Certain species of which one of the following organisms are well known as cultivators of fungi?

The correct answer is A, Ant. Several groups of ants, above all the leafcutter ants of the Americas, grow fungus as their food, a form of farming that began millions of years before human agriculture. Leafcutter ants of the genera Atta and Acromyrmex cut pieces of fresh leaves, carry them to underground nests and chew them into a pulp on which they grow a fungus. The ants feed on the fungus, weed out unwanted moulds and even carry bacteria that produce antibiotics to protect their gardens, while the fungus depends on the ants for food and spread. This is a classic example of mutualism, a relationship that benefits both partners. Termites of the subfamily Macrotermitinae and some ambrosia beetles also farm fungi. Option B is wrong because cockroaches are scavengers that eat almost any organic matter but do not cultivate fungi. Option C is wrong because crabs are not known as fungus farmers. Option D is wrong because spiders are predators that catch prey, mostly with silk webs, and do not grow fungi. Exam tip: fungus-farming insects = leafcutter ants, certain termites and ambrosia beetles; it is mutualism.