Social Insect and  Social Evolution Research  at Sheffield University

The Behavioural Ecology Research Group in Sheffield:
 

Worker policing in honey bees and wasps

In many species of social Hymenoptera workers cannot mate but possess ovaries. Because of
haplodiploidy any unfertilized eggs they lay are male. In some species of social Hymenoptera, such
as bumble bees and Dolichovespula wasps, many of the colony's males are workers' sons. In other
species, such as the honey bee and Vespula wasps, very few of the colony's males are workers'
sons. My experimental research has shown that in the honey bee workers prevent each other from
reproducing-known as "worker policing". Worker bees eat eggs laid by other workers but leave
eggs laid by the queen. Recognition of eggs is mediated by a queen-produced egg-marking
pheromone. Inclusive fitness studies have shown that worker policing is favored by natural selection
when queens are inseminated by more than two males, as in the honey bee and Vespula wasps.
Current projects are investigating the origin and chemical nature of the honey bee egg-marking
pheromone; costs and benefits of worker policing in the honey bee; queen mating frequency and
male production by workers in wasps; worker policing and reproduction in vespine wasps (Vespa,
Provespa, Dolichovespula, Vespula).

Modeling animal social behavior

Many animals spend part or all of their life in a social group. For example a bird family, a colony of
honey bees or other social insects, the brood of a parasitic wasp developing within a single host. A
variety of techniques, such as game theory and inclusive fitness modeling, can be used to build simple
mathematical models of social behavior. My particular interest is studies of reproductive behavior,
conflict and cooperation. Current projects are investigating worker policing in honey bees, facultative
sex allocation by workers in ant societies, the evolution of mating systems, conflicts among parasitic
wasp larvae, parental and helping behavior in birds, kin recognition.

Diseases

Honey bees are hosts to a variety of mites and microorganisms, many of which cause diseases. One
such disease is known, despite occurring in Britain, as American foulbrood (AFB). AFB is caused
by the bacterium Bacillus larvae. It is a serious disease of larval honey bees and kills colonies.
Larvae killed by AFB remain in their cell and provide a source of infective spores to spread the
disease within the colony or to nearby colonies-AFB spores are long lived and dead colonies are
attractive to workers from other colonies who come to salvage any remaining honey. Current
projects are investigating the epidemiology of AFB within and between colonies; the effect of the
wax moth, whose larvae eat and destroy wax combs in dead and dying colonies, on between colony
spread of AFB; AFB control methods.

Vespine wasps are a major group of social insects apparently without micro-organism-caused
diseases. Are they really disease free or does the absence of diseases merely reflect a lack of data?
Wasp nests are currently being collected to examine for disease symptoms. Studies of live nests will
attempt to uncover diseases by obtaining samples of individuals behaving abnormally, dead or dying
individuals, and brood or adults being removed from the nest by workers carrying out hygienic
behaviour. The study of wasp diseases will fill an important gap in what is known about their ecology
and may have implications for biocontrol of Vespula wasps in New Zealand, where they are an
introduced pest.

Sheffield has a field laboratory (in experimental gardens 1.5 km from main building) for studying live
bee and wasp nests, with equipment for 50 honey bee hives, observation bee hives, queen mating
hives, instrumental insemination equipment, observation nests of Vespula and Dolichovespula
wasps, woodwork shop for making bee hives and wasp nests, and honey extraction equipment. The
social insect group has the exclusive use of an ultracold freezer for storage of frozen wasp nests and
other samples. A DNA lab for microsatellite studies to determine kinship is being established.

Sheffield can provide training in theory and modeling of social insect behaviour and evolution (e.g.,
inclusive fitness, game theory and genetic models of reproduction and conflict; simulation models of
foraging and organization), and has co-organized a training workshop in kinship theory with Aarhus
in June 1997 at Mols, Denmark. The Sheffield group will organize another network workshop on
"Social Insects as Model Organisms" in July 1999. Sheffield also provides a location for the
experimental study of honey bees and vespine wasps (c. 7 local species with Vespula vulgaris and
Dolichovespula sylvestris being the most abundant) as model systems in studies of kinship &
relatedness, reproduction & conflict, recognition, mating behaviour, diseases, productivity etc.
Network postdocs or other lab members wishing to work on honey bees or wasps can visit
Sheffield to broaden the taxonomic scope of their expertise and to pursue a research question within
a different taxonomic group.(If you are tired of ants come to Sheffield!)

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last updated: 29/08/98