The reproductive flight phenology of a neotropical ant assemblage


Michael Kaspari, 730 Van Vleet Oval, Rm 314, Department of Zoology, University of Oklahoma, Norman, OK 73019-0235, U.S.A.


1. Alate flights reflect an ant colony's investment in sexual reproduction and dispersal yet little is known about community-wide patterns of alate phenology. Two Malaise traps (for 2 years) and two light traps (for 1 year) were used to explore the flight phenologies of 22 common neotropical species from Barro Colorado Island, Panama.

2. The traps caught 23 182 individuals and 286 species/morphospecies. The two trap methods shared only 18 species. Samples also differed in sexual composition: light trap samples were 80% female, Malaise trap samples were 2.6% female.

3. Of 22 common species, all but one flew over half the year, with about half flying every month of the year. These data, combined with a literature review, suggest a latitudinal gradient in alate flight season: one north temperate assemblage (42°N) averaged 1.6 lunar months per species. The ever-warm tropical year provides a larger flight window that allows a diversity of phenologies, from continuous to strongly pulsed.

4. Rainfall was correlated with alate flights in one-third of the species. Quantile regression suggested that high weekly rainfall was necessary but not sufficient to produce alate flights in about a quarter of the species.

5. By decreasing the number of nests releasing alates on a given day, long flight seasons may lower the probability of finding a mate. At the same time, long flight seasons may increase the opportunity of finding vacant nest sites. High population densities and high incidence of nest disturbance in this community may ameliorate the first cost while enhancing the second benefit.