Comparison of the effects of multiple variables on the levels of infection of the rat tapeworm, Hymenolepis diminuta, in its intermediate host, the confused flour beetle Tribolium confusum.

The interaction of the rat tapeworm, Hymenolepis diminuta, with its intermediate beetle host, Tribolium confusum, is a well-studied model system. However, there is so much variation in the methods and designs of the studies that it is difficult to draw comparisons. This study simultaneously compared several aspects of the infection protocol including beetle age, sex, density and mating status; parasite egg condition, infection environment humidity and the times for the three steps of infection: starvation, feeding and post-feeding development. Although statistically limited by low prevalence and intensity levels, we were able to detect the relative effects of the variables. The effects of these variables on prevalence (percent infection) and intensity (mean number of cysticercoids) do not necessarily correlate with each other. Egg condition, reduced starvation times, higher beetle density and longer development times reduced prevalence. However, differences in intensity were only detected with older beetles. When coupled with survivorship data, our study found that our current infection protocol is optimal for infection success. However, the results suggest extending the study to other intermediate hosts and the inclusion of additional variables.

The effects of the presence of stored product pests on the microfauna of a flour community.

AIMS: To determine the effect that the presence of some beetles have on the species of bacteria found in their flour. METHODS AND RESULTS: Bacteria were isolated from flour that either did not contain beetles, contained Tribolium beetles in different environments, or contained either Stegobium paniceum or Lasioderma serricorne. These bacteria were tentatively identified by both the gas chromatography-fatty acid methyl esters (GC-FAME) method and partial sequencing of the 16S rRNA gene. All samples contained Bacillus species including the controls, but the non-Tribolium beetles and a Tribolium beetle line known to have low benzoquinones also contained Enterococcus and Enterobacter species. Additionally an unidentified bacteria isolate in the Enterobacteriaceae was also found in the L. serricorne sample. Our results also suggest incongruent identifications when using the GC-FAME method vs sequencing. CONCLUSIONS: Certain species of bacteria can be introduced by the presence of insect pests, but the diversity of species is far less in stocks of Tribolium beetles. SIGNIFICANCE AND IMPACT OF THE STUDY: Stored product pests can alter the bacterial community. Isolated species from this study show a strong genetic relationship to each other, suggesting an isolated evolving system. A unique bacteria was also isolated. GC and sequencing methods of identification are compared.

A genetic linkage map for Tribolium confusum based on random amplified polymorphic DNAs and recombinant inbred lines.

Tribolium beetles provide an excellent and easily manipulated model system for the study of genetics. However, despite significant increases in the availability of molecular markers for the study of genetics in recent years, a significant genetic linkage map for these beetles remains undeveloped. We present the first molecular genetic linkage map for Tribolium confusum using random amplified polymorphic DNA markers. The linkage map contains 137 loci mapped on to eight linkage groups totaling 968.5 cM.

Variation in the production and distribution of substituted benzoquinone compounds among genetic strains of the confused flour beetle, Tribolium confusum.

Insects often produce chemicals, such as defensive compounds, whose quantity and distribution can affect their fitness. For evolution to produce adaptations, chemical production must be genetically variable. Here we report the results of a study using high-performance liquid chromatography to quantify two important chemical secretions of the flour beetle Tribolium confusum, methyl-1, 4-benzoquinone (MBQ) and ethyl-1,4-benzoquinone (EBQ). Our results show a distinct difference in the production of the compounds among four genetically distinct strains of T. confusum (b-+, b-I, b-IV, b-Pakistan) with an unusually high amount measured for the b-Pakistan strain. By measuring internal and external benzoquinone levels separately, we were also able to detect differences in production and distribution of the compounds between the strains. Some strains secrete more of the chemicals, whereas other strains appear to sequester the compounds within their bodies. The sexes also differ in total quinone production as well as in their internal to external benzoquinone ratios, suggesting the trait is sex influenced. Finally, a consistent correlation in the amounts of MBQ to EBQ in individual beetles suggests that the substituted benzoquinones share a common precursor or pathway.