Effects of mating status, sex ratio, and population density on longevity and offspring production of Cryptolestes ferrugineus (Stephens) (Coleoptera: Cucujidae).
The life span and reproductive rate of the rusty grain beetle, Cryptolestes ferrugineus (Stephens), were determined at different adult densities and sex ratios at 30 +/- 1 degree C, 75 +/- 5% relative humidity (RH), and with feed consisting of ground wheat plus wheat germ (4:1, w/w). The mean life spans of adult beetles were 32 weeks for adults individually isolated in separate vials, 22 to 25 weeks for adults of different strains kept one male and one female per vial, 24 weeks for a group of 30 virgin females together in one vial, 13 weeks for a group of 30 virgin males together in one vial, 14 weeks for groups with 10 males and 20 females per vial, 13 weeks for groups with 15 males and 15 females per vial, and 12 weeks for groups with 20 males and 10 females per vial. When kept one adult per vial, males and females had similar life spans; when kept one male and one female per vial, males lived longer; when kept in groups of 30 per vial females lived longer, except in the group which had a sex ratio of two males to one female; in this group life spans of males and females were the same. Females in separate vials with one male produced mean numbers of of offspring ranging from 389 for an inbred homozygous malathion-resistant strain to 514 for an outbred strain (genetically variable: GV). GV strain females in vials which had 10 males and 20 females produced a mean of 97 offspring, GV strain females in vials which had 15 males and 15 females produced a mean of 146 offspring, and GV strain females in vials which had 20 males and 10 females produced a mean of 216 offspring. The results of this study and similar studies on other insect species suggest that the life span of this insect is inversely related to the rate at which it expends energy and to injury incurred during copulation, and that oviposition rate decreases as the density of larvae and female adults increases.
White
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ND
Agriculture Canada, Winnipeg, Manitoba.
Bell
R J
RJ
D000818:Animals; D001517:Coleoptera / Q000502:physiology*; D005260:Female; D008136:Longevity; D008297:Male; D010058:Oviposition; D011156:Population Density; D012098:Reproduction; D012744:Sex Ratio; D012726:Sexual Behavior, Animal