All India Network Project on Rodent Control, A P Rice Research Institute and Regional Agricultural Research Station, Maruteru- 534 122, West Godavari, Andhra Pradesh, India. E mail: raoento@yahoo.co.in
The population size of Bandicota bengalensis Gray & Hardwick was higher during vegetative growth stage of rice crop in both the seasons and both the years. Higher percentage of females was noticed almost throughout the year except during early part of the cropping season. Sex ratio of B. bengalensis showed monthly variations in relation to crop growth period and it was highest during November in Kharif. This species remains fecund throughout the year with higher reproductive activity during the reproductive phase of the crop i.e. March during Rabi and October -November during Kharif and low activity during January and from May to August. The average number of embryos per females ranged from 11.3 to 25.5 during 2006 and 3.4 to 20.5 during 2007. The existence of super pregnancy was intermittent and the super pregnant females possessed almost double the number of embryos as that of normal pregnant. The reproductive rate ranged from 0.59 to 4.70 and 0.79 to 3.81 during 2006 and 2007, respectively. Reproductive rate and productivity per female was observed high during Kharif season compared to Rabi and summer pulse period. The annual productivity per female was 74.3 and 51.1 during 2006 and 2007, respectively.
Rice, population, sex ratio, Bandicota bengalensis, reproductive activity, super pregnancy
