Hawaiian honeycreepers, which are closely related to North American finches, hav

Question

Hawaiian honeycreepers, which are closely related to North American finches, have been devastated by the introduction of mosquitoes and now survive only at sufficiently high elevations which are devoid of mosquitoes. Given what you know about the potential problems with introduced species, why have mosquitoes been so detrimental to Hawaiian honeycreepers when birds all over the world have been exposed to mosquitoes with little or no negative consequences?

A. Hawaiian honeycreepers have only recently evolved (branched off) from the ancestral finch stock and therefore have not had time to evolve defenses against other organisms in their native habitats

B. Hawaiian honeycreepers are competing with mosquitoes for food, and the more aggressive mosquitoes are outcompeting the honeycreepers.

C. Mosquitoes are not native to Hawaii and hence Hawaiian honeycreepers have evolved no defenses against the diseases that mosquitoes transmit.

D. Mosquitoes are more abundant on Hawaii than anywhere else on earth due to the tropical trade-winds and moist conditions.

Explanation / Answer

The correct answer is option (C) which states that mosquitoes are not native to Hawaii and hence Hawaiian honeycreepers have evolved no defenses against the diseases that mosquitoes transmit ( vectoore for avia malarial parasite).

The insects were introduced on the Hawaiin islands about two centuries back and are responsible for harbouring the parasite responsible for avian malaria which is detrimental to the honeycreepers on the islands. Since the birds have not been exposed to the mosquito avian parasite earlier, they have not evolved defenses against the parasite which has resulted in detrimental effects to the Hawaiian honeycreeper population. Therefore, these indigenous  birds evolved far away from either mosquitoes or avian malaria, and as a result many of them have little to no resistance to the disease. As a result , most of Hawaii’s remaining native birds have retreated to high, cold elevations where mosquitoes cannot survive.

However, climate change is warming the mountain habitats and making them more hospitable to mosquitoes and the deadly avian parasite that they carry. Infact, the mosquito invasion on the island is so bad that it has already resulted in the extinctin of a few species of honeycreepers and in future may completely wipe out the indigenous honeycreeper populations.

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