How effective is deltamethrin in killing German cockroaches?

I found a papper published by the university of Nebraska. It can be found at:

http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1057&context=entomologyfacpub

Deltamethrin shows it to be the best choice for for most strains of German cochroaches, though it is the least effective for the Ectoban-R strain, chlopyrifos semming to be the best for it.