\(M I=\frac{1}{2} M R^{2}+m x^{2}\)
where, \(m=\) mass of insect and \(x=\) distance of insect from centre.
Clearly, as the insect moves along the diameter of the disc. Moment of inertia first decreases and then increases.
By conservation of angular momentum, angular speed first increases and then decreases.