Dialogue: Plus side to spread of destructive mite

A new Varroa mite alert has resurrected fears in the beekeeping industry. But, writes NARENA OLLIVER*, it may not be all bad news.

Many people who live in the northern part of the country will have noticed fewer honey bees around as the Varroa mite spreads relentlessly.

In just over one year, the mite is believed to have killed all the feral bee colonies in Auckland.

In up to six years, it is predicted that the wild bees, the feral honey bees |- which may make up as many as a third of the total number of honey bees - will be all but wiped out.

What impact will this have on the New Zealand environment?

What impact will it have on our gardens and farms, on the bush and on the birds?

After the initial flurry of activity and plethora of dire predictions, there has been little commentary other than from home gardeners, who worry about unpollinated fruit trees and vegetables such as squashes, courgettes, capsicums and aubergines.

However, it may not be all bad news, and the decision not to pursue a costly eradication programme was probably the most sensible decision to have come out of the Government of late.

Varroa was first identified at the turn of the century living on an Asian honey bee species called apis cerana.

No one knows how or when it jumped species to the European honey bee, apis mellifera, but by the 1990s it was widespread throughout the world. New Zealand was one of the last countries to acquire it.

Most plants need an agency, a pollinator, to reproduce. Flowers are adapted in diverse ways to ensure their pollination, either by self-pollination or by the aid of wind, water and some animals, birds and innumerable insects, including moths, butterflies, flies, beetles and, of course, bees.

There are around 45 species of bees in New Zealand. They are split into two groups, social and solitary bees.

All social bees were introduced to New Zealand. They include several species of bumble bees and honey bees. Bumble bees were introduced to ensure the more adequate pollination of red clover to augment seed production, and the honey bee to produce honey and pollinate white clover.

Native bees are solitary. They do not live in groups and do not make honey, but are important pollinators of native plants. They are the ones that are seen only in summer and look a bit like flies. Many make burrows in banks for their offspring.

The solitary native bee is not susceptible to the Varroa mite, which is good news for our native flora.

Neither is the bumble bee, which is good news for the home gardener and for farmers and horticulturists, especially as the bumble bee figures largely in the pollination of plants grown in glasshouses.

Indeed, native bees and bumble bees, without competition from feral honey bees, may well flourish.

The Varroa mite is not really all bad news for the beekeepers either. Although they have suffered economic loss from damage to the country's honey bee export industry, they will be able to maintain their hives with the use of chemicals, and probably command higher prices for their pollination services to commercial growers, seed growers and kiwifruit growers.

However, it has been found that a relatively high number of flies, beetles, bumble bees, and solitary bees visit kiwifruit flowers, although they are very susceptible to sprays.

There may be some impact on the seed-eating introduced birds, but,otherwise birds may benefit, especially the nectar-eating birds.

Australian scientists have done a lot of work on competition between honey bees and their nectar-eating birds and have concluded that honey bees are detrimental to bird life.

Little research has been done here, but Maori, as recorded by Elsdon Best, thought that, together with the introduction of the tree-climbing rat, the introduction of the honey bee had the most impact on our birds.

So, if you see more tuis and bellbirds around in future, perhaps one should thank the Varroa mite.

* Narena Olliver was a member of the East Coast Conservation Board for six years.