The population dynamics ofCryptolestes ferrugineus(Stephens) (Col., Cucujidae) in flour and on Manitoba wheat

Abstract

Davies (1949) found that whereas cultures of adults of Cryptolestes pusillus (Schonh.) had a high fecundity on flour or crushed wheat, on sound wheat the production of larvae was negligible and the adult mortality very high. Even when slightly damaged wheat was used, few larvae survived into the later instars. Williams (1954) confirmed that newly hatched larvae are unable to enter unblemished grains, and Bilett (1949) found this was also true for larvae of Cryptolestes ferrugineus (Steph.).Nevertheless, both species were reported (E. W. Howe and T. A. Oxley, personal communications) to be capable of attacking commercial grain when this was stored for a long period. The experiments described below were designed to elucidate the factors controlling the growth of populations of G. ferrugineus, particularly in grain. Materials and methods.The work is in five parts which are shown below as sections (a) to (e) and similarly marked in the " Eesults " (p. 365) and in the " Discussion " (p. 372). , (a) The effect of crowding on reproduction in flour.The effect of crowding on oviposition, and on the survival of eggs and larvae in flour were investigated by putting adults at six different densities on a standard environment maintained at 25°C. This environment consisted of a layer, 0-5 cm. deep, of wholewheat flour plus 10 per cent, yeast, sieved to remove large particles and conditioned to 70 per cent. E.H. In five cases it was obtained by putting 7 g. of flour in a glass tube of 5 cm. diameter and in the sixth by putting 25-5 g. in a glass jar of 9-5 cm. diameter. Adults were taken from a large mass culture maintained at 25°C, derived from the 33D culture of an experiment described later (see below and p. 368), after thorough mixing to ensure uniformity. About 60 individuals were put in the jar and in one of the tubes, and 250, 500, 1,000 and 2,000, respectively, in the remaining tubes, the cultures being named from A to F in order of increasing density. The containers were covered with muslin, but no other precautions were found necessary to keep the humidity at 70 per cent. E.H. The adults could not climb the sides of the tubes and no eggs were laid on the muslin. The containers were left for 14 days and then sieved, the eggs and larvae being counted and removed. The adults were put back on fresh flour and the process was repeated. At the second sieving, dead adults were counted as well. The living adults were returned to fresh flour and the number of eggs counted after a further four days. (b) The history of cultures of infested grain.The history of cultures of C. ferrugineus on whole wheat at 70 per cent. E.H.

Ecology of insect‐induced hot spots in stored grain in western Canada

“…SMITI.~ (1959) calculated the intrinsic rate of increase of C.ferrugineus as 0. 90 per week, or 40 times a month at 30~ The speed of its development increases with increasing temperature (AshBY 1961). The phenomenal increase in its population from February 22 to March 21 in the fully-developed hot spot (Fig.…”

The population ecology of a self‐maintaining colony of the Common frog (Rana temporaria)

“…A number of species of grain beetles are casually cannibalistic, like the Anura, and this appears to be an important mortality factor in certain circumstances (Crombie, 1944;Boyce, 1946). In the case of the grain beetle Cryptolestes ferrugineus, cannibalism and competition by a large cohort of larvae or adults has been reported to prevent recruitment of further individuals to the population from eggs in certain circumstances (Ashby, 1961). Alm (1946Alm ( , 1951 similarly suggested that the almost complete dominance over a period of several years of a single year class of perch (Percafluviatilis) in small dystrophic lakes he studied, was due to its predation on the broods of subsequent years.…”

The life-history and reproductive potential of Cryptolestes pusillus (Schönherr) (Col., Cucujidae) at high temperatures and humidities

“…E.H., eggs were allowed to hatch, the first-instar larvae being removed. No damaged eggs or other signs of cannibalism were seen at any time (see also Ashby, 1961). A considerable proportion of the eggs was laid through the muslin on to the cork where, given the opportunity, larvae readily developed in the lenticular material.…”