Browsing by Author "Ranjan Advani"

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    Ecology, biology and control of black rat Rattus rattus in Minicoy Island
    (1984-06) Ranjan Advani
    Ecological and biological studies on the predominant rodent pest of coconut in Minicoy Island, the black rat, Rattus rattus, revealed a high level of infestation. Rats belonging to age class 111-140 g predominated the free living populations. The male: female sex ratio was 43 3: 56.8 with the more pronounced predominance of female sex in higher age groups (140 - 200+g). The average prevalence of pregnancy was 21.3 per cent, the maximum being in case of females over 171 g. Number of embryos per pregnant female and per female were S.92 and 0.93 respectively. Wooden traps and sherman metal traps were found effective in capturing adult and sub-adult rats respectively, while wire cages were comparatively less successful. With the increase in palm density/ha, a rise in rodent infestation levels and relative damages were observed. Ten times more rodents were trapped on the crowns of coconuts than at ground level, suggesting to undertake poison and trapping operations on the crowns of coconut palms rather than at ground level. Copra followed by insects and other vegetation were the preferred food items of R. rattus as revealed from analysis of stomach content. Rats infesting coconut crop in residential habitat were found to feed on paddy in storage also. Results of present studies have been compared with R. rattus populations infesing coconut fields in Pacific Islands
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    Ecology, biology and control of black rat Rattus Rattus in Minicoy Island
    (2007-02-08) Ranjan Advani
    Ecological and biological studies on the predominant rodent pest of coconut in Minicoy Island, the black rat, Rattus rattus, revealed a high level of infestation. Rats belonging to age class 111-140 g predominated the free living populations. The male: female sex ratio was 43.3: S6.8 with the more pronounced predominance of female sex in higher age groups (140 - 200+g). The average prevalence of pregnancy was 21.3 per cent, the maximum being in case of females over 171 g. Number of embryos per pregnant female and per female were 5.92 and 0.93 respectively. Wooden traps and sherman metal traps were found effective in capturing adult and sub-adult rats respectively, while wire cages were comparatively less successful. With the increase in palm density/ha, a rise in rodent infestation levels and relative damages were observed. Ten times more rodents were trapped on the crowns of coconuts than at ground level, suggesting to undertake poison and trapping operations on the crowns of coconut palms rather than at ground level. Copra followed by insects and other vegetation were the preferred food items of R. rattus as revealed from analysis of stomach content. Rats infesting coconut crop in residential habitat were found to feed on paddy in storage also. Results of present studies have been compared with R. rattus populations infesting coconut fields in Pacific Islands.
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    Ecology, status and post-natal development of the black rat infesting coconut and cacao
    (2007-02-08) Ranjan Advani
    The common Black rat, Rattus rattus wroughtoni Hinton (Rodentia: Miiridae) is a predominant pest (72.5% relative abundance) of cacao and coconut crops, along with seven other species of rodents, three species of bats and one species of shrew. The weights and measurements of head and body were significantly (P<0.01) more in males than in females. Of the total free living populations, females (54%) predominated. The highest prevalence of pregnant females, subadult populations : and high densities of R. rattus wroughtoni coincided with tne low rainfall period from September to October. Low levels of reproduction and subadult population were encountered during high rainfall periods from June to August, since rainfall had an adverse effect on reproduction of rats.
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    Rodent Pest Management in the Coconut Plantations of India and its Islands
    (1985) Ranjan Advani
    This communication deals with the results pertaining to eco-toxicological studies on rodents infesting coconut crop of South India, Minicoy island (Lakshadweep) and Car Nicobar. Extent of rodent damage and rodent species infesting coconut crop at its different growth stages are discussed. Mechanical, chemical and biological management of rodent pests of coconut has been suggested, keeping in view biological and behavioural patterns of rodents and cropping pattern Rodents are serious pests of coconut in almost all the seventy six coconut growing countries of the world including India and its islands. About 24 per cent /Toss to tender coconuts is inflicted by rodents in the coconut fields of Kerala and Karnataka (Advani; 1982), whereas, the rodent damage to coconut crop in Minicoy Island (Lakshadweep) and Car Nicobar reaches even up to 55 and 35 per cent respectively. In 1975, in Lakshadweep islands alone, the estimated loss to coconut crop was about 0 million nuts, costing about 35 lakh rupees (Shah and Subiah; 1975). Coconut being a perennial .crop provides a regular and abundant food and water supply to rodents all through the year. Its protective crown environment facilitates rodants to maintain their higher level of populations as ideal habitat is available to them for reproduction, nesting and rearing the young ones-This fact is further supported by the trap indices of rodent-populations (15.0-33.5; rodents /100 traps/24 hrs) which are much higher than rodent species infesting any other crop ecosystem or biome of India. This communication deals with the results;; obtained for .coconut-rodent species relationship and comparative efficacies of different types*of trap and rodenticides used to minimise , rodent pest problem in coconut crop of Kerala, Lakshadweep and Andaman and Nicobar islands.