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Improving lucerne pollination with leafcutter bees – stage 2 By Dr Denis Anderson
August 2006
RIRDC Publication No 06/108 RIRDC Project No CSE-91A
During Stage 1 of the current
project (1999-2002), the complex quarantine and environmental issues involved
with importing the leafcutter bee from Canada and getting it established
in the field were resolved. The current Stage 2 project was aimed at improving
the import procedure to deal with large importations of the bee. The project
objectives were:
When developing the present
Stage 2 project it was anticipated that the research would be jointly funded
as in Stage 1, by RIRDC and GRDC, with in-kind assistance from seed companies
and independent growers. However, shortly before the project commenced,
GRDC withdrew support for the leafcutter bee initiative. The subsequent
reduction in funding led to a tightening of the scope of the project. Hence,
no bees that emerged in quarantine could be managed by the project, as
was the case in Stage 1. Instead, industry partners purchased the bees
and managed them in the field once they were released from quarantine.
This allowed project work to focus on streamlining the quarantine procedure
for dealing with large numbers of bees, checking for pests and diseases,
and making simple observations on released bees in the field.
Importations of large numbers of Canadian leafcutter bees were made during each of the 2002/03, 2003/04 and 2004/05 Australian lucerne growing seasons.
In December 2002 approximately one million leafcutter bee cells were imported from the Peace River District of Alberta, Canada on behalf of Pioneer Hi-bred Australia and two independent lucerne seed producers based at Keith in South Australia. Upon arrival in Australia the bees were introduced into the high security quarantine centre at CSIRO Entomology in Canberra and handled using the equipment and methodologies developed in Stage 1. However, improvements were made to the way that new bees emerged in quarantine, which more than halved the quarantine processing-time. A total of 711,802 adult leafcutter bees emerged from the imported cells giving an emergence rate of 71%. Of these, 533,752 were released on to a large lucerne seed crop near Cowra, NSW, 89,025 on to a single lucerne seed crop near Keith, South Australia, 44,512 on to a second lucerne seed crop near Keith, and 44,513 on to a mixed lucerne/clover field near Bordertown, South Australia. A further 200,000 leafcutter bee cells, that were recovered from bees that has been released at the same locality during the 2001/02 season as part of RIRDC project CSE-86A were also placed into shelters at the Cowra site. The recovery of cells from bee released at the Cowra site was below expectations, but cells recovered from the Keith and Bordertown sites almost equalled the numbers of bees released.
In December 2003 approximately 1.2 million leafcutter bee cells were imported from the Peace River district on behalf of Pioneer Hi-Bred Australia. These were again processed through quarantine, where 800,000 adult bees emerged, giving an emergence rate of 67%. All these bees were released on to a large lucerne crop near Cowra, together with 300,000 cells carried over from the previous year.
The released bees, and those that emerged from the previous year’s cells, showed excellent flight and forage activity. However, most were subsequently killed by an insecticide treatment of the crop.
In January 2005, approximately 1.2 million leafcutter bee cells were imported on behalf of Seedmark.
A total of 701,124 adult bees emerged from the quarantined cells, giving an emergence rate of 58.4%.
This was the lowest emergence rate recorded for imports handled during Stages 1 and 2 of this project, and resulted from a higher than normal level of parasitoid infestation of the imported cells. Only 70,000 cells were recovered from the released bees. This disappointing return was due to the very cool weather conditions that persisted from the later than normal release date until the removal of nesting blocks from the field, which prevented most of the bees from foraging and producing offspring.
In other project work, a DNA fingerprinting method was developed for distinguishing between imported and indigenous leafcutter bees.
The three large successful
importations of leafcutter bees made during this project showed that the
quarantine procedures were safe and robust enough to deal with very large
importations. Such importations will be needed in the future if a leafcutter
bee industry is to become established in Australia. It is now up to the
lucerne seed industry to exploit the opportunity provided by this project
(and the previous Stage 1 project), and move towards establishing the bee.
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