Research shows bees not the main vectors of cucumber green mottle mosaic virus

By Ashley Walmsley

BEES themselves may not be the culprits for spreading cucumber green mottle mosaic virus into new areas, a research report has concluded.

But while the forager bees are not likely to transmit the disease, the hive components themselves (boxes, hive stands) and vehicles could carry infected soil/plant material which needs to be managed.

The Australian Honey Bee Industry Council (AHBIC) highlighted the findings in a communication to its members, based on information from a Hort Innovation study.

Cucumber green mottle mosaic virus (CGMMV) is a virus that affects cucurbit plants and was first found near Katherine in the Northern Territory in 2014, then later at Charters Towers in 2015 and Bundaberg in Queensland in 2017.

In November 2021, a meeting in Darwin of beekeepers and the Northern Territory Department of Primary Industries updated beekeepers on the latest research, in particular the question of whether the long range movement of bee hives for pollination services could introduce CGMMV into new areas.

Northern Territory government research entomologist Mary Findlay-Doney relayed information to the AHBIC saying the short answer was there was only a small window of time after initial exposure to the plant virus that forager bees were able to transmit it.

"We recommend a resting period of one month after hive exposure to CGMMV positive plants," Ms Findlay-Doney said.

"Managed pollinators and their ability to transmit CGMMV is just part of broader understanding of managing farm and apiary biosecurity."

She said honey bees that have been exposed to CGMMV are not the most significant source of CGMMV.

"It is a plant virus that is most frequently introduced in seed/infected planting material and can be moved in soil, plant material or on contaminated equipment," she said.

"Apiary equipment (boxes, hive stands) and vehicles could carry CGMMV infected soil/plant material and also need to be managed."

According to a NT government fact sheet, sterilisation of vehicles, equipment, plant trays, tools and footwear with potassium peroxymonosulfate or freshly prepared 1 per cent sodium hypochlorite (NaOCl) bleach can help limit the spread of CGMMV.

"Repeated use of chlorine solution will damage hive tools, bee suits and boxes. It is recommended that you rinse these items with fresh water after the completion of treatment," the sheet said.