Tritium‐Determined Water Flux in The Free‐Roaming Desert Tenebrionid Beetle, Eleodes Armata
1977
Bohm, Bruce C. | Hadley, Neil F.
Tritated H₂O was used to measure H₂O exchange in field and laboratory populations of the desert tenebrionid beetle, Eleodes armata. Free—roaming individuals were monitored in natural desert enclosures. Mean total body H₂O determined istopically (TBWᵢ) was 74.5% compared to 65.9% measured gravimetrically. Water loss rates determined istopically (WLRᵢ) for beetles decreased as the summer progressed (early summer, .079 ml ° g— ¹ ° day¹; late summer, .062 ml ° g— ¹ ° day—¹). The biological half—life of tritium (T½ b) for these respective groups was 6.4 and 8.2 days. Significantly lower WLRᵢ (.032 ml ° g— ¹ ° day— ¹) were obtained for noncaptive winter beetles. WLRᵢ and T½ b values for beetle confined to artificial burrows (no food or water) were not significantly different from values for free—roaming beetles during either season. WLRᵢ for fed and hydrated beetles maintained in the laboratory under simulated summer conditions were four times higher than WLRᵢ for food and water—deprived beetles. Tests conducted on similar groups under simulated winter conditions produced no significant differences in WLRᵢ or T@2b. These data are discussed in reference to biotic and physical factors affecting H₂O flux, limitations of the isotope technique and the research design employed, and compared to published data on other desert species.
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