Summary1. Ants provide variable protection against herbivores to ant-plants (i.e. myrmecophytes and myrmecophiles). The ways in which ant-plants dynamically adjust both their direct (chemical and physical) and indirect (biotic) defences in response to varying levels of herbivory are not well understood. 2. We experimentally generated a broad range of ant-attendance levels and herbivory pressures in a tropical myrmecophyte, Cordia nodosa, which allowed exploration of the inducibility of and interactions between direct and indirect resistance traits. 3. In response to increased herbivory, host plants encouraged indirect (biotic) defence by increasing domatium volume, regardless of whether ants were present on the plant. When ants were present, larger domatia housed more workers, which in turn decreased herbivory on adjacent leaves. 4. Independent of the presence of ants, plants responded to increased herbivory by inducing both chemical (phenolics) and structural (leaf toughness, trichomes) resistance traits; these traits were associated with reduced palatability to a folivorous beetle. 5. Synthesis. Our results show that both direct and indirect defences are inducible in C. nodosa, which suggests that C. nodosa may retain direct defences as insurance against varying levels of protection from its ant bodyguards. Thus, the predictions of optimal defence theory are not violated: although C. nodosa invests in multiple forms of defence, they are not redundant.

Graphical abstract

This is the first report of a disseminated mycobacteriosis caused by Mycobacterium kansasii in a reindeer (Rangifer tarandus). A two-year-old female reindeer with a history of lethargy and dyspnea was diagnosed with multiple pulmonary abscesses radiographically. At necropsy the animal had severe diffuse granulomatous pneumonia and pleuritis with severe multifocal granulomatous m yocarditis, lymphadenitis, nephritis, esophagitis, enteritis, and thyroiditis. Impression smears of necrotic debris from granulomas contained numerous acid-fast bacilli. M. kansasii was cultured from pulmonary, renal, hepatic, and lymph node sections. M. kansasii is a slow-growing photochromogenic non-tuberculous mycobacterial species that causes disease in severely immunocompromised individuals (3,4,9). Due to the popularity of reindeer as animals for exhibition in children's zoos, petting zoos, and holiday exhibitions, diagnosis of Mycobacterium kansasii in a reindeer is a significant public health concern.