Controlling resource acquisition to reveal a life history trade‐off: egg mass and clutch size in an iteroparous seed predator, Prostephanus truncatus

Abstract

1. A trade‐off constraining egg production was investigated and the consequences of egg mass for the offspring life history in Prostephanus truncatus investigated. Fresh egg mass was found to vary between 0.065 and 0.109 mg (about 20% of fresh body mass at emergence) and was correlated both with dry egg mass (r = 0.8) and with the mass of first‐instar larvae (r = 0.8).2. There was a negative correlation between egg mass and clutch size: doubling clutch size from eight to sixteen eggs resulted in a reduction in egg mass from 0.09 to 0.07 mg. Resource allocation per clutch was not constant but increased with clutch size. After allowing for the relationship between egg mass and clutch size, heavier females were found to oviposit both heavier eggs and more eggs in a clutch.3. By placing eggs in prepared seeds that minimized variation in resource acquisition, it was discovered that development period of females, but not of males, was negatively correlated with egg mass. Egg size was not correlated with body size at emergence in either sex.4. The results are interpreted as revealing a resource‐allocation trade‐off in egg production.