Scientists are working to improve our agricultural products by researching why bees are being threatened by a mite, how our wines can become more globally competitive and improving the fruit and flower industries
Sean O’Connor
I watched a bee working my garden the other day. In future, I may not be so lucky. Over the past three decades an ectoparasitic mite called Varroa has almost totally destroyed many of the world’s wild bee colonies. An unwelcome arrival in South Africa in 1997, Varroa has now spread nationwide, threatening the existence of our wild and commercial honeybee populations.
The implications are profound. The predicted elimination of bees from the local environment will have catastrophic knock-on effects. Bees are the unsung heroes of agriculture, contributing an estimated R3,2-billion a year via pollination of crops and commercial bee-keeping, and are responsible for 100 000 jobs. Some Karoo farmers have already lost up to 75% of last season’s onion crop, while the highly priced bee-keepers who arrive with hives to pollinate their fields also face disaster.
At present, scientists are still trying to identify the link between the Varroa mite and the many viruses it triggers in bees. They have discovered that the mite’s bite initiates a set of physiological reactions, including weight loss, wing defects, growth deformities and susceptibility to secondary infections, which it also causes. Most significantly, Varroa activates a range of dormant viral reactions, including acute paralysis virus, a fatal variety that has already affected our bee population.
Behind the local effort to limit the impact of Varroa is Professor Sean Davison, a virologist in the microbiology department at the University of the Western Cape. Equipped with funding from the Deciduous Fruit Producers’ Trust, the South African Subtropical Fruit Growers’ Association and the Western Cape Beekeepers’ Association, which is matched by Technology and Human Resources for Industry Programme, he and a team of postgraduate researchers are involved in the genome sequencing of a range of honeybee viruses. This will enable rapid identification of mite-induced bee viruses, and the timeous intervention to control their spreadof pesticides administered via an adhesive strip placed beneath the hive. Wild honeybees will have to fend for themselves.
Bee viruses are unique. According to Davison, they have a set of nucleotides for initiating the synthesis of preotins, which are different from any other organism. That they should first be discovered in the 21st century is very rare and, understandably, not much is known about them. The primary goal of Davison’s research is to develop a system for virus identification based on the viruses genome sequence. Reverse Transcriptase PCR (polymerase chain reaction) primers have already been used for the molecular identification of acute bee paralysis virus and black queen cell virus, while work is well under way in designing and testing PCR primers for sacbrood virus, Kashmir bee virus and chronic paralysis virus. It’s clearly not a good time to be a bee.
But to be a scientist is another matter entirely. Applied research, with its focus towards benefiting industry and society, seems to be finding its feet in this country, through the unique relationships and incentives being matched between the state and industry. Our knowledge economy is clearly developing, with microbiology and applied biotechnology as two of its fastest growing fields. ”Although all the virologists in South Africa would probably fit into a large American laboratory,” reckons Davison, a transplanted New Zealander and naturalised local, ”South Africa is a fantastic place to be a scientist. There is a whole continent of viruses here and no one looking for them.”
He is clearly excited by what he calls ”a new culture of research at UWC.” Also being developed in his department is a naturally occurring pesticide, which can be cultivated in a laboratory and easily administered by hand. It was inspired by a peasant farming practice in rural Zimbabwe, where certain insects (a commonly occurring caterpillar Trychoplusia ori) are ground up and applied to crops as a pesticide. Microbiologists discovered that that caterpillar contained a ”very good” virus, according to Davison, which is protected by a unique UV-resistant protein coat. The virus itself contains a gene fatal to its host. This baculovirus, as it is known, does not kill its host quickly enough, as it likes ample time to replicate. Microbiologists at the university are experimenting by removing its ”slow” IAP (inhibition apostosis) gene, so that death would be quicker, resulting in less damage to crops.
”Genes are lost through evolution naturally,” asserts Davison. ”The deletion of a gene does not really amount to interference.” This is a moot point. Interestingly, baculoviruses are already used for pest control in the production of organic-certified food in the United States. That these genetically altered ”biological control agents” are responsible for the perceived ”natural” health of organic produce is an evolving irony: because ”natural” DNA is the material used, microbiologists say they will always remain within the confines of what nature offers. Hence the ”organic” label.
More controversially, Davison suggests the possibility of adding or splicing genes from other caterpillars to the Trychoplusia ori Nuclear Polyhedrosis Virus (ToNPV) in order for it to destroy a bigger range of free-eating worms. At present this is just a theoretical possibility, always subject to extensive testing, trials and impact assessments. However, if it took science this long to discover these viruses, how long will it take before we can determine the effects of tampering with them?
Speaking to Davison, so clearly energised by the possibilities of his field, one feels that public sentiment to genetic modification, competing with a range of other pressing social issues, will never prevent radical science. GM legislation provides an ethical framework that often has little to do with what actually happens inside a laboratory. After all, science is about enquiry, an instinct we can’t do without. Remember, curiosity killed the cat. Perhaps it can save the honeybee.