Managing pesticide resistance in Varroa mites, key pests of honey bees

The leading cause of honey bee hive losses in New Zealand is the parasitic mite Varroa destructor and the viral diseases it spreads. Synthetic chemicals, crucial for Varroa control, are becoming increasingly ineffective. This project will investigate miticide resistance and its causes. The PhD student will use physiological and genetic assays to determine pesticide resistance nationwide. They will identify and communicate management strategies to mitigate resistance development. Together, we aim to develop an integrated resistance management strategy, which is a high national priority for our beekeeping industry.

A previous PhD student in my group has found that populations of the parasitic mite have developed resistance to a key synthetic chemical used for mite control [5]. When the mites were first discovered in New Zealand in 2000, they were thought to already have a degree of pesticide resistance, but since this time, this resistance has only increased. Beekeepers and their honey bees in New Zealand need to understand and manage pesticide resistance in order to benefit the bees and enhance the beekeeping industry. Central to an integrated resistance management strategy for Varroa is an understanding of how resistance develops [6].

The aim of this project is to enhance honey bee health and the New Zealand beekeeping industry through the understanding and management of pesticide resistance in Varroa populations. Specifically, our goals are to:

1.    Survey Varroa populations in New Zealand to understand the distribution, prevalence, and extent of pyrethroid resistance. These surveys will be conducted in collaboration with the beekeeping community and use nation-wide sampling from previous work in our group [7].

2.    Define the molecular mechanism for synthetic pesticide resistance in Varroa populations. We have already sequenced gene mutations overseas that are associated with resistance [5]. We have not found evidence of any previously known mutation and suspect that the resistance in New Zealand is from a novel mutation.

3.    Understand the fitness consequences of pesticide resistance in mites. For resistance management, a fitness cost associated with being resistant is typically needed in the pest. Such fitness costs have not always been observed in Varroa [8].

4.    Develop a method that beekeepers can use themselves to monitor resistance. Overseas, the “Pettis test” is a field test that can be used for monitoring pesticide efficacy and for detecting resistant mites on honey bees [9]. We will develop the Pettis test for New Zealand conditions. 

These factors are key components of an integrated resistance management strategy [6], which we will develop using this project. The effective management of these mites is critical for the beekeeping industry [10, 11]. We have an established team with a strong publication track record here at the university, who will be able to supervise the project. This team includes expertise in genetics and genome analysis, beekeeping and the laboratory culture of Varroa populations, ecology, and statistics [5, 7, 12, 13]. We have links to the beekeeping industry throughout New Zealand that will facilitate the success of this research project.

The ideal student for this role will have an interest in entomology and experience with honey bees. The person will have a knowledge of molecular genetics and laboratory skills with PCR, bioinformatics and statistics. You should not be allergic to honey bee stings. Your application should include a covering letter, a CV with degrees and information on grades, and the names of three referees. Please note that Victoria University of Wellington PhD programme entry requirements, and other information, is available a https://www.wgtn.ac.nz/fgr/apply