Q.Citrus pests
I have a tangerine tree with a major thrips invasion. Actually, the fruit seems to be unaffected, but the leaves are heavily disfigured, gnarled and rough looking. I’ve heard that nematodes can be effective in eradicating them. Are there other tools as well?

Nematodes have been known to control thrip populations and these include the predaceous mite Euseius tularensis, spiders, lacewings, dustywings, and minute pirate bugs. There are chemical applications but thrips develop resistance quickly to them especially when the chemicals are used in large doses. Light doses of chemicals such as Spinosad, Kaolin, Formetanate Hydrochloride, Dimethoate, and Cyfluthrin have been shown to have some efficacy against thrips but you have to be careful that your chemical application doesn't kill the thrips natural enemies.
For more information on citrus thrips control, please visit the following link:
https://www.gardeningknowhow.com/edible/fruits/citrus/controlling-citrus-thrips.htm