(A1) heat induction.
1. pick 4~5 L4s and put them into new NGM plates (4~5 plates).
2. Put the plates at 30 degree incubator for 4~6 hours.
3. place the plates into 20C or RT.
4. at best, you’ll see males in ~2% of F1s.
(A2) heat induction with less time
1. pick ~5 L4s and put them into new NGM plates (~8 plates).
2. put the plates at 34 C for 2 hours (air incubator or water bath with parafilm and a weight both work)
3. continue as in (A1)
(B) Ethanol induction.
1. put mid to late L4s into M9 with 7~10% ethanol for 30 minutes.
2. put them back to NGM plates.
3. at best, you’ll see males in ~2% of F1s.
reference:
http://www.wormbook.org/wli/wbg14.5p52/