Dr. James Tumlinson and colleagues at USDA, Gainesville Florida USA did much of this work at least 20 years ago. They were looking for plant defenses to being chewed upon by moth larvae that secrete anti-feedants. It is on RG. look for Volicitin. beet armyworm larvae oral secretions. another link doi:10.1016/j.febslet.2007.01.067
Thanks a lot @Abhiskek Raj and @Prof. David Arthur Carlson, for kind feedback.
Actually I'm searching the method by which I can collect Diamondback moth larvae (first instar and third instar oral secretions, which is very small as compared with beet armyworm larvae).