Life Cycle and Growth of Senita Moths (Lepidoptera: Pyralidae): A Lepidopteran with Less Than Four Instars?
Holland JN. 2003. Life Cycle and Growth of Senita Moths (Lepidoptera: Pyralidae): A Lepidopteran with Less Than Four Instars?. Ecology and Population Biology. 96(4):519-523
Despite great variation in instar number among Insecta,no Lepidopteran has been observed to have less than four larval instars. I report in this work on the life cycle and growth of the senita moth, Upiga virescens Hulst,which forms an obligate pollinating predispersal seed-eating mutualism with senita cacti (Lophocereus schottii Engelmann) in the Sonoran Desert of North America. From 1996 to 1999,I studied larval growth and life cycle associations of U. virescens with L. schottii in the Þeld by labeling cohorts of eggs laid in ßowers and following them through pupation. All life stages of U. virescens were associated with ßowers,fruit,or cactus stems of L. schottii. Among the Þve cohorts studied,larval growth consistently conformed to Dyar's rule. Only three larval instars were identiÞed among the 500 larvae for which head capsule widths were measured. I discuss and dismiss the feasibility of a fourth undetected instar. I then discuss selection pressures that may have contributed to the evolutionary loss of an instar,including a time and/or size constraint on larval growth,as well as the nutritional quantity and quality of larval food.
- Type
- Journal Article
- Authors
- Holland, J
- Units
- ORPI
- Keywords
- Dyar's rule, Life History, plant-insect interaction, Upiga virescens