An Epizootic of Rickettsiella Infection Emerges from an Invasive Scarab Pest Outbreak Following Land Use Change in New Zealand
Rickettsiella spp. are tiny obligate intracellular bacteria frequently pathogenic to a range of arthropods. As a consequence of being difficult to diagnose, little is known about their biology and ecology, and the importance of Rickettsiella diseases in insect population regulation has been under estimated. Land use change to increase agricultural productivity has produced unintended consequences by generating wide scale pest outbreaks that threaten economic viability of the development initiatives. On the West Coast of the South Island in New Zealand, land improvement through ‘flipping’ and ‘hump & hollow’ earth movement has created productive pasture land, but produced a widespread outbreak of manuka beetles (Pyronota spp.) reaching unprecedented densities and causing severe damage to pasture. Over time a reduction of manuka beetle densities back to ‘normal’ levels was observed, and it was determined to be the result of an epizootic of bacterial disease caused by the Rickettsiellapopilliae pathotype ‘Rickettsiella pyronotae’, which spread through the outbreak pest group.