Social relations among females in pre- and postemergence colonies of a subtropical paper wasp,Parapolybia varia (Hymenoptera: Vespidae)

Abstract

In southern Taiwan, most colonies (13 out of 14) ofParapolybia varia were founded by multiple females. Several females were present at the founding and increased up to 25 about one week after it. Observations on 2 pre-emergence colonies (in a total of 21 h) and those on 4 postemergence colonies (in 62 h) revealed the following facts: In the pre-emergence period, the top-ranking female dominated all others like a despot. Some females attending from the founding also dominated other females who joined later. Interactions among females gradually decreased in frequency after the founding and became milder. The top-dominant rarely left the nest and monopolized most of ovipositions by physically disturbing the subordinates' attempts to oviposit. Differential oophagy was not observed even when the subordinates succeeded in laying (6 cases). After the emergence of workers, the subordinate associates gradually disappeared and the colonies became monogynous (one egg-layer or queen per colony). Monogyny was also confirmed in October on 3 big colonies which had already produced reproductive forms. Eighty-six percent of females (n=50) taken from nests of early stage containing nothing or eggs alone were inseminated and 66% of them had well developed ovaries, while 90% of those (n=20) from more developed nests containing mature larvae and/or pupae were inseminated and only 25% had developed ovaries. This suggests that the ovaries of the subordinates had possibly, though not completely, degenerated through dominance interactions.