author(s)
Devina S, Kennedy JS, Senthil N and Pandiyan M

abstract
Multigenerational rearing study is a useful approach in entomology, where insect biological responses are discrete and developmental rates vary from one generation to another depending on the prevailing environmental conditions and rearing host. Fitness components of a South Indian bruchid (Callosobruchus maculatus Fabricius, Thanjavur population) were studied for continuous twenty-five generations on susceptible Vigna radiata. Inherent reproductive potential of the female bruchids varied from 47.67 to 69.67 eggs during 2^nd and 20^th generations when the average max. temperatures recorded 28.59ºC and 37.33ºC respectively. Adult females exhibited shorter lifespan (11 and 12 days) compared to males (12 and 16 days) as observed from adult mortality (released for oviposition) and offspring longevity (after emergence) studies. Sex ratio was female biased (average 22.59 ♀s over 21.21 ♂s) in all the subsequent generations. Adult emergence pattern from infested seeds showed peak emergence (8.60 adults) on second day of its initiation per generation studied and declined consecutively (7.76, 6.19, 5.19 adults and so on). Bruchid fitness was strongly influenced by prevailing max. and min. temperatures (r=0.515^**, r=0.434^* for fecundity and r=-0.613^**, r=0.745^** for development) and relative humidity (r=-0419^* and r=0.423^*). This study will assist in population ecology study and enable construction of several life tables to prepare a predictive model, which can be tested against natural population fluctuations under storage conditions in order to check infestation from reaching total seed damage.