CONTEST COMPETITION AMONG MACULINEA-REBELI BUTTERFLY LARVAE IN ANT NESTS

1. Caterpillars of the myrmecophilous butterfly Maculinea rebeli showe d strong evidence of contest competition when introduced at high densi ties to laboratory nests of Myrmica ants. 2. This is attributed to the direct feeding of caterpillars by workers, which select a few individ uals to nurture when food or ant numbers are limiting. It contrasts wi th published data for a congener, Maculinea arion, which has predaciou s larvae and experiences scramble competition in crowded ant nests. 3. Worker ants from two Myrmica rubra colonies (I and II) were used to f ound the laboratory nests hosting Maculinea rebeli. Nests from each so urce reared a similar biomass of Maculinea, but whereas those containi ng M. rubra I workers reared eight to ten lightweight caterpillars eac h, cultures from colony II reared half as many caterpillars, each of a bout double the weight. 4. Differences in nest capacity may be due to the different social structures of colonies I and II at the start of t he experiment.