Apicultural practice and disease prevalence in <i>Apis mellifera</i>, New Zealand: a longitudinal study

Abstract

In New Zealand, the introduced honey bee (Apis mellifera) is a valuable production animal, providing pollination services for horticultural crops and significant export volumes of honey, especially mānuka honey. Honey bees in New Zealand are free from a number of significant diseases and pests such as European foulbrood, acarine disease, small hive beetle, Israeli acute paralysis virus and tropilaelaps mites. We sought to determine the health status of honey bees in New Zealand using a longitudinal study that followed 60 beekeepers over 2.5 years, ascertaining disease and pest status in their elected study apiary and interviewing them every spring and autumn. Participant beekeepers accounted for the management of approximately 12% of the beehives registered in New Zealand. Differences in beekeeping practices were observed between the North Island and the South Island. Nosema ceranae was found almost exclusively on the North Island and did not displace Nosema apis over the course of the study. Lotmaria passim showed a reverse-phase seasonality to nosema, peaking in autumn at near 100% prevalence. The prevalence of Varroa in apiaries varied seasonally between 45.0% and 46.7% in spring and between 65.0% and 69.5% in autumn, with most infestation rates below 3 mites per 100 bees. The detection rate of symptomatic American foulbrood disease during our hive inspections was very low, between 0.00% and 0.85% hive-level prevalence dependent on the season. This study sets a foundation for understanding honey bee health in New Zealand.