The cassava is an important food crop for people living in sub-Saharan Africa. In the 1970s, mealybug infestations destroyed harvests and people starved. A researcher who studied the mealybug in its native environment discovered a parasitoid wasp that was a natural predator. After extensive testing to determine safety, the parasitoid wasp was introduced into the sub-Saharan region with tremendous effect controlling the mealybug throughout most of Africa. This approach represented a form of

Biological control.

Explanation:

The introduction of parasitoid wasp into the sub-Saharan region in order to control the population of mealybug throughout most of Africa. This approach represented a form of biological control because one harmful organism is controlled with the help of other living organisms that feed on them. This method is environmental friendly and good as compared to chemical method of removing harmful insects.

relative dating involves things like higher layers are most recent than rocks lower in the sequence. this can be extended to the known sequence of fossils. rocks containing rabbit fossils are later than those containing dinosaur fossils.  

absolute dating methods mainly use radioactive elements that have known rates of decay and produce recognizable products. for example potassium 40 decays to produce argon. once a rock has solidified the argon is trapped. by measuring the argon and potassium0 you can get an accurate number for the age.  

some other methods are good for archaeological ages. dendrochronology involves recognizing the sequence of tree rings. the orientation of magnetized particles in baked clay can be used to date a fire.

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