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

The effect of new environment on adapted genetic architecture

“…In the present study a culture cycle is referred to as a generation. The insects had been reared for over 50 generations on wheat at Reading and since the life history of S. oryzae is influenced markedly by temperature and relative humidity (Evans, 1982), the cultures and experiments were kept in a constant environment (30°C and 70 per cent relative humidity, CTH conditions). A large sample of wheat breeding insects was taken at random and transferred to yellow split-pea to initiate a new breeding population.…”

“…Prior to use, all experimental food was frozen at -20°C for one week. S. oryzae is very susceptible to grain moisture content (Evans, 1982;Holloway, 1985), so grain moisture content was equilibrated to CTH conditions prior to use (Richards, 1947).…”

Chronological Age-Grading of Three Species of Stored-Product Beetles by Using Near-Infrared Spectroscopy

“…Although these conÞdence limits are large, younger adults within the Þrst third of their life span can be easily differentiated from older adults of each species with NIRS. Although older adults of these species continue to oviposit, younger females, i.e., those in the Þrst third of their life span, oviposit at a higher rate (Birch 1945, Evans 1982, Longstaff and Evans 1983, Li and Arbogast 1991. As a result, the ability to differentiate between young and old adults can provide knowledge of population age structure, which will improve the accuracy of population growth models for each of these pest species.…”

The demography of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), submodels of age-specific survivorship and fecundity

“…The rice weevil, Sitophilus oryzae (L.), has been the subject of several demographicallyoriented studies (Birch, 1948(Birch, , 1953Evans, 1977Evans, , 1979Evans, , 1982Hardman, 1978;Longstaff, 1981a, b;Sharma et al, 1979). Birch's (1953) work embraced the broadest range of experimental conditions (13-35°C and 10-14% grain moisture content), but he published detailed data for only two of the sets of conditions employed, those for the remainder having been summarised by values of X, the finite rate of natural increase.…”

“…Depending on whether the insects were transferred to cold conditions as adults or in the immature stages, both the shape of the survival curve and the reproductive schedule varied considerably. Evans (1982) later determined the values of Xfor a limited range of conditions (15, 18 and 21°C and 11, 12 5 and 14% moisture content), and these data have been used in the present study. Hardman (1978) collected demographic data over a wide range of conditions but used only part of the data set to construct a population growth model.…”