Black Bee: Ecological importance, distribution status, threats

Scientific Name: Xylocopa violacea               

Classification:

Kingdom: Animalia

Phylum: Arthropoda

Class: Insecta

Order: Hymenoptera

Family: Apidae

Genus: Xylocopa

Specie: Xylocopa violacea

Introduction

Black bees are commonly named as carpenter bees. They are named so because of their habit of making burrows and nesting in hard plant materials for example dead wood. There are 31 sub-genera of carpenter bees with include total 500 species. All the species are black in color but some are partially black and partially yellow or white. Due to black color these species are difficult to distinguish.

Ecological Importance

It act as important pollinator of many flowers, open or lid possessing, and obligate pollinator of flowers like purple passion flowers and Orphium which will never pollinate if carpenter bees don’t pollinate them.

Carpenter bees also possess acarinarium, a pouch on metastomal tergite, in which certain mites live in commensalism with carpenter bees. The nest of Carpenter bees also attracts woodpeckers. They bore further in the nest and feed on the larvae of black bee. It is a pest of timber. It can cause damage to the wood if the existence of bees or its nest is no eradicated or removed

Distribution Status

Xylocopa violacea is European specie but it also exists in France, Germany, Italy, Channel Islands, Worcestershire, Northampton shire, India northern areas of Pakistan and Azad and Jammu Kashmir. It is native to Europe and Asia. It is restricted to latitudes above 30 degrees in India.

Threats

Birds like wood peckers, bee eaters, shrikes; mammals like honey badgers and insects like mantises and robber flies preys upon the carpenter bees. Wood peckers are attracted by noise larvae make, drill holes in wood and feed upon the larvae of carpenter bees.

In addition to predators, the parasite flies like Xenox lay eggs in the opening of nesting tunnels of carpenter bees. The maggots of parasite feeds on the larvae of carpenter bees. However, It is one of the common specie of carpenter bees.

Other Important Facts

• Size: It is one of the largest bees in Europe.
• Other Names: It is also name as violet carpenter bee and bhanvra. It is named as carpenter bee because it makes its nests inside dead non-decaying wood by chewing wood using its strong mandibles. It makes very precise pedotrophic cells. The work of carpenter bee is as precise as of a carpenter.
• Behavior: It is solitary.
• Sexual Dimorphism: It shows sexual dimorphism as males have much larger eyes than females.
• Hibernation: It hibernates throughout the winters till spring approaches. Adults hibernate in wood in the abandoned nests in winters. Then the adults regain consciousness from hibernation as spring approaches in the months of April or May.
• Mating: After coming out from hibernation, the adults then search for their mate in late spring season or in early summer season. They also search for the nesting sites in this season._[16]
• Mating System: In genus xylocopa, two types of mating system are present:

Those species in which males have large eyes, males find their female partners while flight or they spot passing by females and then chase them to mate.

In second type of mating system, male bees release special type of chemicals to attract females that are ready to mate. This chemical is known as pheromone. Those males that can release pheromones have smaller heads and large pheromone releasing reserves of hypertrophied glands.

In specie violaceae one of the above two systems is followed. Male is seen buzzing outside the nest but it is unable to sting.

• Life Cycle: Carpenter bees life cycle consists of four stage. These are given as follows:

1. Egg
2. Larva
3. Pupa
4. Adult

The four stages of carpenter bee are completed in 2 months almost from the egg to adult.

Eggs: The eggs of black bee are large sized almost equal to the size of the adult bee itself. It is considered one of the largest insect eggs.

Nesting: It makes its nest in dead wood of plants. The nest is built by females alone. After mating, the egg laying female then make nests in the dead wood and lay its eggs here. Gravid female can use old or abandoned nests also.

Female lay eggs in cells known as pedotrophic cells which they make by using the paste of pollen grains and nectar, lay eggs and then make diaphragm in-between. Female bore half inch hole in wood and bore inside up to 2 inches. It then makes a right turn and makes tunnel 4 – 6 inches long. In this tunnel pedotrophic cells are made. Pollen and nectars serves as food for eggs. It seals the eggs from outside.

Larva: Eggs changes into larva and stays safe inside the nest. It also feeds on the paste of pollen grains and nectar. This paste is known as bees bread

Pupa: Pupa is the stage when the larva is inactive and metamorphosized into adult bee. During metamorphoses the larva stays inside pedotrophic cells as it is vulnerable during this period. It donot form cocoons.

Adult: The adult bee emerges out of cells and eats its way out of nest. It the grows till winter approaches, hibernates in over winter and then the cycle starts again.

• Stings: The male carpenter bees don’t have stings while the female possess stings. It is not aggressive in behavior but can sting when provoked to do so.
• Lifespan: Carpenter bees can live as long as three years. In each year, carpenter bee can have its 1 – 2 generations. ^[1]History of the displacement of the European dark bee (Apis mellifera mellifera) in Denmark: Journal of Apicultural Research: Vol 60, No 1 (tandfonline.com)^[2]Conservation of the dark bee (Apis mellifera mellifera): Estimating C-lineage introgression in Nordi (ipb.pt)^[3]https://portals.iucn.org/library/sites/library/files/documents/RL-4-019.pdf

Reviewed by:
Dr. Muhammad Khalid Mukhtar (Ph.D.)
University of Sargodha, Sargodha