The mosquito race. B/c that race is estimated to have been a vector-cause of 50% of human suffering unto death.
Btw, race based on color is a canard. A better metric might be: what nation(s) have done the most good/bad. E.g., England or UK, United States, and Israel have accounted for a majority of Nobel prizes, Field prizes, for internet, industrialization, etc. If one looks to current science, individuals from Republic of China and People's Republic of China are contributing significantly to U.S. science and research. If one looks to improvements in wealth, as raising millions from ~ poverty to comfortable/middle class income, India and China have excelled in recent decades. Germany and France continue to contribute to philosophy.