show Abstracthide AbstractThis study performed RNA sequencing of fat body tissue from two populations of the tobacco hornworm caterpillar (Manduca sexta): a UNC-maintain laboratory colony and field population collected from eastern NC. The objective of this investigation was to evaluate the effects of diurnal temperature fluctuations (of 30 plus and minus 0, 5, or 10 degrees C) throughout development on larval gene expression both independently and in conjunction with subsequent thermal exposure (of 30, 35, or 40 degrees C). Results from differential expression analyses of these data highlight large differences in overall gene expression patterns between these two populations (across all temperature treatments) as well as population-specific transcriptomic responses to temperature. Exposure to fluctuating temperatures during rearing did alter gene expression during later heat stress in some cases, but this effect depended upon both the population and the specific temperature conditions. This research contributes to increased knowledge of molecular mechanisms underlying physiological responses of organisms to temperature, particularly with respect to thermal plasticity and adaptation in populations with different evolutionary histories.