Anti-insect screens protects plants by exclusion. Some nettings can also contain additives that help to increase their effectiveness against pests. Newer types of mesh netting can include optical additives such as aluminum strips for light reflection.
Anti-insect net was invented to protect crops from the damage caused by pests(such as aphids, mealy bugs, thrips, who hitefly...etc.), insect netting can prevent these insects and parasites from sabotaging crops.