Priority effects of bamboo-stump mosquito larvae: influences of water exchange and leaf litter input

1. A series of laboratory experiments was conducted to examine the influences of leaf litter input and flushing of medium on the priority effects of the two bamboo-stump breeding mosquitoes, Aedes albopictus and Tripteroides bambusa , using 150-ml microcosms. Larvae of either species were introduced to microcosms on day 0 (early cohort), at different densities, and day 14 (late cohort). The effects of the early cohort on survival, pupation, and biomass yield of the late cohort were compared among various combinations of the two species and among different treatments (water exchange, leaf addition, both of them, neither of them) on days 14 and 44. 2. Survivorship and pupation success of the late A. albopictus cohort were affected negatively by the presence of either species of the early cohort to a greater extent than those of the late T. bambusa cohort. 3. Water exchange reduced mortality of the late A. albopictus cohort over a short term in the presence of the early cohort of either species, indicating that a toxic substance was involved in the inhibitory priority effects. The addition of leaf litter enhanced survivorship and pupation of the late A. albopictus cohort, whether or not water was exchanged. The late T. bambusa cohort showed high survival rate with all treatments. 4. The results indicate that leaf-litter input moderates the inhibitory priority effects on A. albopictus larvae, not only by supplying food resources but also by alleviating the toxicity of accumulated dissolved substances.