Bumblebees could soon play a dual role in commercial orchards, pollinating blossom while simultaneously delivering biological treatments that combat bacterial disease.
Scientists at the University of Warwick’s Warwick Crop Centre have demonstrated that bumblebees can successfully transport bacteriophages, or phages, to cherry blossom, where the naturally occurring viruses significantly reduce populations of disease-causing bacteria.
Nature’s pollinators become disease fighters
The research focuses on cherry canker, one of the most damaging bacterial diseases affecting cherry production.
“Phages are found almost everywhere in nature, including soil, water and on plants,” said Dr Mojgan Rabiey, plant pathologist at Warwick Crop Centre.
“Unlike viruses that infect people, animals or plants, phages only infect and kill bacteria, and individual phages are highly specific about which bacteria they attack. That means we can select phages that specifically target disease-causing bacteria without harming beneficial microbes around them.”
Delivering protection where it is needed
While identifying effective phages is one challenge, ensuring they reach vulnerable parts of the plant is another.
The idea emerged as Rabiey and colleagues searched orchards for naturally occurring phages capable of controlling cherry canker.
“Many cherry growers already use bumblebees to improve pollination, and I started to wonder whether the bees flying from flower to flower could also carry phages directly to the blossoms we want to protect,” she said.
To test the concept, researchers developed a hive-mounted delivery system that coats bees with a specially formulated phage powder as they leave the colony. The insects then transfer the phages to flowers in much the same way they naturally carry pollen.
Experiments involving both real and artificial cherry flowers found that buff-tailed bumblebees (Bombus terrestris audax) delivered phages to up to 88% of blossoms visited. Once deposited, the phages significantly reduced bacterial populations.
A new tool for biological crop protection
Rabiey described the results as an example of “nature working with nature”.
“Phages are natural enemies of bacteria, and bumblebees are natural pollinators. Bringing those two systems together gives us a completely different way to think about protecting plants,” she said.
The Warwick team specialises in developing phage-based biological controls for bacterial crop diseases and sees the technology as a potential alternative to conventional pesticides and antibiotics.
Research fellow Dr Shannon Greer said the system offers a practical route to commercial adoption.
“Developing the phages is only useful if we can turn them into something that growers can realistically use, and our bumblebee phage delivery doesn’t require specialist equipment to apply,” she said.
“We have shown that the approach works experimentally, and the next step is to begin piloting the treatment with growers.”
Potential beyond cherries
Although the initial work focused on cherry canker, researchers believe the approach could be adapted for a range of crops where flowers act as an entry point for bacterial infections.
The team is already exploring applications in apple and pear orchards, forestry trees and vegetable crops.
“Our long-term goal is to give growers practical, environmentally friendly ways to manage bacterial diseases while reducing reliance on conventional pesticides and antibiotics,” Rabiey said.
The findings were published in Biological Control in a paper titled Bee-mediated delivery of bacteriophage for biocontrol of the cherry canker pathogen Pseudomonas syringae pv. syringae (DOI: 10.1016/j.biocontrol.2025.105922).
