Insect-pathogenic nematodes measure much less than a millimeter, so you can’t see them with the naked eye. Great care and precision needs to go into the production of these ‘little heroes that are bred for the biological control of a host of horticultural and orchard pests by biocontrol company, Koppert Biological Systems.
More than 30 years’ experience has gone into the selection, breeding and quality control of a specific range of these entomopathogenic or predatory nematodes that help to keep our fruit, vegetables and ornamental crops free of pests without chemical residues. At Koppert, the R&D Department has an ongoing drive to refine both the production process and the design of intelligent packaging systems. The packaging and logistics departments ensure that the microscopic nematodes get to their destinations in good health, ready to carry out their valuable work in so many crops, grown either indoor or outdoor.
It all starts in the microbiology laboratories at Koppert headquarters in the Netherlands where various nematodes, bacteria and fungi are cultivated for the biological control of pests and diseases. The entomopathogenic nematodes are grown in liquid media to give the most consistent quality. The process runs through three phases: first the nematodes are grown in a laboratory flask, then they are placed in a scale-up bioreactor, and finally scaled-up to a production bioreactor. After each and every step, quality control takes places to check purity and to make sure the process parameters follow the normal pattern.
Each nematode species has its own specific medium in which it develops best. A solution of the medium is made in a flask and sterilized in an autoclave to avoid any risk of contamination. Then the nematodes are placed in a nutritious and sterile environment and shaken continuously so that enough oxygen is introduced. Besides essential nutrients, these living organisms need oxygen to thrive and develop and oxygen continues to be added once the solution goes into the bioreactors. A recent innovation has led to an improved recipe: animal proteins were replaced by proteins from plants. This made the process more cost efficient and reduced the ecological footprint of the whole production process.
Samples of the solution in the bioreactors are taken every few days to check the purity. The nematodes need 12 days to develop for each of the three phases. When the production process has reached its end, the nematodes are carefully separated from the liquid by an ultra-fine sieving technique. They need to remain moist when packaged, stored and transported. This is why they are formulated in a special matrix. In this matrix they ‘move’ very little, saving their energy to do their work when they are applied by the grower.
Each of the three entomopathogenic nematodes bred by Koppert have been selected to target specific pest insects and Koppert produces specific strains of Steinernema feltiae, Steinernema carpocapsae and Heterorhabditis bacteriophora. They are selectively applied to combat a wide range of pests such as the pupae and larvae of thrips, the larvae of black vine weevil and several beetles, caterpillars, the larvae of sciarid flies and many others.
Koppert has developed packaging materials and logistic systems that safeguard the conditions right to the end user. Intensive temperature logging takes place along the route to make sure that the nematodes travel in the best possible conditions.
How does it work?
After application the nematodes search for their prey. Once they have found a host insect, they penetrate through its natural body openings or skin. The nematodes then release pathogenic bacteria they carry with them. These bacteria kill the insect and digest the insect from the inside. The nematodes feed on the digested tissues of the dead insect and reproduce in large numbers. The pest insect dies within a few days. The nematodes that emerge then start their search for a new host.
Part of the IPM toolbox
Nematodes are often used as a stand-alone solution for specific pest problems, but they increasingly become a powerful part of IPM solutions together with other beneficial organisms; working together to either partly substitute, and sometimes replace the use of conventional pesticides, to manage pests that are extremely difficult to control and where chemicals fail.