Meeting Abstract
P2.183 Monday, Jan. 5 Parabolic Effects of Atmospheric Oxygen on Body Size, Development Time, and Growth Rate in Zophobas morio, the Giant Mealworm FORD, C. F.*; VANDENBROOKS, J. M.; HARRISON, J. F.; Arizona State University colleen.ford@asu.edu
Changes in atmospheric oxygen over evolutionary time have been hypothesized to be important in controlling maximal insect body size. Previous investigations using fruit flies and mealworms have shown that decreases in atmospheric oxygen cause linear decreases in body size. Hyperoxia (40% oxygen) has had no effect or slightly increased size in these species, but it is unclear whether the relationship between oxygen and size above 21% is linear, parabolic, or flat. We measured the effect of rearing oxygen level (10, 21, 25, 30, 40, and 60%) on the growth and development of Zophobas morio (the giant mealworm) in both solitary and crowded conditions. Atmospheric oxygen had a strong parabolic effect on body size, growth rate and development time on individually reared mealworms, with the optimal oxygen level being 30%. At 30% oxygen, these mealworms grew the fastest, reached the largest size, and attained adulthood in the least time. These data suggest that at oxygen levels below 30%, oxygen delivery limits metabolism and growth, while at higher oxygen levels, oxidative stress inhibits growth. One factor in studying the effects of oxygen on development in mealworms is that it is know that they have higher juvenile hormone levels, additional juvenile instars, and reach larger sizes when reared under crowded conditions. So the question becomes – Do crowding and high oxygen together produce superworms, or are similar maximal sizes obtained when crowding and hyperoxia are combined? Crowded mealworms were larger at 10, 21 and 40% oxygen, but had sizes statistically indistinguishable from solitary mealworms at 25, 30 and 60% oxygen, suggesting that hyperoxia and juvenile hormone are not additive effects, but may affect mealworm development by a similar mechanism. This research has been funded by NSF IBN 0419704 and DOD 3000654843.
