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The scorpion Paruroctonus aquilonalis (Stahnke) was studied to better understand the influence that six potentially important factors (size, sex, temperature, nutrition, season, and humidity) have on its respiratory metabolism. Respiratory rate: temperature relations of oxygen consumption from 5°C to 36°C, and standard metabolism estimates at 20°C and 25°C were employed. Respirometry was performed on both freshly collected mature and immature scorpions and on laboratory-maintained animals.

Inverse weight: metabolism relationships were noted for males and females above 24°C, but below 24°C live weight did not influence metabolic rate among females. For mature males positive weight: metabolism patterns were found below 24 ° C due to seasonally elevated levels of oxygen consumption. Respiratory temperature coefficient (Q10) values were found to vary with live weight, demonstrating a general trend of lower Q10 with larger size.

Prolonged starvation of adult females lowered the slope of metabolic rate: temperature (R:T) curves, and also depressed standard metabolic rates at 20°C. These changes were considered as highly adaptive means of conserving energy during starvation periods.

R:T curves for scorpions previously exposed for about 2 weeks to either 10°C or 24°C differed significantly at most test temperatures. These changes, however, were probably complicated by starvation effects, so that evidence for thermal acclimation through changes in R:T curves was inconclusive.

Seasonal changes in R:T curves were found for mature females, although the adaptive significance of these changes remained unclear. For adult males collected in August, depression of standard metabolism at 20 ° C was tentatively correlated with natural starvation resulting from high locomotor activity and inadequate nutrition.

Respiratory quotient (RQ) did not change with starvation for females but did increase significantly for freshly collected mature males following laboratory feeding. Measured RQs indicated a predominant utilization of lipid as a substrate in respiration.

Oxygen consumption at 25°C under 10% and 80% relative humidity (rh) did not differ significantly for either freshly collected or laboratory starved adult males. For severely desiccated scorpions, metabolic rates were extremely high and variable at 10% rh, but decreased substantially following exposure to 80% rh.



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First Committee Member (Chair)

Clifford S. Crawford

Second Committee Member

Marvin Riedesel

Third Committee Member

David Ligon

Fourth Committee Member

James Gosz

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