Why you need a mixture of two endoparasitic wasps including Aphidius colemani and Aphidius ervi. they can reduce the crop damage by parasitizing and killing a mixed population of a variety of host species of aphids that are responsible for the crop damage.
In the major cities of the Midwest and Northeast, they found relatively high paying jobs in meatpacking plants, shipyards, and steel mills. The second significant cause of the Great Migration was the desire of black Southerners to escape segregation, known euphemistically as Jim Crow.
What were the causes of the growth of mercantilism? There are several reasons why the system of mercantilism became a growth orientated. The three major reasons were the following: A. Colonialism expanded, thus creating ne â¦ w export and raw material resources; and B. The ability of home country industries to stay up to date with manufacturing technologies; and C.