Alexander Sokoloff

Comparative studies with Tribolium (Coleoptera, Tenebrionidae)—I: Productivity of T. castaneum (Herbst) and T. confusum Duv. on several commercially-available diets

Abstract Productivity (measured as the number of adult progeny produced in a given interval by a number of females) and relative developmental rates (the number of adult progeny found at specific intervals) have been determined for T. castaneum and T. confusum on a variety of different media. The media tested were flours of corn (C), rice (R), soy (S), whole wheat (W), a mixture of corn, rice, soy and whole wheat flour (M), white wheat (WW) and brown rice (BR) with and without a supplement of brewers yeast. In T. confusum the ranking of productivity on these seven media was found to be M>W>C>BR>R>WW>S in both unsupplemented and yeast-supplemented media, but the performance on all media was somewhat increased by the addition of yeast. The order of productivity on these media with T. castaneum was similar to that obtained for T. confusum, except that the response to yeast supplements was much more pronounced for all media except soy. In particular, white wheat, brown rice and rice, which must be considered “poor” media for T. castaneum in the absence of yeast, compared very favorably, in terms of productivity, with whole wheat and corn when these media were supplemented with yeast. These data are summarized in Table 6 and Fig. 1. These productivity results are supported by information obtained about the developmental rates of the two species on these media-in general, developmental rate was much slower on those media showing the lowest productivity. From considerations of the content of the flours used, the data suggest that soy is more toxic to T. castaneum than to T. confusum, and that T. castaneum requires more vitamins and/or minerals than does T. confusum. This conclusion is largely judged by the performance of the two species on white and brown rice, and their performance on yeastless and yeast-supplemented media. The data are given in Table 5 and shown in graph form in Fig. 2. It is suggested that T. castaneum may require greater amounts of leucine, alanine, and aspartic acid than T. confusum, and that T. confusum requires larger amounts of threonine, tyrosine and possibly methionine than T. castaneum.

Self-Elimination of Tribolium castaneum Following Xenocide of T. confusum

Studies of competition between synthetic strains of T. castaneum (CS) and T. confusum (CF) in corn alone and corn supplemented by yeast reveal that under the temperature and humidity conditions of the experiment CS eliminates CF in both media. While the surviving population of CS remains at a high level in corn when supplemented by yeast, it declines in number when kept in corn alone. Suspicions that this decline results from nutritional deficiencies in the case of T. castaneum are confirmed by experiments in which the two species reared in corn are fed eggs of the other species, and others in which T. castaneum reared in corn or corn with yeast is supplied pupae of T. confusum. It is concluded that these nutritional deficiencies lead T. castaneum to practice xenocide. Since in this way T. castaneum is eliminating the more efficient vehicle of conversion of corn into nutritional requirements essential to it, T. castaneum is also practicing unwitting near-suicide.

Comparative studies with Tribolium (Coleoptera, Tenebrionidae) — II: Productivity of T. castaneum (herbst) and T. confusum Duv. on natural, semi-synthetic and synthetic diets

Abstract Productivity of T. castaneum and T. confusum has been determined in the following diets: Naylors synthetic medium; corn supplemented with the amino acids cystine, glutathione, proline and tryptophan in amounts necessary to bring them to the level found in wheat; corn and whole wheat flour without any supplements, and corn and whole wheat flour supplemented with brewers yeast and vitamins. Relative developmental rates of the two species in these media were also determined by counting the numbers of adults emerging in 14-day periods. Significant differences in productivity (the number of eggs surviving to the adult stage) have been detected within a species in the different media and between species within a given medium. The Naylor medium is unfavorable for both species, and judging from relative developmental rates less favorable to T. confusum than to T. castaneum. T. castaneum performs poorest in non-supplemented media, better in media supplemented with vitamins, and the best in media supplemented with yeast. While T. confusum also shows an increased productivity in vitamin- and yeast-supplemented media, this increase is not as marked as in T. castaneum. Considering both the productivity and the developmental rates, it appears that the addition of the four amino acids to corn had a beneficial effect to T. castaneum but not to T. confusum. The two species were most productive in corn plus yeast, but this productivity was not significantly higher than in whole wheat flour plus yeast. Drawing upon the evidence available in the literature, and the present data, it is concluded that T. confusum is better adapted to utilize a wider variety of foods than T. castaneum and in order to satisfy its greater quantitative requirements for certain nutrients, this species engages in cannibalism more often than T. confusum. The result is that, when the two species are introduced into the same container, i.e. compete for food and space, T. confusum is more often eliminated than T. castaneum.

Linkage studies in Tribolium castaneum (Herbst)—XI The map position of “platinum eye” and “Spatulate”☆

Abstract (1) Data are presented to show that “platinum eye” (pte), a sex-linked recessive spontaneous mutation in T. castaneum, is located about 18 units from pygmy (py) and about 29 units from paddle (pd), and the order of these genes in the X chromosome is pte-py-pd. (2) Data are also given to establish the position of Spatulate (Spa) in the fourth linkage group of this flour beetle. Spa is an autosomal dominant with recessive lethal effects, and its interaction with Be produces a dominant synthetic lethal effect. It is located about 4 units, probably to the left of s, and the order of these genes appears to be Be-(s)-Spa-(s)-eju.

AN UNUSUAL SEX-LINKED MODIFIER-SUPPRESSOR SYSTEM IN TRIBOLIUM CASTANEUM.

1) A sex-linked gene (Mr) behaving as a modifier of red (r) in hemi- and homozygotes (darkening the red phenotype) and as a suppressor of r in the r Mr/r + heterozygote (resulting in a normal, black eye) is reported for Tribolium castaneum, and its position on the X chromosome (about 17 units to the right of r) is given. 2) A survey of the literature on eye color modifiers in other insects fails to show a similar situation in the Diptera (primarily Drosophila), Lepidoptera, or Hymenoptera. 3) As a tentative explanation, it is suggested that Mr/+ interacts with r/r to produce a black eye-color pigment, but the nature of the interaction is unknown.