Effects of partial sugar deprivation on lifespan and carbohydrate mobilization in the parasitoid Macrocentrus grandii (Hymenoptera : Braconidae)

We compared the lifespan of Macrocentrus grandii (Goidanich) adults fed a 5 0% sucrose solution at various intervals throughout their lives. Treatments included starvation, continuous feeding, feeding on the first day of life only, and feeding every second, third, or fourth day of life. Life expectan cy for starved mates and females was less than 3 d, and providing sugar dur ing the first day of life increased life expectancy by 2 d for males and 4 d for females. Life expectancy was highest when adults were fed continuousl y (14 d for males and 21 d for females) or every 2 (17 d for males and 23 d for females). The life expectancy of adults that were fed either every 3 o r every 4 d ranged between 9 and 16 d. Together, these results demonstrate that a constant supply of sugars is not necessary to achieve maximum surviv orship, and limited sugar availability may suffice to increase substantiall y the lifespan of M. grandii over starvation values. A series of anthrone t ests was used to determine levels of gut sugars, simple storage sugars ('bo dy sugars'; primarily trehalose), and glycogen over the first 6 d of fife o f female and male Al. grandii that were either fed,50% sucrose continuously , the first day of life only, or not at all. A single day of sugar feeding led to apparently maximum levels of gut sugars, body sugars, and glycogen, and parasitoids fed only on the first day of life maintained high levels of these nutrients for 1 d postfeeding. After this time, glycogen and gut sug ars decreased substantially, but body sugar levels remained essentially con stant. This pattern suggests a strategy in which gut sugars and glycogen ar e mobilized to maintain high levels of body sugars in starving parasitoids.