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NEW ZEALAND BEEKEEPER, DECEMBER 2016
NOSEMA BREAKTHROUGH REPORTED PEST AND DISEASE CONTROL
Additional parasitoid introductions Yes, not enough wasps are being killed. This is why we went on to introduce two more parasitoids, the North American S. v. burra and the Middle Eastern S. orientalis. These two enemies of other social wasps did not have the genotypes of either of our two species of wasps as victims, and the thinking behind their introduction was that we wanted our wasps to be confronted by enemies that did not ‘speak’ to them, to use the terminology of Groenteman (2016). What we were looking for was an enemy that to wasps would be as lethal to them as varroa is to honey bees. Varroa originated from the Eastern honey bee and so does not ‘speak’to our Western honey bee, which consequently is unable to understand that it is being attacked. Whether the new parasitoids are established or not is unknown because the cancellation of funding by the Foundation for Research, Science and Technology in 2005 meant that all work in this area ceased. But we had plans to introduce even more enemies specific to wasps, such as more strains of Sphecophaga from Asia and especially Korea and Formosa, four species of a beetle parasitoid in the genus Metoecus, and up to five species of parasitic wasps in the genus Bareogonalis (Donovan, 1996). All these enemies attack wasp brood, and we hoped that the more enemies we could establish here, the more they would interact synergistically in a wasp nest to foster a greater level of attack by each of them. The successful establishment and expansion of S. v. vesparum over the past 28 years shows that the importation of wasp enemies is a viable strategy. With luck, Landcare researchers will be able to expand their wasp biocontrol project to increase the number and range of enemies to the point where wasp numbers are permanently reduced. References Barlow, S. D., Beggs, J. R., & Moller, H. (1998). Spread of the wasp parasitoid Sphecophaga vesparum following its release in New Zealand. New Zealand Journal of Ecology, 2 2(2): 205–208. Donovan, B. J. (1996, June). Progress with biological control of wasps. The New Zealand Beekeeper, 3 (5): 12–13. Groenteman, R. (2016, October). Wasp biocontrol updates: Sphecophaga again. The New Zealand Beekeeper, 2 4(9), 950–951.
The New Zealand Institute for Plant & Food Research Limited
Our small but mighty bees are under siege from a range of pests and diseases. Thankfully, some relief may be in sight for these important insects from a particularly dangerous disease—one that can destroy entire hives.
Assessing brood viability after heating comb to kill Nosema. Copyright © Plant & Food Research. All rights reserved.
Preliminary results from a pilot study undertaken by scientists at Plant & Food Research indicate that a breakthrough has been made in the fight against the pathogen Nosema ceranae. N. ceranae is a cousin of N. apis , which has been endemic in New Zealand since the 1800s. Both are spore-producing parasites that attack the gut lining of bees, leading to a shortened lifespan in adults. In severe cases, the entire colony can collapse. Because Nosema is primarily spread through faeces on contaminated honeycomb, preventing any infection is a near-impossible task for the beekeeper, meaning that bee health and commercial costs of Nosema have largely been seen as ‘a fact of life’. During the springs of 2014 and 2015 many New Zealand beekeepers, particularly in the Coromandel, experienced severe and unexplained colony losses—a pattern that had not been seen before. Affected colonies initially appeared strong and healthy coming out of winter. However, over a short period virtually the entire colony would disappear, leaving behind a healthy queen with brood and a few hundred worker bees. Productivity loss was estimated at between 40–60% for
the season. Nosema ceranae had first been identified in New Zealand in 2010 and was fingered as a potential culprit for the losses after the development of a diagnostic test by John Mackay from dnature Ltd. In response, a team from Plant & Food Research began a collaboration with Coromandel beekeeper Dr Oksana Borowik—initially confirming high levels of N. ceranae in affected colonies, and then exploring potential management initiatives to prevent the spread of the disease between hives. Their early findings are exciting: heat-treating the comb and hiveware to 50°C for 90 minutes killed Nosema ceranae spores, increased brood viability and ultimately increased bee numbers by 50%. The team will attempt to replicate these results and build on this initial study with further investigations into the effect of seasonality and long-term heat treatment on bee populations. If heat treatment is found to be a safe and consistent management option for beekeepers plagued by Nosema , this research has the potential to greatly improve the health and productivity of New Zealand beehives—and the lives of those tending them—well into the future.
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