Small water-holding containers such as abandoned tires, cemetery vases and tree holes are rich microcosms harboring communities of invertebrates including immature stages of multiple mosquito species.  These container habitats can serve as ideal model systems to study community interactions especially with relation to invasive biology.   Malathion, a common pesticide applied to control adult mosquitoes and agricultural pests, can inadvertently get into container microcosms.  Aedes albopictus and Ae. japonicus, two co-occurring and competing container mosquito species , invaded United States via tire transport from Asia. Aedes albopictus is highly invasive and vectors multiple arboviral diseases around the world. We tested the impact of low levels of malathion on: 1) interspecific competition between A. albopictus and A. japonicus and 2) intraspecific competition between lab strain and field strain A. albopictus.  

Results/Conclusions

Survival of A. albopictus decreased with increase in A. japonicus density, but this interspecific competition was absent in the presence of malathion. There was intraspecific competition among A. albopictus in control but not in the presence of malathion. These and other preliminary results from competition experiments indicate that malathion could facilitate invasion by A. albopictus. Effect of malathion was not different between lab and field strains but lab strains were less sensitive to intraspecific competition than field strains indicating the importance of using field collected specimens in community ecology experiments.