Studies on the voltine cycles of rice weevil, Sitophilus oryzae Linn. infesting stored arwa rice

K. D. Choudhary^a*, S.M. Shamim^a, S. K. Srivastava^b & M. Prasad^a
aDepartment of Zoology, Ranchi University, Ranchi, Jharkhand
^bDepartment of Zoology, Patna University, Patna, Bihar
Received 15th January, 2010; Revised 17th March, 2010

Abstract : Under the biological policies of survival and perpetuational strategies, the biology and life-cycle of stored grain pests in general and rice weevil, Sitophililus oryzae Linn. in particular display a remarkable phenomenon of completing multiple life-cycles in one year called multivoltinism (Vincent Labeyerie, 1989).
Supported by the immense potential of fecundity, rice weevil multiplies comfortably in different stored rice varieties being important edible food grain for man-kind. The present investigation has been done on the reproductive behaviour and number of life-cycles completed in one year stored Arwa rice (moisture content 13.7%) under annual seasonal variations of temperature, rainfall and hunidity (2009).
Seven generations of life cycles have been recorded through out the year except May – June overlap and November – December – January overlap when the temperature and RH were beyond the tolerance limits, the first being hyper – and the second being hypothermal regimes which set in the summer and winter stuporic diapause respectively.

.