Final answer:
The term for the voluntary spread of food items like potatoes and tomatoes from the Americas to parts of Europe during the post-Columbus era is known as the Columbian Exchange. It greatly influenced global diet, culture, and contributed to both advancements and devastations like the Irish potato famine.
Step-by-step explanation:
The term for the voluntary spread of potatoes from the Americas to Ireland and tomatoes to Italy is part of the Columbian Exchange. This widespread transfer of plants, animals, culture, human populations, technology, diseases, and ideas between the Americas, West Africa, and the Old World followed the voyages of Christopher Columbus in 1492. The Columbian Exchange markedly changed the ways of life for people around the globe, as crops from the New World, such as potatoes and tomatoes, became staples in diets in various parts of the Old World.
Tomatoes, which became a foundational element of Italian cuisine, originated in the coastal highlands of western South America, while potatoes, which became deeply integrated into Irish food and culture, were initially American food crops. The arrival of these crops in Europe helped vary diets and supported population growth, leading to technological and societal advancements. However, the dependency on these crops also posed risks, exemplified by the tragic Irish potato famine caused by a blight on the single variety of potato grown in Ireland, which result in over a million deaths and the emigration of nearly two million people.