Genetic variation of Varroa jacobsoni and pathology of microbial pathogens
Project code: PRJ-003338
Project stage: Closed
Project start date: Friday, January 15, 2010
Project completion date: Friday, November 22, 2013
National Priority: HBE-Improve understanding of nutrition best practice and disease interaction
In June 2008 Varroa was found destroying hives in the Papua and New Guinea. It was initial thought to be V. destructor, but subsequent DNA analysis revealed it to be a previously unknown form of Varroa jacobsoni which has evolved the capacity to shift onto Apis mellifera worker brood and reproduce. Previously this mite had been associated primarily with Apis cerana. The mite has since been discovered to be widespread throughout the Eastern Highlands, Chimbu, Western Highlands and Enga provinces and has also been detected in Lae and near Port Moresby. This discovery now means that the main risk of Varroa entering Australia has shifted from via Apis mellifera, to via Apis cerana (given that we get many more arrivals and incursions of Apis cerana, than Apis mellifera). The mite is killing Apis mellifera colonies in PNG and we can only assume that it is equally as dangerous as the K and J types of Varroa destructor. Critical information is now needed to delimit the threat to Australia. We need to understand the genetic composition of this mite as this gave critical clues that enabled us to understand how this mite evolved and whether we are dealing with a single clone or multiple clones; this will point to the origin and direction of spread. We will also determine what microbial pathogens (particularly viruses) are transmitted by the new mite, determine whether these are similar to those in V. destructor; this will give clues to the potential impact.
The objectives are:
(a) Develop nuclear DNA markers such as microsatellite DNA and exon-primed intron-crossing (EPIC) markers capable of detecting genetic variation within the species of Varroa jacobsoni.
(b) Determine the level of genetic variation among varroa mites on Apis cerana in Java and among varroa mites on both Apis cerana and Apis mellifera in PNG (note that the varroa mites in PNG are descendants of varroa mites on Apis cerana in Java, hence most variation should be found among the mites infesting Apis cerana Java, then signs of a ‘bottle-neck’ should show in mites on Apis cerana in PNG and a clone should show up on Apis mellifera in PNG that is, if all the mites on Apis mellifera arose from a single female).
(c) Determine what microbial pathogens (particularly viruses) are transmitted by the new varroa mite in PNG.