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The influence of temperature and grain moisture content on the intrinsic rate of increase ofSitophilus oryzae(L.) (Coleoptera: Curculionidae)

Journal of Stored Products Research
Publication Date
DOI: 10.1016/0022-474x(82)90003-0


Abstract The intrinsic weekly rates of increase ( r m) of Sitophilus oryzae (L.) living in wheat of 14 or 11.2% moisture content (m.c.) at 15, 18 and 21°C were determined both by using schedules of fertility, i.e. observed numbers of adult offspring produced by cohorts of young weevils, and schedules of adult survivorship, age-specific fecundity, i.e. egg production, and estimates of the proportion of immature stages surviving to adulthood. In wheat of 14% m.c., with the former, r m ranged from 0.0718 at 15°C to 0.4498 at 21°C and, with the latter, from 0.0737 at 15°C to 0.4154 at 21°C. Both sets of values revealed an interaction between the effects of temperature and m.c. in that corresponding values in wheat of 11.2% m.c. ranged from 0.0383 to 0.3677 with the former, and from 0.0348 to 0.3025 with the latter. Additional experiments showed that values of r m derived from survivorship and fecundity schedules for S. oryzae in wheat of 12.5% m.c. ranged from 0.0560 at 15°C to 0.3378 at 21°C. No eggs were laid at 15°C in wheat of 10.3% m.c. By contrast, oviposition, but not development, was observed at 11°C in wheat of 14% m.c. Possible causes for the differences between the values of r m provided by the two methods used in the present study and the literature are examined.

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