are then consumed by D. chrysippus larvae. S. flavohalterata does not kill the larvae, and development is normal until the pupal stage, when larvae dies and the parasite emerges from the pupa instead. A. chrysippi, a parasitic wasp of the family Braconidae, oviposits on larvae early in their development and then kills them in the later stages. As many as fifty wasps may emerge from one large caterpillar, and they then pupate on the deceased host. Parasitic wasps of the genus Charops also infest plain tiger populations, likely during the egg or first instar stage, and then kill the larvae in a later instar stage. Sturmia convergens is also a parasitoid of D. chrysippus. Diseases The plain tiger is infected by a male-killing bacterium called Spiroplasma. Male-killing bacteria are transmitted vertically, from mother to offspring. Female plain tigers infected with Spiroplasma will produce all-female broods, because the bacteria kills infected male offspring during either their embryonic or first larval instar stage. Although male-killing bacteria are uncommon in species which lay eggs singly, experimentally treating infected females with antibiotics restored an even sex ratio to their subsequent broods, thus indicating that it is indeed Spiroplasma which is responsible for all-female broods in D. chrysippus. However, the prevalence of this bacteria in the plain tiger seems to be restricted to east African populations. Protective coloration and behavior The plain tiger is mimicked by several species due to its unpalatability to potential predators. Previously, it was thought that cardenolides obtained from food sources during the larval stage were responsible for the aversive nature of adult D. chrysippus, but many larval food sources lack cardenolides, and some adult West African populations of D. chrysippus do not store cardenolides well, yet still repel predators. More recently, pyrrolizidine alkaloids have been proposed to be also responsible for the unpalatability of D. chrysippus. Adult male danaines often feed on plants containing pyrrolizidine alkaloids, and although females rarely do, they may be protected simply through their resemblance to males of the same species. The ability of D. chrysippus to store cardenolides varies across populations, so likely both cardenolides and pyrrolizidine alkaloids contribute to the unpalatability of D. chrysippus to different extents depending on the population. Because the plain tiger is unpalatable (also called inedible), they are aposematic - their bright coloration serves as a warning to predators that they are either distasteful or toxic. Consequently, once a predator