The small-scale trial took place earlier this year on two privately owned Gala orchards in Kent (less than 1km apart) and was led by Norman Collett technical director Nigel Jenner and Shropshire-based CJ Wildlife (CJW) pollination specialist Robin Dean.
Dean, speaking at last month's National Fruit Show near Detling, Maidstone, revealed that the trials showed "significant differences" in the firmness of the fruits. The trial orchard's fruit is 1.6kg (around 15 per cent) of pressure above that of the control orchard.
He added that, while Streif Index tests revealed that fruits from the mason bee-pollinated orchard picked a bit later in the season, overall "the effects of the Mason bees were quite apparent".
He said: "The trees had fruit with fantastic consistency of set, wonderful colour and ripening synchronicity ... but the real talking point was the difference in firmness of the fruit. Such a large variance was wholly unexpected."
Researchers also checked the results against those of 12 other orchards. But they found that the trial orchard was still 1.1kg above the mean of 9.7kg.
Dean said: "These figures tally with research work done in New Zealand showing a correlation between good pollination and long-term storage potential.
"Granted, increased pollination efficacy will mean the grower has to deal with increased thinning, which in turn means higher labour costs early in the production process, but the potential of cost savings in storage and the higher production figures are likely to offset this by a considerable margin."
Jenner said: "This is the most exciting development in optimising crop yield that we have seen for a long time."
Norman Collett markets fruit for producer organisation Mid Kent Growers and was keen to investigate alternatives to the honeybee, declining numbers of which threaten the sustainability of horticulture.
The EU-sponsored, five-year ALARM (assessing large-scale risks for biodiversity with tested methods) project, which finished last year, placed the reduction of pollinators at approximately 30 per cent over the past decade in places where data exists.
The red mason bee is possibly the best alternative to the honeybee as it is native to the UK and Europe, with a proven track record in eastern Europe and other parts of the EU.
Other members of the Osmia family have been used in Japan and in southern California. CJW has spent considerable resources developing a propagation system for the red mason bee, which lives for just five weeks.
Dean said: "CJW has spent four years developing viable propagation systems for red mason bees and can now say with confidence that the technical issues have been cracked. This means these bees will be available as an orchard-management tool for the UK top fruit industry, without the pitfalls of using an imported bumblebee species."