Lethal doses of oxbile, peptones and thiosulfate-citrate-bile-sucrose agar (TCBS) for Acanthaster planci; exploring alternative population control options

•We examine protein extracts as novel methods to control Acanthaster planci.•Oxbile and ox gall are promising A. planci control options.•Novel control method could increase efficiency of control efforts.•No disease transmission was observed in corals, echinoderms and fishes that were in contact with sick COTS.

Effective control of outbreaks of Acanthaster planci represents the most immediate and practical intervention to reverse sustained declines in coral cover on reefs in the Indo-Pacific. This study explored the minimum doses of oxbile, oxgall, and thiosulfate-citrate-bile-sucrose agar (TCBS) that result in reliable and comprehensive mortality when injected into adult A. planci. The minimum doses required to induce 100% mortality among starfish (n = 10) were 4 g l−1 of oxbile, 8 g l−1 of oxgall and 22 g l−1 of TCBS. Moreover, there was no evidence of unintended side effects for other coral reef organisms (e.g., scleractinian corals, echinoderms and fishes) when using oxbile, oxgall, or TCBS at minimum doses. The effectiveness of peptones in killing crown-of-thorns starfish was also tested, but inconsistency in the results revealed that these proteins are unreliable.