In the sentence (a), is the word have used as an auxiliary or a main verb?
a) Decades of neglect have now come to haunt governments.
If I say (b), does it convey the same meaning?
b) Decades of neglect now come to haunt government.
In Present perfect tense have is used to say something which happens in past and has impact in present (http://www.englishpage.com/verbpage/presentperfect.html)
E.g. I have seen that movie.
Meaning: I saw that movie yesterday hence no point to see this movie again today.
Then what meanings do my sentences a) and b) convey? Do they mean the same thing?