"Manufacturing several hundred thousand gallons of the new fuel required the petroleum byproducts Shell normally used to make its Flit insecticide, causing a nationwide shortage of that product that year."
I can’t verify that exact claim, but as a chemist, it wouldn’t be surprising. Pesticides are mostly organic (carbon containing) compounds and oil is often used as feedstock.
So I could see some key starting material for the pesticide being diverted to make a fuel component.
"According to one source, some raw material (possibly the solvent) used for the production of FLIT was similar to that used for LF-1A fuel for the Lockheed U-2 high altitude reconnaissance aircraft, causing a nationwide shortage of bug spray in 1955. Fuel LF-1A was produced by Shell.[6]"
According to Wikipedia, FLIT was a product and large consumer-facing brand of Standard Oil, not Shell.