Arthropods exhibit a large variety of sex-determination systems both at the chromosomal andmolecular level. Male heterogamety, female heterogamety, and haplodiploidy occurfrequently, but partially different genes are involved. Endosymbionts, such as Wolbachia,Cardinium, Rickettsia and Spiroplasma, can manipulate host reproduction and sexdetermination. Four major reproductive manipulation types are distinguished: cytoplasmicincompatibility, thelytokous parthenogenesis, male killing and feminization. In this review, wesummarize the effects of these manipulation types, and how they interfere with arthropod sexdetermination in terms of host developmental timing, alteration of sex determination andmodification of sexual differentiation pathways. Transitions between different manipulationtypes occur frequently, which suggests that they are based on similar molecular processes. Wediscuss how mechanisms of reproductive manipulation and host sex determination can beinformative on each other, with a special focus on haplodiploidy. We end with futuredirections on how study of endosymbiont manipulation of host reproduction can be key tofurther study of arthropod sex determination.