (0.5 cm), lighter in weight (1.20 g) and have lesser number of whorls (2). The length, weight and number of whorls in 80 days old snail were 6.5 cm, 25.23 g and 4.5, respectively. The results indicated that availability of food had positive correlation with growth potential of the pest. Snail moved fastest on plain soil surface (118 cm in 30 minutes) in comparison to other surfaces. Distance travelled by snail on, undulated soil surface, cemented floor, Bitumen road and concrete based road was 110.0 cm, 91 cm, 82 cm and 71 cm, respectively. The snail was able to move fast on Colocasia esculenta leaf (99.0 cm) followed by on banana stem (80 cm), Hibiscus rosa-sinensis (78 cm) and Carica papaya (68 cm), respectively while restricted movement (61 cm) was observed on glass pane. Snail pest appeared one week after the first monsoon shower in 2008 and the population reached up to 19.47 snail/25 m2 in 21st standard week. The pest activity increased gradually and reached its peak in 39th standard week, i.e. 94.20 snails/25 m2, thereafter population gradually decreased from 40th standard week and decline to its lowest level (4.20 snail/25 m2) by 47th standard week. Optimum condition of good summer rainfall and increase relative humidity provided favourable environment for growth and abundance of pest. The population of snail showed similar trend during 2009 as that of previous year. Both maximum and minimum temperature exhibited a positive correlation with pest population and minimum temperature was observed to have significant influence on development and survival of snails. The combined effect of weather factors on A. fulica population was 73%. In 2009, results with respect to correlation of snail population and weather parameters were in accordance as that of previous year. The cumulative effect of weather factors on population dynamics of A. fulica was 62% in this year. The pooled data of both the years indicated that snail population had a positive and significant correlated with minimum temperature (r = 0.600 **), maximum relative humidity (r = 0.706**), minimum relative humidity (r = 0.674**) while positive but non-significant relationship with maximum temperature (r = 0.260) and rainfall (r = 0.266). The coefficient of determination R2 was 0.692. A. fulica showed clear preference for particular plant species when fed in different hosts, viz. vegetables, fruits, ornamentals, cereals, pulses, oilseeds, spices, fodder crops, etc. Momordica charantia, Allium sativum, A. cepa, Sacharum officinarum, Daucus carota, Nicotiana tabacum and Parthenium hysterophorus appeared as non host plants for the pest. Amount of food eaten by the different stages of pest was found to vary widely from one host plant to another. Among hosts, Brassica oleracea var. capitata was preferred by all size groups of A. fulica where the consumption percentage values appeared as 12.90, 14.40 and 15.13 for infant, growing and adult, respectively. Darkness provides suitable environment for feeding as food consumption was recorded much higher in dark than light condition. Among all 24 foods provided, ingestion quantity was maximum for Brassica oleracea var. capitata both in light (6.75 g) and dark (15.50 g) condition while snail consumed minimum amount of drumstick, Moringa oleifera (0.25 and 1.45 g) under light and dark conditions. The mean percentage seedling damage per snail varied widely from 4.5 in Capsicum annum to 35.80 in Brassica oleracea var. capitata indicating thereby that later proved to be most susceptible host. Handpicking was found very effective if done thoroughly on a regular basis. The mean number of snails collected per week was maximum in month of September (78.25) and minimum numbers of snails were collected in the month of November. Highest number (34.26) of snails were attracted to vegetable waste (cabbage and cauliflower leaf) while lowest number of snail (1.00) was attracted by farmyard manure. Invertebrate predators, viz. Millipede (Orthomorpha sp.), centipede (Scolopendra sp.) and vertebrate predators like toad (Bufo melanostictus) and common myna (Acridotheres tristis) were found to be capable of killing snail pest. Among mammals, common house rat (Rattus rattus) and bandicoot rat (Bandicota indica) were observed as effective predators of snail. Among botanical pesticides, nicotine sulphate (1.25%) resulted in 70% mortality after one day of treatment and 100% mortality on 4th day after treatment. Metaldehyde granules 2.5% and cartap hydrochloride 2% were most effective barriers as no snail could cross these barriers. In dipping test conducted to kill the snails, carbolic acid (0.5%) and cartap hydrochloride (0.075%) resulted in 100% mortality of snails within one hour of continuous dipping. Bait mixtures containing any one of the ingredient like: marigold juice, long gourd juice, papaya pulp, sponge gourd juice and banana pulp in addition to common ingredients, viz. wheat bran, paddy husk and jaggary were preferred by the snails. Among different formulation of pesticides tested against snail, highest kill (80%) was obtained with metaldehyde (2.5%) at 1.5 kg a.i./ha within one day after treatment. It was followed by cartap hydrochloride (50SP) at 2.0 g/L, metaldehyde pellet (2.5%) at 1.5 kg a.i. and combination of metaldehyde (2.5G) and carbofuran (3G) at 0.75 kg a.i./ha resulted into 64, 50 and 50% mortality of the pest population, respectively. After 3rd day treatment highest mortality (100%) was obtained with metaldehyde (2.5%) @ 1.5 kg a.i./ha and cartap hydrochloride (50SP) @ 2.0 g/L. Hundred per cent mortality was noted from 4th day after treatment with metaldehyde pellet 2.5% and cartap hydrochloride 50 SP at 1.5 g/ha. Taking into consideration the results obtained in the present study an integrated management approach has been enumerated to bring the snail population below economic injury level.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/76802
dc.language.isoenen_US
dc.publisherRajendra Agricultural Universityen_US
dc.subEntomology
dc.subjectAfrican snailen_US
dc.subjectManagementen_US
dc.these.typePh.D
dc.titleStudies on Biology and Integrated management of giant African snail, Achatina fulica Bowdich (Stylommatophora : Achatinidae)en_US
dc.typeThesisen_US
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