Wildlife Aliens and Diseases

Available for over a year

Does the increase in human population mean more diseases for domestic and wild animals and plants? As trade between different countries and continents increases we move more animals and plants around the world. With them go diseases that can be devastating for local wildlife. Ash die-back and the Varroa mite on bees are two recent examples that are causing real concern. Monty Don explores how our need for worldwide trade is carrying pests and diseases to places where there is no resistance. The Varroa mite is an Asian species that has lived on the Asian variety of honey bee (Apis cerana) without causing too much damage to a colony. Where it has evolved it breeds only on male bees and, as they are not as numerous as females in a colony, it has little effect on the hive. Man moved colonies of the European honey bee (Apis mellifera) to Asia, and at some point in the last century the mite 'jumped species' onto the European honey bee. In European hives the mites can breed in the cells of worker bees. This alters the population dynamics of the mites and they multiply out of control so that - without human intervention - the colony will die. Varroa has now spread across the globe, reaching the UK in 1992. There are now very few wild colonies of honey bees left in the UK - they have been largely wiped out by the introduced Varroa mite and the viruses it transmits. What can be done? Do we have a plan to stop this happening again and can we forsee what the next crisis will be?