On the polymorphism and polyphenism of Automeris io (Lepidoptera: Saturniidae) in north Florida.
Keywords:phenotypic plasticity, genetics, environment, univoltine, bivoltine, organismal ecology, inbreeding, aberration
AbstractRaising field-collected batches of Automeris io eggs and larvae in north central Florida and further breeding the resulting lines in the lab for over three years yielded over 200 highly variable specimens. The polymorphism and seasonal polyphenism in male coloration are illustrated and analyzed. Expression of the rose or tawny-orange ground color of the forewing is shown to be provoked by the diapause, as was previously suggested by others. However, it was found that this expression is not clear-cut and is determined by the genetics of the parental stock and of the individual moth, and seems to be linked to the propensity for diapause and to the diapause duration. Gainesville, north-central Florida, where the study was conducted, appears to be in a transitional zone between the more northern subspecies A. io io and the more tropical A. io lilith, and both are present here, expressing not only different phenotypes, but also different phenotypic response to diapause. During the breeding experiments, A. io underwent two generations per year when kept at the natural light cycle, with two emergences, one in April-June and another in September-November, followed by a winter diapause. Many of the pupae from the summer generation broods went into diapause instead of emerging in the fall, which, in nature, should reduce the risk of mortality for the whole brood. The diapause can be eliminated in the fall generation in most (though not all) individuals by raising larvae at 24 hour-light cycle.