Effects of larval competition on survival and growth in Mediterranean fruit flies

1. Larval success was compared when one, two, or three egg clutches were la id in kumquat fruits (approximate to 10 ml in volume) either successively o n the same day or at the rate of one clutch per day. 2. Increased clutch density was associated with a significant decrease in l arval survival rate and non-significant decreases in larval growth rate and pupal mass. 3. Larval and pupal parameters showed significantly larger variance when cl utches were laid on successive days than on the same day, suggesting a comp etitive advantage for older larvae over younger larvae. 4. The results suggest that, in small fruit, reduced fitness due to larval competition may act against possible fitness benefits due to social facilit ation among adult females, hence reducing the likelihood of non-linear popu lation dynamics caused by processes such as the Allee effect.