Longevity of kings and queens and first time of production of fertile progeny in dampwood termite (Isoptera; Termopsidae; Zootermopsis) colonies with different reproductive structures

1. We report age-specific survivorship of founding kings and queens and colony age of first production of fertile progeny (alates) of two cohorts, containing 52 and 42 complete colonies, respectively, in the primitive dampwood termite Zootermopsis nevadensis ssp. nevadensis. 2. Longevity of kings and queens was determined and compared in various experimental manipulations of reproductive structure of incipient colonies (removal of king or queen or both vs. unmanipulated pairs as controls) performed one year after pairing. Life span of reproductives was also evaluated in circumstances of interactions between young colonies, a treatment inspired by field observations of natural nest spacing and intraspecific competition between young dampwood termite colonies. 3. In our first experimental series, founding pairs survived 2-7 years ((x) over bar = 4.5 +/- 0.3 SE) after pairing. Kings lived significantly longer ((x) over bar = 4.7 +/- 0.3 years after pairing; range 2.2-7.3 years) in treatments initiated as pairs than when left as the remaining founder in the queen removal treatment ((x) over bar = 3.2 +/- 0.6 years after pairing; range 1.5-5.3 years), even though one or more female replacement reproductives differentiated within several months after queen loss. Queen life span in the absence of kings averaged 4.9 +/- 0.4 years (range 3.6-6.3 years) after pairing, not significantly different from the life span of queens living with kings. There was no significant difference between king and queen life spans in non-interaction treatments in our first experiment. Results from the second experimental series (35 colonies) are presented to date. 4. Survival of pairs until death of one mate was significantly shorter in interaction treatments compared with control colonies, suggesting that intraspecific competition between young colonies may create opportunities for replacement reproductives. 5. The first alates were produced between 1.8 and 6.5 years after pairing in our first experimental series, and between 2.4 and 5 years, to date, in the second experiment. 6. Ecological and evolutionary correlates of long life span in social insect reproductives and other animals are discussed.