PRIORITY EFFECTS IN TEMPORARY POOLS - NATURE AND OUTCOME OF MOSQUITO LARVA TOAD TADPOLE INTERACTIONS DEPEND ON ORDER OF ENTRANCE

1. We tested for the importance of priority effects on the interaction s between immatures of the mosquito, Culiseta longiareolata, and immat ures of the green toad, Bufo viridis, the two most abundant species of many temporary pools of the Negev Desert, Israel. Previously, we repo rted that when these two taxonomically distant species were placed tog ether as early stage larvae, they competed strongly and when Culiseta larvae had the size advantage, they preyed on Bufo hatchlings. Here, w e tested the interaction between these two species in artificial pools when Bufo enters first and develops prior to Culiseta entering.2. We also tested for intra-specific competition and for the impact of both mosquito larva and tadpole on invading species. 3. We assessed these i nteractions by experimentally manipulating various combinations and de nsities of Bufo and Culiseta. We introduced early stage Bufo larvae 12 days prior to introducing first instar Culiseta larvae. 4. Bufo exhib ited a strong intraspecific density-dependent effect: tadpoles were sm aller and reached metamorphosis later at the higher density. We did no t demonstrate an intraspecific density-dependent effect in Culiseta. 5 . Culiseta larvae affected neither survival nor development rates of t he larger Bufo. Early stage Culiseta larvae were vulnerable to predati on by the larger Bufo but later instar Culiseta larval were no longer vulnerable. Bufo reduced larval development rate of Culiseta but did n ot affect pupal size. 6. Bufo tadpoles virtually eliminated, and Culis eta larvae strongly reduced, the number of individuals of an invading ceratopogonid midge species reaching the pupal stage. 7. The work here , combined with our previous work, demonstrates the importance of prio rity effects with respect to the outcome of competition and intraguild predation.