Meeting Abstract

67.5  Jan. 7  Food intake and its effects on life history in a parthenogenetic insect ROARK, A.M.**; BJORNDAL, K.A.; Univ. of Florida, Gainesville; Univ. of Florida, Gainesville

Changes in food availability throughout an animalís lifetime can influence physiology and life history. In this study, we assessed the effects of various combinations of ad libitum and restricted intake on rates of growth and development and evaluated the life-history responses to these diets in Indian stick insects (Carausius morosus). Insects were fed leaf discs cut from English ivy on one of five treatment schedules: (1) ad libitum, (2) restricted (60% of mean ad libitum intake), (3) ad libitum until the beginning of the fifth instar followed by restricted feeding, (4) ad libitum until first oviposition followed by restricted feeding or (5) restricted until the beginning of the fifth instar followed by ad libitum feeding. Intake pattern affected both age and size at each life-history transition. Although food restriction early in life extended lifespan, this longevity enhancement did not allow for compensatory reproductive output. Egg output was maximized when daily intake was maximized throughout life. These findings suggest that the beneficial effects of early-onset food restriction on lifespan were negated by the detrimental effects on reproductive output. Conversely, late-onset food restriction negatively affected both longevity and reproductive output, with reproductive output more severely affected when a food restriction was imposed during development than when it was imposed during adulthood. The present study indicates that fluctuations in food availability can significantly influence life-history traits and that the magnitude of these effects depends on the developmental stage during which food availability changes.