He was taught by the zoologist Ilia Mechinikov (Nobel Prize in Physiology and Medicine in 1908), the embryologist Alexandr Kovalevsky and the physicist Nicolae Oumov. Isaak Krassilchik practiced research and application of chemical pesticides, at a time of need to protect food crops from pests and to prevent the return of frequent famine in the 19th century - it was a serious concern for people and their agronomists. Through his activities in the field of pest control, Isaac Krassilchik can be considered a living pioneer. Isaak Krassilchik will focus on the fight against pests from different crops in an important place in Russian agriculture, such as sugar beet and vines. His work on methods of protection using microorganisms (now known as biopesticides) is the most original and refers directly to the pastor of modernity. This work was done in collaboration with Ilia Mechinikov and is another mi- lestone in the history of biopesticide research and development. Isaak Krassilchik was the first to study the fluffy mold of Bessarabia. This vine disease, caused by a fungus, Plasmopara viticola, appeared in France in 1878 and was then sent to Eastern Europe. Unlike phylloxera, its treatments are chemical. He will continue research on microorganisms, and in 1886 - a microorga- nism that remains today called Cercobodo Krassilstschick.