Biological Control of Eucalyptus Gall Wasp - Conference Distributing Natural Enemies of Gall Wasps Worldwide

November 24, 2008 14:03

Week-long conference attended by researchers and commercial forestry experts who deal with cultivation of trees for the papermaking industry and other wood products such as biological fuel.

Biological Control of Eucalyptus Gall Wasp - Conference Distributing Natural Enemies of Gall Wasps Worldwide

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Three tightly sealed packages have made their way eastward to China and India and westward to Italy. Each package contains young branches of eucalyptus trees infested with the eucalyptus gall wasp. The galls on the branches also contain eggs of two varieties of parasitic wasps - the natural enemies of the eucalyptus gall wasp. The packages were accompanied by official documents and were in the trustworthy hands of the scientists who participated in the first international conference on control of the eucalyptus gall wasp, organized by KKL-JNF and the Vulcani Institute for Agricultural Research. The week-long conference was attended by researchers and commercial forestry experts who deal with cultivation of trees for the papermaking industry and other wood products such as biological fuel. The lectures and seminars focused on the world-wide battle against the tiny eucalyptus gall wasp, which has spread from Australia in recent years and has appeared in commercial eucalyptus groves throughout the world. The wasp lays its eggs in the new branches or in the veins of the new leaves, causing growths known as galls. The galls inhibit the development of mature trees and have caused wilting of millions of eucalyptus saplings and young trees in nurseries. Distributing the Natural Enemy of the Gall Wasp After an intensive week of study and field observations, Professor Zvi Mendel of the Vulcani Institute instructed participants who came from twelve different countries on how to propagate and release two types of parasitic wasps that eradicate the gall wasps during their larval and pupa stages and prevent them from multiplying beyond control. "In Israel we began to release the parasitic wasps - the natural enemy of the gall wasp - 15 months ago and we can already see that the trees in the infested areas are beginning to recover. We released several dozen wasps in each infested area, and they have begun to multiply and do their work. These plastic boxes contain young eucalyptus branches from the hothouses in the Vulcani Institute, all of which are infested with galls caused by two types of wasps. Parasitic wasps that are natural enemies of the gall wasps have also laid their eggs in the galls, and will hatch within a few days." Both the gall wasps and the parasitic wasps originated in Australia where a natural balance exists between the two species, and therefore the gall wasp does not constitute a threat to the eucalyptus forests in Australia. The gall wasps have spread throughout the world in recent years, and with the absence of natural enemies such as the parasitic wasps that exist in Australia, they have spread alarmingly fast. Modest estimates place the damage at tens of millions of dollars each year. That estimate may well reach hundreds of millions if no solution is found to the gall wasp. "The research in Australia in which natural enemies of the gall wasp were found was funded mainly by friends of KKL-JNF Australia," explained Professor Mendel to participants at the conclusion of the conference. "We were lucky that KKL-JNF in Australia not only funded this expensive research, but also connected Israelis with the right people and factors that have mobilized to help us in our study. The most predominant of these is the head of the National Entomological Museum of Australia, Professor John La Salle. I doubt whether we would have achieved this success without the help of Australian KKL-JNF." Indeed, the contribution of Joe Krycer, State Director of JNF Victoria, Australia, to this project was so great that the research team decided to name after him one of the natural enemies of the gall wasp. The discovery of the natural enemies of the gall wasp three years ago was earthshaking news to foresters throughout the world. At the time there were severe attacks of the gall wasps in the huge areas of eucalyptus groves of Asia, Africa, South and North America, and the Mediterranean and no chemical or physical means of control proved to be effective. Professor Mendel spoke about the importance of applying his discovery at the start of the unique international conference. "The more I talk with the people who came here fromThailand, India, South Africa, Kenya, Uganda, Italy, Brazil, China, Turkey or Australia, the more I realize the vast importance of finding a solution to the difficult problem of the gall wasp in the eucalyptus groves. Many of our guests are surprised that we in Israel took upon ourselves the task, despite the fact that there are no commercial eucalyptus groves here except those planted for beekeepers in the Israeli honey industry. People are filled with admiration that we have succeeded in giving them the only known solution today and are teaching them how to apply it. This conference is perhaps a starting point for an international platform that will deal with this issue on a permanent basis. In any case, the current problem now exists everywhere. Meanwhile, we know that ten sub-species of the gall wasp have spread from Australia throughout the world - nine of which have spread from Australia in the last decade. This is not surprising if we remember that we are talking about insects that are only a millimeter to 1.5 millimeters long, and the parasitic wasps that attack them are no larger." Usually insects used for fighting agricultural pests are reproduced on a permanent seasonal basis by an industry at Kibbutz Sde Eliyahu that specializes in the production of insects for biological pest control. However, it is not commercially viable to produce the parasitic wasps for controlling the gall