tiny black insects in chilly and lady finger plants | Plant diseases | Commercial Hydroponics farming in India

Hello

My lady finger and chilly plants are totally affected by tiny black color insects. They are seen more in the buds and under the leaves. I tried applying need oil based pesticide with water + soap powder, but no improvement.
Also, my bottle guard plant flowers nicely and I could see tiny bottle guards coming out, but within a week they are becoming yellow and dying. Please suggest a solution.

Regards
Padmapriya