No, we have not yet looked at eggs from solitarious- and gregarious-phase desert locust. Would be very interesting to see if there are any specific pheromonal signals emitted from eggs laid around preferred desert plants by gregarising locusts.

No., egg hatching is affected by environmental conditions, especially temp.

I think there does exist some volatile pheromone for synchronised hatching. However, I did observe a similar phenomena in Uzi fly pupa!! When pupae of Uzi fly were placed individually in containesr (pupae were from the same batch of eggs, all environmental conditions were controlled) the time of emergence was different. But, when pupa were placed in groups, they had synchronised emergence! We don't know the cause, however, we predict that there may be a form of communication between the pupae ... one form may be volatile pheromones!! Others can be vibrations or something else. Interesting !