Page 47 - SA Fruit Journal VOLUME 14

What are EPNs?Entomopathogenic nematodes are a group of nematodes (round worms) that kill insects. The term entomopathogenic has a Greek origin en- tomon, refers to insect, and pathogenic, which denotes causing disease. Although many other parasitic round worms cause diseases in living organisms, entomopathogenic nematodes are specific in only infecting insects. EPN live parasitically inside the infected insect host, and are therefore described as endoparasitic. They infect many different types of insects of which some stages are in contact with the soil, like the larval forms of moths, butterflies, flies and beetles as well as adult forms of grasshop- pers and crickets. EPN have been found all over the world in a range of ecologically diverse habitats. The most commonly studied EPN are those that are used as biological control agents Steinernematidae and Heterorhabditidae.What is Biological Pest Control?Biological pest control is the reduction of pest populations by using natural enemies. It is im- portant because crop pests become resistant to chemical pesticides. It thus forms an integral part of the integrated pest management (IPM) approach.How are bio-control agents found?The first step is a survey of the natural enemies of the target pest. Researchers observe the natu- ral cycle to make sure that the biological control agent does no other damage. Then it can be reared and released in large numbers.EPN - our Biological Superweapon? EliSE-MariE StEEnkaMPWhen Matthew addison originally started thinking about using entomopathogenic nematodes (EPn) to treat codling moth infested wooden fruit bins, he never dreamed that it could possibly turn out to be a Biological Superweapon that could potentially save the deciduous industry millions of rands andin the process spawn a vast scientific research network.Ten years ago, Addison, Crop Protection Manager at HORTGRO Science, had R30 000 funding but no one to take the re- search further. A great believer in biological control as a fundamental aspect of integrated pest management he realised the potential, but was at a loss as to how to proceed.Dr Antoinette Malan, then Principal Plant and Quality Officer at the National Depart- ment of Agriculture, stepped in. Malan had at that stage, in an attempt to continue Nematol- ogy at the Stellenbosch University, replace re- tired Nematologist, Prof. Bertus Meyer.“Even though I am a Nematologist, I didn’t know anything about EPN. Nobody knew anything about them as it was a totally different concept. I had no one to ask, no one to train me. It was new to us all,” says Malan.Nematodes are among the most ubiqui- tous organisms on earth. They occur in virtu- ally every possible environment, either as free- living nematodes or as parasites of vertebrates and invertebrates. There are many different kinds of nematodes, but the ones creating the buzz are the insect-parasitic or entomopatho-EPN infective juveniles.genic nematode or just EPN for short. EPN at- tack and feed only on insects.Malan was fascinated. She got on the Internet and started researching the matter. She read almost every paper she could find and connected with international researchers. She soon found herself on a plane heading for the University of Florida, USA, to train and learn with Dr Khuong Nguyen. “He taught me everything: how to identify them, how to find them in the soil, and all the other research techniques.” Another big help was Prof. Ralf- Udo Ehlers, then based at the Christiaan Al- berts University of Kiel, in Germany.Back in Stellenbosch Malan found an en-thusiastic student, Jeanne de Waal, who was willing to take on EPN and eventually com- pleted her MSc and PhD under Antoinette’s guidance. “Together we did research and taught ourselves.”It helped that EPNs are what Malan calls “model organisms”. “I previously worked with plant-parasitic nematodes – notoriously difficult to study. EPN are exciting and highly satisfactory to work with. We were very mo- tivated.”EPN exiting from a Codling Moth pupae.In 2003, the industry funded a survey of local EPN. The survey was important as nothing of the local EPN occurrence and distribu- tion was known. The survey was successful and during the following year a project was launched that investigated the use of EPN for controlling codling moth larvae in fruit bins. During this time Citrus Research In- ternational also came on board and research was expanded to include false codling moth, mealy bug, and the banded fruit weevil. These positive results made it possible to develop culture methods for local EPN species and launch investigations into their physiology and temperature tolerances.TEGNOLOGIE44 FEB | MAART 2015