Remarkable Longevity of the Chemically Defended Moth,Utetheisa ornatrix(Lepidoptera: Erebidae) and the Factors that Affect it

Abstract

Most butterflies and moths, with the exception of Heliconius, live only a week or two in their non-hibernating state. In the present study, we evaluated the longevity of the chemically defended Ornate Bella Moth, Utetheisa ornatrix, using a sample of 214 individuals from two broods. On a diet of 6% sugar water or Gatorade®, a quarter of the moths survived for one month or longer, with a maximum survival of 50 days. A glimpse into the genetic component offered by using two broods suggests that one can expect to find greater variability in longevity between different populations of this species. Males lived on average longer than females, and moths from heavier pupae lived longer than their smaller siblings. The nutrition of caterpillars, translated into pupal weight, appears to have a positive effect on the longevity of resultant adults. While it was not surprising to find that sugar played a positive role in the longevity and fecundity of adult moths, the fact that Utetheisa ornatrix can subsist solely on water for up to 36 days and that males tended to live longer than females, which is reverse of most species for which such data is available, were intriguing findings. The chemically defended nature of this species, its high fecundity (251±64 eggs in this study) paired with its habit of laying eggs in small batches, and its propensity to disperse as adults help explain why these moths evolved prolonged life spans.