Varroa Increasingly Responsible For NZ Bee Colony Losses

New Zealand beekeepers have reported varroa to be the most common reason for over-wintering hive losses for the first time, according to the recently released NZ Colony Loss Survey.

The 2021 Survey found varroa was responsible for nearly 40% of all losses. This marks a change in the primary cause, with queen problems having consistently been attributed as the key reason for colony losses in the past six years of the survey.

The Survey noted that an estimated 5.3% of all living colonies were lost to varroa and related complications over the 2021 winter, significantly higher than the 1.6% recorded just five years ago.

Beekeepers surveyed reported a number of reasons for the losses due to varroa; including reinvasion post treatment and timing issues with treatments. Nineteen percent believed their varroa losses were due to ineffective products.

The report makes for sobering reading says Barry Foster, chair of Apiculture New Zealand’s Science and Research Focus Group.

“While there are multitude of factors attributed to varroa losses it is worrying that approximately 4% of beekeepers surveyed did not treat for varroa at all during the 2020/2021 season and that about a quarter of beekeepers surveyed do not monitor the success of their treatments, says Barry.

“Treating is only the first part of varroa management; you have to monitor to make sure those treatments have worked—otherwise you are leaving your hives, and the hives of others, at real risk.”

Overall, the winter loss rate was 13.6%, which equates to 109,800 colonies lost with regional variation an ongoing trend. The region with the greatest overall loss rate, and the highest loss rate attributed to varroa was the mid-North Island region—encompassing the Waikato, Bay of Plenty, Gisborne and Hawke’s Bay. The region reported 18.7% winter loss rates, with 8.6% of all colonies in this region lost to varroa.

“The fact that our colony losses are increasing year on year is a worrying trend and we need to up the ante in how we address the issues. That requires a united commitment to investment in research and education and a good start would be a commodity levy, something currently missing in the bee sector,” says Barry.

For the second year, NZ Colony Loss Survey asked for beekeepers’ sentiment on range of factors. Respondents were less positive about the economics of beekeeping, environmental factors, and the beekeeping lifestyle than in 2020. The report notes that “Given challenges presented by COVID-19, and low prices for non-mānuka honey, coupled with a sharp increase in reported varroa and wasps, a more pessimistic outlook is perhaps not surprising.”

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