wasp because only several dozen parasitic wasps will reproduce in nature. The Vulcani Institute therefore assumed the task of reproducing several dozen parasitic wasps from Australia, and will continue the reproduction process as long as factors throughout the world need help in eradicating the gall wasp. This help is given for free while Israel continues to offer support to research experiments in controlling the gall wasp in other countries. Additional help was given through the research by Professor Miktad Doganlar from the Mustafa Kamal University in Turkey, who was also among the conference participants. "All we need to raise the next generation of parasitic wasps that control the gall wasps are young eucalyptus saplings infested with galls, grown in hothouses under conditions of controlled temperatures and humidity. The parasitic wasps or infested eucalyptus branches in which they have laid their eggs are then introduced. After about two weeks you simply take the infested trees out of the hothouse and place them in the eucalyptus groves that are to be treated. The parasitic wasps will hatch, establish themselves in the grove, and reproduce. They will gradually keep the gall wasps under control until they cause only minimal damage to the trees," continued Professor Mendel to the scientists looking at the plastic boxes filled with eucalyptus leaves that they had just received. New Aspects of Commercial Forestry Research Genetic Engineering Research The guest experts also received explanations regarding additional aspects of commercial forestry research being conducted in Israel. Dr. Ziv Shani from the Israeli Company "Futuragene" presented genetic engineering research in which a particular gene was introduced into eucalyptus tree cells that elongates them, thus accelerating the growth of the tree. This research is extremely important to the wood and wood products industry. These genetic changes enable genetically treated trees to produce 300 times the amount of wood for industry than non-treated trees in any given forest area! In addition, the genetic changes result in improved quality of the wood fiber so that paper produced from the wood is stronger. This successful research has meant commercial cooperation with paper manufacturers in Brazil, Thailand, and China who send tissue cultures of selected trees from their groves. These cultures undergo a genetic improvement process in Israel and are then returned to their countries of origin for developing the next generation of fast-growing saplings. Eucalyptus Research for Honey Production Professor Dan Iscovitch from Tel Aviv University reviewed several varieties of eucalyptus trees for alleviating the shortage of flowers for honey production and for creating pollen for nurturing the bees in the hives. He explained how the honey industry in Israel had collapsed after the drought of 1975 and the search for a constant supply of nectar and pollen that began at the time. "We located varieties of eucalyptus that flower during the time of year in which there are no other natural flowers. The eucalyptus was chosen, among other reasons, because it is resistant to relatively dry conditions and flowers during the summer when citrus trees and other fruit trees do not flower. We found that despite the fact that it flowers one month each year, it is the best for producing nectar. Each of the flowers of that type of eucalyptus tree produces four cubic centimeters of nectar while it blooms, and in the morning bees can be seen gathering around the flowers while they are still closed, waiting for the petals to open." Eucalyptus Research for Ecologically Neutralizing Polluted Soil The only topic that caused raised eyebrows and controversy among some of the participants in the course was presented by Dr. Pinhas Fein from the Vulcani Institute. Dr. Fein, together with other scientists, is conducting research on use of eucalyptus trees for ecologically neutralizing polluted soil. The research, which is at an advanced stage, combines chemistry and botany and involves eucalyptus trees that absorb heavy poisonous metals such as cadmium, nickel, lead, mercury, and chrome from the soil and transfer them to the leaf tissue and branches at the top of the tree. There were many questions regarding the repercussions of absorbing heavy metals into the plant tissue, including the question of what should be done with fallen eucalyptus leaves saturated with heavy metals and the question of whether the metals penetrate the flowers, the nectar, and pollen, and are therefore liable to be incorporated into honey that would be marketed to consumers in the future. Since the research is experimental and the process is on a limited scale, its partial success has no practical positive or negative repercussions at this point. But the questions posed by forestry experts mean that research must provide answers on significant repercussions before the process of purifying soil polluted with heavy metals is used on a broader scale. At the end of the conference the message of Efi Stenzler, KKL-JNF World Chairman was conveyed to the guests. "Diseases and pests do not take national borders into consideration. Only cooperative efforts of researchers and foresters such as this workshop can bring about environmentally-friendly solutions to the problem of the gall wasp. I see this initiative as having additional importance. It is an example of international cooperation that enables us to deal with forestry and environment issues in the future. We, the members of KKL-JNF, are happy to create a broader international framework through which we can work together on dangers that threaten forests throughout the world. I see you as the honorary ambassadors for that task." The participants in the conference returned to their respective countries armed with a great deal of new knowledge and information as well as with a natural enemy that will save the eucalyptus forests throughout the world from potential extinction. Sponsored content

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