Thelytoky is a type of parthenogenesis reproduction where unfertilized
eggs develop into females (Suomalainen 1950).
Apis mellifera Capensis, the Cape bee, parasitises on a regular basis
A.m. Scutellata, better known to us as the Killer Bees, in certain parts
of South Africa. The Capensis workers are so genetically identical
to A.m. Scutellata, that the former are refered to as a 'pseudo-clone'.
Over a period of time this parasitism results in colony death of Scutellata.
Capensis does not forage in these colonies and that is where the pinch
comes. The Capensis workers lay diploid (female) eggs via thelytoky.
When thelytokous worker reproduction occurs, worker policing has
little or no effect, and that in a queen-right colony. But worker policing
is aimed at haploid eggs, which would normally be the case with
laying workers. Possibly the failure to police these worker laid eggs
lies with the pheromone (the scent) of the diploid egg. The Capensis
worker can evidently mimic the queen's pheromone as well, or has
its own pheromone, which overrides the queen's.
A study of this thelytoky phenomenon was conducted roughly 15 years
ago in the USA. What is common in the Cape bee occurs with con-
siderally lower frequency in European honey bees. In rare instances,
virgin queens and laying workers produce diploid eggs, that develop
into females. In this study 18 colonies were used. One queen pro-
duced from laying workers eggs successfully mated and produced
worker and drone brood. As stated, the bees were from commercial
European stock, indicating that thelytoky may exist as part of the
overall Apis mellifera gene pool, and Apis mellifera is a pretty large
grouping - around 20+ subspecies. However, reports indicate that
in managed colonies thelytoky is expressed at a very low frequency
(Mackensen 1943). This may be because beekeeping practices
inadvertently select against thelytoky. For example, if colonies lose
their queen and suitable brood is not there, the beekeeper acts
rapidly to remedy this situation. Hence, there is no selective
pressure for development of thelytoky in colonies of managed bees.
-----------------------------