Recall that given any implication: a→b, we can translate this as saying
"a is a sufficient condition for b" or equivalently: "b is a necessary condition for a."
(1) For hiking to be safe (a:=q), the necessary condition (b:=¬r∧¬p) in your case is that berries not be ripe and for grizzly bears to not to have been seen in the area.
So we have q→(¬r∧¬p).
(2) However, you are explicitly told that this condition: (¬r∧¬p) is not sufficient, so you have to negate the converse of (1): you need to negate (¬r∧¬p)→q.
This gives us: ¬[(¬r∧¬p)→q].
To write the complete statement, you need the connective ∧ in between (1) and (2):
[q→(¬r∧¬p)]∧¬[(¬r∧¬p)→q].