Friday, June 05, 2009

Varroa mite not such a threat to Papua New Guinea coffee

A collaborative research between Australian and Papua New Guinea scientists has revealed that the potential economic impact of a new Varroa mite (pictured above feedling on a honeybee) on Papua New Guinea agriculture is likely to be much less significant than speculated earlier.
 This outcome was discussed at a research review workshop hosted by the National Agricultural Research Institute (NARI) in Lae last month which gathered a number of key agencies working together on the issue.
 The new variant of the varroa mite (Varroa jacobsoni) was first found in PNG on European honeybees (Apis melifera) in the Eastern Highlands in May 2008.
 The mite is now thought to have been in PNG for about six years. 
There were concerns the mite, which can decimate colonies of European honeybees, could significantly reduce the yields of a number of pollinated crops. Earlier predictions were that coffee yields alone could be cut by as much as 50%.
However, the study, just completed by scientists from NARI and the Australian-based Commonwealth Scientific and Industrial Research Organisation (CSIRO), predicts that in a worst-case scenario, the mite would lead to annual economic losses to the coffee industry of less than K14 million, a fraction of the earlier prediction of K200 million.
The results of the CSIRO/NARI study, funded by the Australian Centre for International Agricultural Research (ACIAR) and Australia’s Rural Industries Research and Development Corporation (RIRDC), were discussed by a number of agencies at the workshop in Lae, including representatives of NARI, CSIRO, ACIAR, the National Agricultural Quarantine and Inspection Authority, the Coffee Industry Corporation and Eastern Highlands provincial offices of the Department of Agriculture and Livestock.
“The study surveyed food and cash crops dependant on insect pollination and assessed their degree of dependence on insect pollination,” said CSIRO ecologist Dr Saul Cunningham. 
“It also surveyed pollinator insects that visit selected dependent crops both in the highlands and lowlands of the country.
“In PNG, the distribution of managed European honeybees (Apis mellifera) is restricted to the cooler highlands of PNG, whereas the feral Apis cerana are found throughout the country.
“Based on established knowledge from elsewhere, it is expected that Apis mellifera provide significant pollination services to highland crops like coffee, cucumber and orchard tree crops.  While pollinator dependent lowland crops like coconuts, oil palm and some vegetables are serviced by Apis cerana and other pollinator insects that do not appear to have been affected by the new strain of Varroa mite.”
In view of its relatively-high contribution to annual cash incomes of smallholder farmers in the densely-populated highlands of PNG, and its significance to the national economy, the scoping study focused on the likely economic impact that mite may have on the PNG highland (Arabica) coffee.
 The study developed an economic simulation model to estimate probable economic losses from coffee production over a period of years.
“The study showed that the earlier estimate of K200 million worth of annual drop in coffee production due to decline in pollination services is therefore considered a very unrealistic scenario in PNG,” Dr Cunningham said. 
“We predict that given the likelihood that other insects, such as the feral bee species Apis cerana and native bees, will continue to pollinate coffee, the impact could be even smaller than K14 million. 
“The workshop concluded that further targeted research would more accurately predict whether the impacts are closer to K14 million or K4 million annually.
“Further research is also needed on coffee pollination in PNG style coffee gardens, on which insects are involved, and how much they boost yield.  Such research would not only help understand the risks posed by Varroa mite, but would also help improve coffee production practices in the future.”
  Preliminary findings from a separate survey of Varroa mites in all PNG provinces indicate that the Varroa mite is widespread in the country, suggesting the need to initiate appropriate and sustainable parasite management interventions such as targeted application of chemicals, restriction of movements of bee colonies and hive equipment and other quarantine measures.
The coffee industry is already experiencing a gradual decline in supplies of coffee to the market, although the causes for this decline are still unknown. Further research work is needed to identify the possible causes and assess their relative importance.
Further information about results of this study can be obtained from Dr. Saul Cunningham of CSIRO in Canberra (Email: )  or Dr Workneh Ayalew of NARI in Lae (Email: ).
The final report from the scoping study will be available from ACIAR later in 2009.

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