Have you ever wondered of replacing these synthetic pesticides for protecting plants in your kitchen garden or plants indoor from insect pests? Or, you want to live a green life, where you grow some useful trees and shrubs and use them in your daily life? If not, today I'm going to tell you about something that might be helpful for doing this. What I'm going to talk about is use of some incredible botanicals that have insecticidal property and repel insects when their extracts are sprayed over plants.
Plants of families Meliacea ranks first in consisting of more than 500 plants of insecticidal property.

 Neem, globally known as Azadirachta indica is one of the multipurpose tree of Meliacea family that possess insecticidal property among various other uses.
Neem is native to Indian sub-continent and usually tropical evergreen plant but it can also be planted in sub-tropical areas. Both seeds and leaves of Neem tree can be used to extract Azadirachtin, active ingredient and can be used in various forms like Neem oil, Neem cake, Neem kernel extract and suspension. It can be used to control a wide range of insect pests.
By 1990, researchers had shown that neem extracts could influence almost 200 insect species. These included many that are resistant to, or inherently difficult to control with, conventional pesticides: sweet potato whitefly, green peach aphid, western floral thrips, diamondback moth, and several leafminers, for instance.
In general, it can be said that neem products are medium- to broad-spectrum pesticides of plant-eating (phytophagous) insects. They affect members of most, if not all, orders of insects, including Orthoptera (such as grasshoppers, crickets, locusts), Homoptera (Aphids, leafhoppers, psyllids, whiteflies, scale insects, and other homopterous pests), Coleoptera (The larvae of all kinds of beetles—especially those of phytophagous coccinellids), Lepidoptera (larvae of most lepidopterous pests), Diptera (fruit fly, face fly, botfly, horn fly, and housefly), Hymenoptera (larvae of sawflies), Heteroptera (The "true" bugs—including many pests such as the rice bug, the green vegetable bug) and many more [ https://www.nap.edu/read/1924/chapter/6
The National Academics of Sciences, Engineering and Medicine].
Neem affect various stages of insect and affect insect vigour,  longevity and fecundity, antifeedant action, insect growth regulatory activity, oviposition deterrent, repellent action and reduction of life span of adults and intermediates formation (Larval-pupal, nymphal-adult and pupal-adult) [agmoocs.in, course on IPM].
How to use?
Preparation and use of neem extracts may vary widely. But in general, neem leaves can be used by grinding it and extracting it's juice (fresh condition) or powder (dried condition) and can be sprayed over plants mixing water according to the state of infestation. To prepare neem seed kernel extract, one can follow the procedures shown in the figure that I have attached below. It can also be used in combination with other botanicals having insecticidal property which I'll try to describe in another report.
The reason I have described only insecticidal property of neem tree is that, it is one of the promising species of Azadirachta genus and possess many other importances in human life too- health benefits, protection of stored grains, etc. As neem extract is naturally occurring chemical substance, it doesn't have any such negative impacts on other organisms and human as well.
So, Neem tree can be one of the best tree to be planted around your home or fields for pest management in eco friendly manner.
References:
agmoocs.in ( course on Integrated Pest Management)
https://www.nap.edu/read/1924/chapter/6

Source of image :https://agritechnepal.com/2020/04/neem-know-the-cultivation-techniques-health-benefit-medicinal-agricultural-uses/2615/