Question

Cochineal insect has been used in checking the wild growth of
A. Opuntia
B. Eichhornia
C. Aphids
D. Screw worm

Answer 1

Hint:-Cochineals are scale insects. They are small, soft-bodied, flat, oval-shaped sessile bugs and belong to the Order Hemiptera (Suborder Sternorrhyncha). They exhibit a clear sexual dimorphism. They are native to tropical and subtropical South America, and North America.

Complete step-by-step solution:-
Cochineal insects are plant sucking insects and help in pollination. They are considered economically important pests. They are commercially reared to obtain a pigment used as a natural dye. They are also one of the important biological pest control agents.
They behave as natural enemies of prickly pear cacti. They infest the common prickly pear, Opuntia ficus-indica (Lamarck) Miller. Opuntia is considered an invasive species in many parts of the world and causes a massive weed problem. Dactylopius opuntiae (Cockerell)) is a wild cochineal most commonly used for the biological control of Opuntia. It shows aggressive behaviour to many Opuntia species.
So, the correct answer is option (A), Opuntia.

Note:- Cochineal insects secrete an acid called carminic acid to ward off predators. This acid also known as cochineal imparts a crimson colour which acts as a natural dye. People cultivate both Opuntia and cochineal insects to harvest the insects for dye making. Insects are scrapped from the leaf pads of Opuntia. They are dried, pounded and boiled in chemicals to extract the cochineal in and mixed with aluminium to prepare the carmine or scarlet dye. Earlier, cochineals were harvested mostly for extracting dyes but with advent of synthetic dyes their use as colouring agents nearly decreased. Now, they are mostly used as colouring agents in cosmetics and beverages.