It’s not what you know, but who you know!

Whilst humankind often debates the benefits – or otherwise – of an individual’s advancement based on patronage rather than merit, it is interesting to note that the plant world has no such scruples. Well, at least that seems to the message when it comes to botanical self-preservation in members of the Adoxaceae, according to work by Gaylord Desurmont and colleagues (PNAS 108: 7070–7074, 2011). The team tested the idea that ‘invasive pests may be facilitated by the evolutionary naïveté of their new hosts’ by exploring the love–hate relationship between Viburnum spp. and viburnum leaf beetle (Pyrrhalta viburni), which is wreaking havoc amongst North American native wayfaring trees and guilder roses. In field experiments involving the beetle and 16 Viburnum spp. they discovered that Old World spp. – that had evolved in the presence of the beetle – defended themselves vigorously against attack: ‘naïve’ North American taxa (those without evolutionary exposure to Pyrrhalta) showed a much lower response. The workers conclude that colonisation of undefended resources may be as much a feature of success of invasive insects as potential absence of predators in their new environment. Which goes to show that exposure to harmful agents can help to toughen you up. Or, in other words, what doesn’t kill you makes you stronger – eventually, over evolutionary time. And for those who are curious, the Viburnum defence reaction involves a massive wound response with production of tissue that crushes the beetle’s eggs. Always nice when plants get their own back on those pesky animals!