CropBiotechUpdate
http://www.isaaa.org/kc/cropbiotechupdate/article/default.asp?ID=17042

Cotton bollworm (Helicoverpa armigera) is a major crop pest that feeds on over 300 hosts from 68 plant families. Due to its reported resistance to most insecticides, determining its mechanism of detoxifying these phytochemicals and insecticides is important in managing this pest. 

Researcher Yidong Wu from Nanjing Agricultural University in China and colleagues used CRISPR-Cas9 to knockout a cluster of nine P450 genes in cotton bollworm through embryo microinjection. The knockout strain was subjected to different phytochemicals and synthetic insecticides, including xanthotoxin, gossypol acetate, 2-tridecanone, coumarin, nicotine, esfenvalerate, indoxacarb, emamectin benzoate, and chlorantraniliprole. Gene expression was also determined using qRT PCR. Results showed significantly reduced survival rate of the pests with the knockout when subjected to phytochemicals and insecticides. CRISPR-Cas9 proved to be an effective approach to identifying genes involved in insecticide resistance in pests like cotton bollworm.

For more information, read the article in Nature.