The Society

Francis L. W. Ratnieks

Department of Biological & Environmental Science

University of Sussex

Laboratory of Apiculture & Social Insects

Social Insects: C1139

Aims and Objectives Diversity of colony life cycles in eusocial Hymenoptera How colonies are founded Stages in the colony life cycle Swarming in Honey bees

Eciton army ants

Diversity of colony kin structure

Number queens Number fathers per queen

How Colonies Are Founded

The Big Picture Colonies can be founded in various ways

Single queen

Multiple queens

Queen(s) + workers (budding, swarming)

Parasitically

Single-Queen-Founded Nests

Digging In After Shedding Wings

Seed harvester ant queen from Arizona, Pogonomyrmex, founding nest. The queen uses her wings to fly from her natal nest on her nuptial flight, but snaps them off when she starts nesting.

Claustral Colony Founding in Atta

Above. Atta queen with her wings. Left. Founder Atta nest. The queen has taken some fungus garden from her natal nest with her so she can found a new garden in her new nest.

Claustral Colony Founding Claustral: confined

Most ants but not in bees and wasps

Queen mates, then snaps off wings and establishes nest

Rears first workers using body reserves (fat, flight muscles)

First workers often very small (nanitics or minims)

Semi-Claustral Nest Founding In the Australian bulldog ant, Myrmecia regularis, the queen does leave the nest she is founding to forage for insect prey to feed her brood.

Mischocyttarus Wasp Nest, Brazil Vespinae Founder Nest

Cross section of nest being constructed by a Vespinae wasp queen. The nest, even at this stage, is enclosed. In Polistes and Mischcyttarus wasps (Polistinae), the cells are not enclosed.

Mischocyttarus Founder Nest Nest being founded by a single Mischocyttarus wasp queen. Mischocyttarus are Polistinae paper wasps, and are closely related to Polistes wasps.

Multiple-Queen-Founded Nests

Honey Pot Ant Myrmecocystus mimicus Number of Co-Foundress Myrmecocystus Queens

Number of co-foundresses in 3 years, and close spacing of new nests.

Myrmecocystus Foundress Associations Lower right. A foundress association of Arizona honeypot ants, Myrmecocystus, with 2 or 3 queens produces many more workers than one with one queen. However, having more than three co-founding queens does not seem to help.

Two Polistes foundresses In some wasps like Polistes and Halictidae bees there are often two or a few foundresses. They are usually sisters and one is dominant, doing most of the egg laying, while the other is subordinate and does most of the risky foraging. Remember, Polistes do not have a morphological queen caste – but here is behavioural specialisation

Colony Life Cycles

From Oster & Wilson 1978

Nests Founded by Queen & Workers

Budding In many ants Daughter colony is close beside the parent colony. Budding often occurs in colonies than have multiple queens. Example: Formica wood ants. In some locations there may be many colonies (ant hills) with visible trails between them. Honey Bee Swarming

Small swarm of Apis mellifera, c. 5000 bees, in a bush.

Mother queen and 2/3 workers leave nest in “prime swarm” Swarming season is April-June in England Settle in Bush Scout out nest cavities (use of waggle dance)

Chose one and move in Build wax combs use wax from glands

In original nest 10-20 queen pupae One young queen will inherit the original nest Zero to a few young queens may leave in “after swarms”

Honey Bee Swarming Swarm Founded Wasp Nest

This is the recently founded nest of the a Brazilian wasp Protopolybia (Vespidae: Polistinae: Epiponini). It is being build on the underside of a banana leaf. The wasps build a comb then cover it in an envelope.

Other Founding Strategies

Other Founding Strategies Nest usurpation: steal nest being founded by conspecific queen

common in Vespinae wasps and Bombus

Workerless parasitic species Take over nest founded by another species Workers of other species rear your brood

Vespula austriaca takes over Vespula rufa V. a. mandibles designed for fighting not working

Temporary social parasites Many ant species Species has workers but queen enters nest of another species to found her nest

Colony Life History

Annual & Perennial Colonies Annual

Founded in spring by queen(s) Dies in late summer or autum that year Produces workers then queen & males Inseminated queens overwinter Vespinae, Polistes wasps, bumble bees, Halictidae bees

Perennial Can live for more than one year Usually produces queens & males in more than one year ants, termites, honey bees, stingless bees, Epiponii

Book by Oster & Wilson 1978

Stages in life history of a generalized ant colony. From Oster & Wilson 1978. F = founder, E = ergonomic, R = reproductive

Stages in Colony Life History

Stages in Colony Life History Founder

Queen(s) and brood only.

Ergonomic Workers present Colony growing but rearing only workers

Reproductive Colony is producing queens and males

Orphaned/queenless Queen dead Workers activate ovaries, rear batch of males Colony dwindles and dies

Queenless Stage

Honey Bee: Female Reproductive Systems queen worker

An Apis mellifera queen has massive ovaries with hundreds of ovarioles, and can lay up to 2000 eggs per day. She has a large spherical sperm-storage organ in which she can keep sperm alive for years. The workers have smaller ovaries, a vestigial spermatheca, and cannot mate.

ovaries

spermatheca

Workers lay many eggs in queenless colonies. In the honey bee less than 0.1% of the workers in a colony with a queen have active ovaries, versus up to 50% in queenless colonies.

Apis mellifera Worker-Laid Eggs

The Highly Specialized Colony Life History of

Eciton Army Ants

American Army Ant Eciton burchelli

The soldiers (left) have massive head and jaws with curved back tips. The workers are practically blind.

Eciton Foragers Carrying Prey Item Eciton Raid Patterns

The column raid of Eciton hamatum (left) is adapted to attacking a few well-defended prey like nests of other social insects. The swarm raid of E. burchelli (right) is for flushing out prey in a large area.

Eciton Statary & Nomadic Phases The colony goes between regular statary and nomadic phases. Statary. The brood are mostly eggs and pupae and do not need feeding. The queen’s abdomen is enlarged to lay many eggs. The bivouac stays in the same location for many days and sends out a raiding column each day at a different angle. Nomadic. The brood are in the larval stage and need feeding. The bivouac moves every day to the end of the raiding column, to a new foraging area.

The queen’s abdomen is “physogastric” (swollen).The ovaries are active and she can lay many eggs, many thousand per day.

Eciton Queen During Statary Phase Movement of an Eciton Colony, Panama

statary

statary

nomadic

Eciton hamatum Colony Division Prior to colony division a few young queens are reared. The bivouac of worker ants divide, with about half going with the mother queen and half going with one of the sister queens. The colony is also rearing males. A colony divides only every year or so. Queens are wingless. Males from other colonies enter the bivouac and mate the young queens.

Kin Stucture

Kin Structure A description of a colony in terms of family relationships e.g., workers are offspring of one queen mated to one male.

A description in terms of relatedness e.g. relatedness among workers is 0.75

Note: different kin structures may give the same relatedness multiple mating by a single queen multiple queens in a nest these both reduce relatedness among workers

Main Types of Kin Structure

One queen mated to one male

One queen mated to two males

..to many males

More than one queen