• spp. (Heteroptera : ) • Facultative phytophagous predators ▫ Small predatory bugs (+/- 3mm) ▫ In times of prey scarcity: feeding on plants • Palearctic species • Piercing-sucking mouthparts ▫ Widely used in European greenhouses ▫ Biological control of aphids, whiteflies, thrips, spider mites on eggplants, tomatoes,…

• Two commercially distributed species: • Our objective: ▫ M. pygmaeus and M. caliginosus ▫ Endosymbiotic • Morphologically very similar community in M. caliginosus and M. pygmaeus

Adapted from Vandekerckhove et al., 1999

▫ Symbiosis :’living together of two dissimilar Adapted from Martinez-Cascales et al. , 2006 organisms’ (De Bary, 1879) M. pygmaeus often sold as " M. caliginosus " by ▫ Most important and best known biocontrol companies (Perdikis et al ., 2003, Martinez- endosymbiont: Wolbachia Cascales et al ., 2006, Machtelinckx et al., 2009) Wolbachia

o Obligate intracellular alpha-proteobacterium with an Wolbachia exceptionally wide host range within the o Approximately 66% of all infected (Hilgenboecker et Manipulates the reproduction of its arthropod host  al., 2008) Feminization Infected genetic males convert into females (prevention of the androgenic gland formation) (Rousset et al., 1992) ♂ x ♀

X X X o Possible influence on the fecundity (Vavre et al. , 1999) ♀ ♂ ♂ ♀ ♀ ♂ o In rare cases: obligate for its arthropod host (Dedeine et al ., 2001) ♀ ♀ ♀

Parthenogenesis Male killing

Infected females produce female offspring of • Wolbachia bacteria kill male progeny during embryogenesis unfertilized eggs in haplo-diploids (thelytoky while female progeny survives (Stevens et al. , 2002) via gamete duplication) (Stouthamer et al. , 1990) X ♀ ♂ ♀ X X X ♀ ♀ ♀ ♀ ♀ X ♀ ♂ X♂ ♂ ♂ ♀ ♀ ♂ ♀ Cytoplasmic incompatibility Effect of Wolbachia in M. pygmaeus ?

o Probably most common effect of Wolbachia (Stouthamer et al. , • is infected with 1999) Wolbachia (Machtelinckx et al., 2009) o Cross between an infected male and an uninfected female or a female infected with another Wolbachia -strain results in • An infected strain was cured by adding embryonic mortality tetracycline to an artificial diet based on egg yolk

Source: Engelstädter et al. , 2009

Crossing experiments Crossing experiments

o Infected males with infected females [I- ♂ x I- ♀] o Uninfected males with uninfected females [U- ♂ x U- ♀] o Infected males with uninfected females [I- ♂ x U- ♀] o Uninfected males with infected females [U- ♂ x I- ♀]

Wolbachia causes cytoplasmic incompatibility in M. pygmaeus (only 8 out of 702 eggs hatched) Other endosymbionts? Conclusion • Besides Wolbachia : increasing number of • Wolbachia induces strong CI in M. pygmaeus endosymbionts found in arthropods (Duron ▫ May have vital implications for the commercial et al ., 2008) production of Macrolophus sp. and their use in biological control Rickettsia (MK, P) ▫ Suppression of the population growth by interaction of populations with a different infection status Arsenophonus (“Son-killer”)

Cardinium (CI, P, F)

Spiroplasma (MK)

Future research Thank you • PhD. grant to T. Machtelinckx from ‘Institute for the • Reproductive effect of endosymbionts in M. Promotion of Innovation by Science and Technology in caliginosus Flanders’ (IWT) • Infection status of wild Macrolophus spp. • Organizers of the 12th Workshop of the IOBC AMRQC ▫ Same endosymbiotic community? Working Group and this session ‘The Role of Microbiota ▫ Bidirectional incompatibility? in Mass Rearing and Quality Control’ • Thank you for your attention!