Defensive alkaloid in blood of Mexican bean beetle (Epilachna varivestis)

Summary The blood of the Mexican bean beetle (Epilachna varivestis) contains a homotropane alkaloid, euphococcinine (1). The beetles reflex bleed when disturbed, thereby deploying the alkaloid, which is provenly deterrent to spiders and ants. Newly emerged adults lack the alkaloid, but the compound builds up to deterrent levels in their blood within days. Eggs and larvae ofEpilachna are devoid of the compound.Paper No 79 of the series: Defense Mechanisms of Arthropods. Study supported by NIH (Grants AI-02908 and AI-12020) and Hatch Funds (NYC-191409). We thank G. Eidens, K. Hicks, and M. Eisner for excellent technical help, and an anonymous reviewer for calling two critical references to our attention. The ant tests were done at the Archbold Biological Station, Lake Placid, Florida. The hospitality of the Fogarty Scholar-in-Residence Program (to J.M.) is acknowledged with pleasure.