Learn English – How to express two plural nouns separated by ‘and’

In the first example, the object contains to only one process; immediate removal of pods from harvested plants (even though pods is a multiple). Therefore, is is correct.

In the second example, the object contains more than one process; protection against contact with the disease-carrying mosquitoes and mosquito control. Its more than one, so are is correct.

You aren't talking about the parties together as a unified group, but how they feel individually. You generally are always doing this when you use neither.

This may help you understand:

Neither [one] of the parties is concerned with Egypt

Usually the one is understood and left out of the construct.

I'm not sure if the below is correct, but here goes:

Let's say you had a total of four parties, and for some reason, they were afflilated in two groups, i.e. party A and B, and party C and D. Then you could say:

Neither two of the parties are concerned with Egypt.

You can see how this is confusing unless there's a strong context to help, so I would really avoid using neither in this situation, even if it is correct.