Love them or hate them, since they were brought to the West in 1770, eucalyptus trees have played an important part in modern forestation. On the plus side, they grow quickly, give plenty of shade and dry the swamps; on the minus side, they’re water-suckers that uproot paths and sidewalks.
Nonetheless, the hardy camaldulensis “Red Gum” strain of eucalyptus is a staple component not just in landscaping and forestry but also industry, where it is a reliable, inexpensive source of wood, cellulose for paper, and oils used to produce cleaning and deodorizing products, food supplements; (such as cough drops), even mosquito repellant.
This resource has been threatened in recent years by a tiny 1mm long parasite, the gall wasp or cynipidae, whose reproductive process invades plants, causing them to form a variety of strangely shaped, colored “galls” that make the leaves drop off and leave trees ravaged and bare.
China, India, Thailand, Brazil, Central and South Africa, and the Mediterranean basin including Israel have all been infested by gall wasps. And the plague is spreading: just last month, at a course on how Israel is fighting the pest – and winning – word came in that cynipidae were identified in Florida and are likely to reach California shortly.
The course, jointly organized by the KKL-JNF Forestry and Development Department and the Department of Entomology of the Agricultural Research Organization (ARO, also known as the Volcani Institute), was held in response to requests from several countries for information to save their commercial eucalyptus groves.
Finding a natural enemy
Eucalyptus researchers and commercial growers from around the world attended a training course on eucalyptus forestry and agro-forestry with an emphasis on two invasive gall wasps and their natural enemies.
“There are 15,000 hectares of eucalyptus in Israel,” says conference co-organizer David Brand, head of the JNF Department of Forestry and Development. “For the sake of comparison, in China there are hundreds of millions of hectares which are used to supply the paper industry. Thailand plants 100 million saplings every year, China plants half a billion every year, in Africa eucalyptus is used by local farmers for fuel. And we weren’t aware of it but in India, eucalyptus is a source of income for hundreds of thousands of private farmers whose livelihood is the paper industry. Yet despite our small size, they told us, ‘You in Israel are rescuing us.'”
Israel entered the gall wasp fray seven years ago after massive damage was caused to Israel’s eucalyptus trees. “JNF and ARO identified the problem early and initiated an international project to find a natural enemy of these wasps,” Brand tells ISRAEL21c.
After an exhaustive two-year search, a team of JNF-funded scientists finally found a biological adversary in Northern Australia, another 1mm long wasp called closterocerus. “We brought them to Israel, quarantined them, and after making sure this natural enemy only harmed cynipidae, we let them loose,” says Brand.
The Israeli solution has a powerful booster in research partner Dr. John La Salle: head of the Australian National Insect Collection at CSIRO, the Commonwealth Scientific and Industrial Research Organization. When the gall wasp reached Florida, he was contacted by the US Department of Agriculture Forest Service, and he advised them to turn to Israel for help.
November’s training course familiarized participants with management strategies concerning eucalyptus cultivation and presented the most up-to-date uses of eucalyptus trees: propagation and use of eucalyptus in nurseries for arid land afforestation and management; disposal of wastewater through irrigation of eucalyptus plantations; and eucalyptus biotechnology.
The group was also given a presentation by CBD Technologies, part of Futuragene, an Israel-US bio-engineering firm that has developed high-performing transgenic eucalyptus for the plantation forest industry that is resistant to cynipidae.
Giving the predators free of charge
“They were stunned by our activity here in Israel. We took them to the north and the south, to see our fight against desertification, commercial forestation, water recycling for irrigation and eucalyptus to provide an ongoing supply of nectar and pollen for bees grazing in seasons where there is no fruit tree flowering,” says Brand.
There are 700 types of eucalyptus in Israel, he adds, and JNF distributes 200,000 saplings a year free of charge for forestation and bee grazing.
Israel is reproducing parasites to eradicate gall wasp at ARO, offering these to other countries free-of-charge, as well as research support. At the end of the course, scientists from China, India and Italy were entrusted with sealed packages containing eucalyptus branches infested with both cynipidae and eggs of two varieties of closterocerus. More requests for such packages will come, believes Brand.
“There were participants from China, India, Kenya, Uganda, Italy, Brazil, Turkey, Australia and South Africa, where the pests haven’t invaded yet, but authorities are convinced they’re not long in coming. The same it true for Kenya; they want to be prepared in advance.”