Exam practice

Honey bees live together in a large, organized colony of one queen, thousands of workers and some drones. The work is divided among them (the queen lays eggs, drones mate, workers do everything else), they communicate with pheromones and dances, and none of them can survive alone. Living in such an organized group with division of labor is what makes an insect social.

For bees, “pasture” means plants in flower. Bees eat only nectar (made into honey) and pollen, which they collect from flowers within a few kilometers of the hive. Without enough flowering crops, trees and wild plants around the hive all through the year, the bees go hungry, make little honey, and the colony weakens or flies away.

During mating in the air, the drone’s reproductive organ (endophallus) stays attached to the queen and is torn out of his body as they separate. This tears his abdomen, and he dies within minutes.

Bees serve many purposes at once: they give honey (food and medicine), beeswax (cosmetics, candles), royal jelly, propolis, pollen and venom; they pollinate crops and wild plants, raising harvests; they give farmers an income; and their teamwork is a model for people.

Three kinds: the queen (a fertile female, usually one), the workers (sterile females, tens of thousands) and the drones (males, a few hundred in the breeding season).

Its function is to mate with (fertilize) a new queen on her nuptial flight, so she can lay fertilized eggs. Drones also help to keep the brood warm inside the hive.

Without the queen’s pheromones, the workers notice within hours that she is gone. They choose a few worker larvae less than three days old, enlarge their cells, and feed them only royal jelly, so they develop into new queens (in about 16 days from the egg). The first new queen to come out kills her rivals, goes on her mating flight, and takes over the control of the hive. Until then the workers keep the hive running. If no young larva is available, some workers may start to lay unfertilized eggs, which give only drones, and the colony slowly dies out unless the beekeeper gives it a new queen.

With pheromones: chemicals made in her body (especially in glands near her jaws) that spread through the colony as the workers lick and touch her and each other. The queen’s pheromones tell the colony she is present, keep the workers’ ovaries undeveloped so they don’t lay eggs, stop them from raising new queens, keep them working together, draw a swarm together around her, and attract drones for mating.

Honey is a nourishing food that gives quick energy; it is used in Ayurvedic and home medicines (for coughs and sore throats, and on small wounds because it kills germs); it sweetens sweets, cakes, bread and drinks; it is used in cosmetics and skin care; and it is sold, giving farmers an income.

The queen is the largest bee in the hive, about 18–20 mm long, with a long abdomen that reaches well beyond her folded wings. Like all bees, her body has a head, a thorax and an abdomen. Her head is small and rounded for her size, with compound eyes, antennae and a short, hairy proboscis. Her thorax bears three pairs of legs (with no pollen baskets) and two pairs of wings that look short for her body. Her abdomen holds large ovaries, the spermatheca, glands that make pheromones, and a smooth, curved sting at the tip. She has no wax glands.

Workers clean the cells; keep the brood warm; feed bee bread to the older larvae; make royal jelly and feed it to young larvae and the queen; make wax and build the comb; seal cells of larvae and honey; make honey from nectar and fan it to dry it; guard the hive and sting intruders; cool the hive by fanning and bringing water; and collect nectar, pollen, water and plant resin. They also raise new queens when needed.

Work is divided first by caste: the queen only lays eggs and controls the colony through pheromones; drones only mate with queens; workers do all other work. Among the workers, work is divided by age, as their glands develop: days 1–3, cleaning cells and warming the brood; days 4–6, feeding bee bread to larvae; days 7–11, making and feeding royal jelly; days 12–17, making wax and building comb; days 18–20, guarding the hive; after about day 21, foraging for nectar, pollen and water until they die. The plan is flexible, so the colony can move bees to whatever work is most needed.

The honey bee goes through complete metamorphosis: egg, larva, pupa, adult (draw the cycle as in Figure 3.6).

1. Egg: the queen lays one white egg in each cell; it stands upright, then leans, then lies flat. Fertilized eggs give females (queens or workers); unfertilized eggs give drones. The egg stage lasts 3 days.
2. Larva: a white legless grub that eats constantly and molts five times. All larvae get royal jelly for 3 days; then only future queens stay on royal jelly, and the others get bee bread. It lasts 5.5 (queen), 6 (worker) or 7 (drone) days, after which the cell is sealed with wax.
3. Pupa: a resting stage with no feeding, in which old tissues are broken down (histolysis) and the legs, wings, mouthparts and adult organs are built (histogenesis). It lasts 7.5, 12 or 14 days.
4. Adult: the bee chews through the wax cap and comes out, after 16 days (queen), 21 days (worker) or 24 days (drone) in all.

Parthenogenesis: the development of a new individual from an egg that has not been fertilized.

Bees fly a few kilometers from their hive to collect nectar and pollen, visiting the flowers in all the fields around, not just their keeper’s. As they move from flower to flower they carry pollen and pollinate the crops (mustard, buckwheat, fruit trees, vegetables, pulses). Better pollination means more and fuller seeds and fruit, so neighboring farmers harvest more and earn more, without keeping a single bee.

Mustard flowers produce more and better seed when insects carry pollen between them. The beekeepers’ bees had been pollinating the mustard. When they left, far fewer pollinators visited the fields, many flowers were not pollinated or only partly pollinated, and fewer pods and seeds formed, so the yield fell. Bees and crops help each other: crops give bees nectar and pollen, and bees give crops pollination. Beekeeping therefore raises farm production, and farmers and beekeepers both gain by working together (keeping flowering plants around, and spraying pesticides only when bees are not flying).

• bee → parthenogenesis (unfertilized egg) → drone (male, haploid)
• bee → fertilization (fertilized egg) → queen (fertile female)
• bee → fertilization → worker (sterile female)