Production Schedules of Males and Reproductive Females, Investment Sex Ratios, and Worker-Queen Conflict in Paper Wasps

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Abstract
The production schedules of males and reproductive females by the foundress queens and the ratios of parental investment in males and reproductive females (investment sex ratios) of successful colonies are compared for several temperate and subtropical paper wasps. The production schedules are classified into three types: males and reproductive females are produced simultaneously (simultaneous production), males are produced before reproductive females (protandrous production), and reproductive females are produced before males (protogynous production). The investment sex ratios for various species vary from about parity to a strong predominance of females. But significant combinations of the production-schedule type and the magnitude of the investment ratio are found. In four species with simultaneous production, the investment ratios are about 1:1. In five species with protandrous production, the ratio is more than 4:1, except for one species, for which the investment ratio seems to be underestimated. In three species with protogynous production, the female bias is moderate in two species and strong in one. The possible causes leading to these results are discussed. This study shows the error of using a single explanation for the investment sex ratios of annual paper wasps and the importance of a close examination of the social system of each species.