Coelioxys

Systematic position: Coelioxys (Coelioxys) is a genus of insects belonging to the order Hymenoptera and the family Megachilidae. These insects are well known as cuckoo bees due to their cleptoparasitic behavior, as they do not construct their own nests or gather food for their offspring.

Biology and lifecycle: The life cycle of Coelioxys is tightly linked to that of their host, mainly bees of the genus Megachile. The female Coelioxys searches for the nest of the host bee, enters it, and lays an egg inside the cell already provisioned with pollen and nectar. Upon hatching, the Coelioxys larva uses its specialized, sharp mandibles to kill the host egg or larva before consuming the food supplies reserved for the host.

Nature of damage: Coelioxys does not directly feed on crops or damage leaves and stems. However, they are harmful in an agricultural context because they parasitise and kill populations of leaf-cutting bees (Megachilidae). These leaf-cutters are vital pollinators for numerous high-value agricultural crops, including alfalfa and various legumes.

Economic impact: The economic damage is indirect but significant in areas where managed bee populations are used for pollination. By reducing the number of effective pollinators, Coelioxys can lead to decreased fertilization rates, lower seed production, and reduced yields, particularly in crops that rely heavily on cross-pollination by wild or semi-managed bees.

Protection measures: Controlling Coelioxys requires delicate handling to avoid causing damage to the beneficial bee populations they parasitise:

• Regular inspection and cleaning of nesting blocks at the end of the season.
• Using mesh covers to prevent parasites from entering nesting sites.
• Monitoring the population ratio between hosts and parasites.
• Avoiding the use of broad-spectrum insecticides that are lethal to both the pollinators and their parasites.