Effects of Constant Temperature on Longevity of Adult Southern Pine Beetles (Coleoptera: Scolytidae)

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Abstract
We studied the periods of time that newly emerged southern pine beetles, Dendroctonus frontalis Zimmermann, lived without food at 10 constant temperatures between 10 and 41°C. Two hundred or more adults were tested at each temperature to obtain mean longevities and longevity distributions. At 10 and 12.5°C, average longevity was about 18 days. Above 12.5°C, these times decreased exponentially to about 1 day at 41°C. Females lived longer than males held at the same temperature. There was considerable variability in average longevity for replicate experiments; the causes for this variability are discussed. Longevity distributions changed from near uniform at the lower temperatures to peaked at the higher temperatures. The data were described mathematically using a two-component model. First, an exponential function described adult dying rates (inverse of mean longevities) as a function of temperature. Second, an empirical distribution function described the cumulative percentage of beetles dying over physiological time. It is noteworthy that on a physiological time scale, one temperature-independent distribution described the data reasonably well. The combined rate and distribution functions adequately predicted the percentage of mortality of a cohort over calendar time.