Preliminary Evaluation of Mitigation Strategies for Avian Malaria in Hawaii Joy Liao, Michael Samuel, Oliver Elison Timm, Chunxi Zhang, Carter Atkinson, Dennis LaPointe Outline Background of Malaria System Future Malaria Impacts Alternative Mitigation Strategies Summary of Preliminary Results Background Hawaii `Akepa Hawaii Creeper Laysan Finch Nihoa Finch `Akohekohe Palila `Akiapola’au Maui Parrotbill `Akekeke`e `Akikiki `I`iwi Maui `Alauahio `Anianiau Kauai `Amakihi Oahu `Amakihi Hawaii `Amakihi `Apapane Lesser Koa Finch Greater Koa-Finch Kona Grosbeak Greater `Amakihi Oahu `Akialoa Lanai `Akialoa Hawai`i `Akialoa Lana`i Hookbill Oahu Creeper Molokai Creeper `Ula-`ai-Hawane Black Mamo Hawai`i Mamo Laysan Honeycreeper Po`o-uli Maui `Akepa Oahu `Akepa Kauai `Akialoa Molokai Creeper Oahu Creeper Oahu Nukupu`u Maui Nukupu`u Kauai Nukupu`u O`u Background Avian Malaria is a mosquito-borne disease caused by parasitic protozoans in the genus Plasmodium, strongly influenced by climate (Temperature and Precipitation) Future Malaria Impacts Key Conclusions Malaria transmission and bird abundance will remain stable for 20 ~ 30 years when infection rates will increase. Loss of disease-free high-elevation refuge. High temperature and more precipitation increase malaria infection and reduce bird populations. Malaria-sensitive species (like Iiwi) will have significant population decline and high extinction risk. Conservation Strategies Objectives: ¾Reduce malaria impacts on Hawaiian honeycreepers ¾Protect these endemic birds from becoming extinct General Strategies: ¾Improve host responses ¾Reduce mosquito larvae abundance ¾Reduce adult mosquitoes Preliminary results based on Iiwi under RCP8.5 at high elevation Alternative Mitigation Strategies Improve Host Responses ¾ Birds evolve malaria-tolerance to reduce disease mortality ¾ Predator removal to improve bird’s demographics Reduce Mosquito Larvae Abundance ¾ Control pigs to reduce larval habitat ¾ Release vector competitors – Aedes Japonicus to reduce carrying capacity of larvae Reduce Adult Mosquitoes ¾ Release sterile/GMO male mosquitoes ¾ Release Wolbachia-infected male mosquitoes Improve Host Responses Strategy ¾ Birds evolve malaria-tolerance to reduce mortality ¾ Predator removal to increase host demographics Goals ¾ If birds evolve disease-tolerance, they are infected with malaria, but mortality is reduced ¾ Predator control programs show limited improvement of female survival, and nest success Malaria Tolerance Predator Removal Limited Field Data Sources Control Program Survival HAEL APAP IIWI Nest Success HAAM HAEL APAP IIWI HAAM Vander-werf 2009 Rat Lindsey et al. 2009 Predator ns ns ns Woodworth & Pratt 2009 Predator 10~ 30% 2~ 10% 10~ 15% Knowlton Unpubli. Rat ns 0% 0% 75% Note: ns = not significant ~ 100% Predator Removal Reduce Larvae Abundance Strategies ¾ Control Pigs ¾ Release competing Aedes Japonicus Objective: Adult mosquito density will decrease due to fewer larvae Preliminary Evaluation Reduce Larvae Abundance Reduce Adult Mosquitoes Strategies ¾ Release Sterile/GMO Male Mosquitoes ¾ Release Wolbachia-infected male mosquitoes ¾ Complexities: release time/frequency, egg mortality, competition with wild males, and the number released Objective ¾ Reduce viable eggs to decrease adult mosquitoes Limited preliminary evaluation ¾ Evaluate 3 of 64 high elevation combinations Release GMO Sterile Males Releasing time: April to October, starting 2030, Egg mortality:0.95 P: percent of female mating with sterile males Summary Improve Host Responses ¾ Evolution of disease tolerance could save malariasensitive birds if it occurs early (2050) in high elevation, but we have no control. ¾ Predator removal does NOT significantly increase bird abundance (even with unrealistic large values) Reduce Larvae Abundance ¾ Provides a temporary solution, but does not solve the long term problem, unless the carrying capacity could reduce to a very small level Reduce Adult Mosquitoes ¾ Does not provide long-term solution Next … Further evaluation of current strategies Evaluation of combined strategies Evaluation of spatial management Acknowledgement USGS Collaborators: Dr. Eben H. Paxton Climate Scientists: Dr. Kevin Hamilton, Dr. Henry F. Diaz, Dr. T. W. Giambelluca Funder: USGS PICSC, NSF, USGS Biology Program