Thelytoky occurs in several species of insects, but it is considered
to be the exception to the rule. Schilder makes the case that it is
an example of an evolutionary trend *back* to a more primitive form
of insect:

 From 'Safer Without Sex" by Klaus Schilder:

"Good examples of the initial step in reverse social evolution,
facultive thelytoky in the absence of the queen, include the Cape
honeybee. Unlike workers in other honey bee races, here workers
possess several queen-like pre-adaptations that may have facilitated
the evolution of thelytoky: Workers have an increased reproductive
rate compared to the closely related A. m. scutellata, due to a
higher number of ovarioles.

Functional monogyny [one queen] is a reproductive strategy very
sensitive to the loss of the sole reproductive. Thelytokous
parthenogenesis is a possible adaptation to the threat of orphanage
allowing worker groups to sustain a colony and possibly rear
replacement queens. In capensis, risk of queen loss during mating
flights may be particularly high due to strong and changing winds in
the Cape region. Upon queen loss, orphaned colonies may requeen from
the brood of the previous queen, an egg-laying worker, or remain a
laying worker colony."


[PB: it is important to add that no study (that I know of) has been
done on the viability of queens reared by laying workers. It is
plausible that most of these queens would be rapidly superseded by a
normally raised queen, minimizing their contribution to the make-up
of the colony, or the overall gene pool. It is known that colonies
headed by laying workers tend to dwindle, even in the Cape Bee.]

--
Peter Borst <[log in to unmask]>