The honeycreepers are threatened by recently introduced predation, competition, parasitism, degradation of habitat, and infectious disease including mosquito-borne avian malaria. One of the consequences of the invasive birds is the introduction of avian malaria. The pathogen is primarily transmitted via female mosquitoes who will pass on the disease by biting a susceptible individual after having bitten an infected individual. The main mosquito vector ("Culex quinquefasciatus") was introduced over a hundred years before the pathogen ("Plasmodium r. capistranoae"), mostly hosted by the blue-breasted quail ("Excalfactoria chinensis"). Later, two other mosquito species, the Asian tiger mosquito ("Aedes albopictus") and the bromeliad mosquito ("Wyeomyia mitchellii") were introduced to the islands. The immune system of the honeycreepers had not been exposed to avian malaria since its common ancestor existed 4 to 5 million years ago. Thus, the honeycreepers had not co-evolved with the pathogen to develop resistance as those birds on the mainland did.