If 100 fruit flies die in a laboratory population of 1,000 during a month, the death rate in the population is ________ individual per fruit fly per month:

0.1

The correct answer is Option (1) -0.1

A population has certain attributes whereas, an individual organism does not. An individual may have births and deaths, but a population has birth rates and death rates. In a population these rates refer to per capita births and deaths. The rates, hence, expressed are change in numbers (increase or decrease) with respect to members of the population.

If 100 fruitflies in a laboratory population of 1000 fruitflies die in a month then the death rate of Drosophila is 100/1000 = 0.1 individuals per fruitfly per month.

Death rate = (Number of deaths) / (Total population)

In this case:

Death rate = 100 deaths / 1000 Drosophila

Death rate = 0.1 deaths per Drosophila per month