Abstract:
In the premontane rain forests of northwest Costa Rica, patches of secondary forest
can contain high densities of large Vriesea spp. bromeliads. Such patches contain
an average of 6,470 ± 1,080 (s.e.) larvae ha-1 of the bromeliad-dwelling pseudostigmatid,
Mecistogaster modesta, ca 36x higher than larval densities that we previously
reported for adjacent primary forest. Using a new method to partition landscape
variation in populations, we show that secondary forest has higher larval
densities than primary forest because of higher bromeliad abundance (13% of
effect), greater bromeliad size (33%), and greater larval abundance in bromeliads
of similar size (54%). The last effect reflects additional effects of forest type after
accounting for differences in the quantity of larval habitat. We use surveys of prey
communities in bromeliads and adult densities in the two forest types to show that
these additional effects of forest type are more likely due to adult behaviour, not
larval resource limitation. This study demonstrates that certain areas of secondary
forest can be disproportionately important for M. modesta populations, and has
implications for estimating effects of forest loss and conversion on M. modesta.
