Scientists battle against mighty bee mites

By Dewi Anggraeni

MELBOURNE, Australia (JP): All honey consumers in the world should note this: behind every drop of honey there is a scientist. So many things can go wrong with the honey industry, which could wipe out honey for good from the breakfast menu or the list of cooking ingredients. Thanks to scientists and technologists, such dire circumstances have so far been avoided.

In the course of its journey to reach us, the end consumers, factors as intangible as bad marketing strategy can prevent or delay its arrival at our table or kitchen. And real things, though not much more visible, such as mites, can very well nip the journey in the bud, so to speak.

Only by using very expensive chemicals can commercially-run hives be kept reasonably healthy.

Recently, a pinhead-sized mite given the name of Varroa jacobsoni, varoa mite for short, decimated wild honey bee populations in Europe and the U.S.A.

In Irian Jaya, Tropilaelaps clareae, or the Asian mite, as the beekeepers call it, systemically destroyed the beekeeping industry within two years.

When both mites reared their heads in Papua New Guinea, alarm bells rang in Australia. Australia is the world's fifth largest honey exporter. Honey production itself is worth US$160 million annually, and another $6 million comes from the packaged bee export industry. Not only on honey production do the mites spell disaster. Wild honey bees are crucial for pollinating many crops. In Australia, at least $1.2 billion worth of crops would go down the drain without them.

In 1989, Dr. Denis Anderson of the Australian Center for International Agricultural Research began working on research projects to control the damage. The $400,000 worth of three year projects, $277,000 of which was funded by the center, began in April 1993. They are conducted jointly by Australia's Commonwealth Science and Industrial Research Organization and Indonesia's Animal Husbandry Office.

Determined to eradicate the mites, the team then discovered that the varroa mites were not breeding in the European honey bee colonies in Papua New Guinea. The researchers believe these mites may be a different strain from those that have infested the bee colonies in Europe and the U.S.A.

Now efforts are concentrated on the Asian mite, which without doubt is devastating the European honey bee populations of the Papua New Guinea highlands. The mites are being carried from colony to colony by the honey bees themselves, especially feral colonies. Contact with them can kill a large colony within three to six months.

The researchers use the very destructiveness of the mite as their springboard. It seems that the destruction of the existing honey bee population is so total that no mites survive. So if reinfection can be prevented, after the mites have passed through, it should be possible to reintroduce honey bees and rebuild colonies.

However, letting the mites totally wipe out the honey population can be a very costly strategy, thus unacceptable both in Papua New Guinea and Irian Jaya. It might mean 10 years without a beekeeping industry. Experiments of an alternative project showed that the mites can be eradicated by using higher than normal doses of acaricides continuously for at least six months. In practice, this strategy also is flawed. Apart from the prohibitive costs, it raises chemical residues in the honey to unacceptably high levels.

The researchers then found a ray of hope for yet another strategy -- the life cycle of the mite itself. Bees grow from eggs to larvae through to young adults in brood cells within the bee colonies. The mites, as it turned out, can only feed on bee larvae within the brood cells. To invade another colony they must be carried by an adult flying bee. However, as they cannot feed on adult bees, they can only survive on them for two or three days at the most.

A young bee emerging from its cell cannot leave the colony for several days. In the meantime, any mite that has been feeding on the larva will die unless it finds a new larva. However to leave the hive, the mite must transfer to another older adult bee. If it does not find a larva in time, it will die en route. Thus, in general, the mite is not in the spreading mode.

The mite's spread to other colonies probably happens by accident. When different bees look for nectar on flowers, these mites transfer from carrying bees to bees from clean colonies. Sometimes it also happens when a disoriented carrying bee inadvertently visits a clean colony.

Based on these discoveries, it is possible to eradicate the mite by isolating infested colonies from others, then removing all brood cells for four to five days. When clean brood cells are reintroduced, the mites' reproductive cycle will have been broken, so the young larvae cannot be infected from within the colony. A logistical problem with this method is that all colonies within a village would have to be cleaned at the same time.

Dr. Anderson and his team are working to obtain cooperation between government authorities in Papua New Guinea and Irian Jaya.

Another method involves the registration of beekeepers so the authorities can ensure that they are issued with acaricides. This would guarantee that the registered colonies would survive, and in the meantime all wild and non-registered domestic colonies would die from infestation. Then the surviving registered colonies would be treated with higher-than-normal doses of acaricides to eradicate the mites from both Papua New Guinea and Irian Jaya.

All beekeepers in Irian Jaya will be involved in the trial eradication program. When the eradication is complete, together with the staff of the provincial Animal Husbandry Office, they will make sure that bees introduced to Irian Jaya come only from countries that are free of bee mites and serious diseases.