Data from: Invasion dynamics of Wolbachia bacteria in laboratory populations of the wasp, Trichomalopsis sarcophagae (Hymenoptera: Pteromalidae)

Wolbachia are obligate intracellular bacteria common in diverse arthropod
hosts.  Infections are spread from infected mothers to their
progeny via egg cytoplasm.  Establishment and spread of
infections are affected by the number of infected individuals invading the
novel host population plus the effect of infections on the production of
female progeny and mating behaviour.  Taking these factors into
account, we examined the ability of Wolbachia to establish and spread in
populations of the parasitoid wasp Trichomalopsis sarcophagae (Gahan)
(Hymenoptera: Pteromalidae), a species for which the effect of Wolbachia
infection on host reproduction has not been previously examined. 
Experimental crosses showed that infections caused 100 percent cytoplasmic
incompatibility (CI), wherein uninfected females mated with infected males
(♀ x ♂w) only produced male progeny and broods of smaller size. 
All other mate combinations (♀ x ♂, ♀w x ♂w, ♀w x ♂) produced normal
broods of similar size and sex ratio.  The expression of this CI,
however, has two forms.  Fertilized eggs from the incompatible
cross either develop as though male, or fail to develop.
 Mate-choice tests showed that females mated once and showed no
preference for infected or uninfected males.  An experiment
tracking the extinction or subsequent establishment and spread of
Wolbachia infections in laboratory colonies for 20+ generations indicated
an establishment threshold for infection prevalence of less than 10%.
 The existence of such a threshold, and its relatively low value,
is broadly consistent with a simple mathematical model informed by the
results from the experimental crosses and mate-choice tests. This is one
of few experimental studies tracking the spread of Wolbachia infection in
an insect species.  It helps explain why Wolbachia is such a
successful and widespread parasite.