Once the nematodes have found a grub they enter the insect via its natural openings or break in through its skin. When inside the insect they release symbiotic bacteria it has been carrying around inside of it
providing solutions for sciarid and vine weevil pest control. In subsequent years, sales have expanded throughout Europe, North America, Japan and New Zealand. Becker Underwood’s nematodes are now used in a diverse range of applications in horticulture (both protected and outdoor), mushrooms, top fruit, home and garden and turf. In many instances nematodes have become the standard for pest control. For example, plant propagators and mushroom growers experiencing problems with fungus gnats widely use nematodes (Nemasys) in preference to chemical alternatives. In other situations, for example vine weevil in strawberries and slugs in vegetable crops, nematodes (Nemasys L and Nemaslug respectively) are used for their strong efficacy and non-residue characteristics. Beneficial nematodes are found naturally in the soil, although at numbers which are too low to control pest grubs. Heterorhabditis megidis, the species used in Nemasys G, is 0.8mm in length. Beneficial nematodes are very specific on what they attack and this species will only feed on pest grubs. Following application, beneficial nematodes are able to move through the soil to locate the pest insects. They are able to follow chemical cues such as CO2 produced by the pest grubs in order to find them. As long as the soil is not allowed to dry out the nematodes can actively hunt for grubs for four weeks. They will not feed until they find a grub and will die if they do not. Once they have found a grub they enter the insect via its natural openings or break in through its skin. When inside the insect the nematodes release symbiotic bacteria it has been carrying around inside of it. The insect dies from bacterial infection 24-48 hours later. The species of bacteria carried around by the nematodes is specific to the nematode species; they are unable to survive without each other. The bacteria which lives with Heterorhabditis megidis is red in colour which gives the product a red tinge. It is also the red bacteria which give the grubs a distinctive colour once they have been killed, if you find them
Damage to fairways and tee boxes at Lahinch Golf Club in September 2007. Damage is caused by birds digging to feed on the grub larvae
before they decompose.
Advantages of beneficial nematodes for grub control.
• Proven control
• No restrictions, no re entry interval
• Natural product, safe to applicators, turf users and the environment
• Non toxic, no requirement for protective clothing
• No concerns for residue run off
• Can be applied with standard spray equipment (nozzles >0.5 mm, filters removed)
Pest (Phylopertha horticola) biology
The garden chafer (Phylopertha horticola) is the most common turf grub in the UK. It has a one-year life cycle with adults flying in May and laying eggs. Early instar grubs then feed on grassroots near to the surface until cooling soil temperatures make them move deeper into the soil in October. Root feeding larval damage can be bad. Often large areas of turf can be rolled up like carpet due to the roots being severed by the feeding. However, secondary damage is often more devastating, with crows, badgers and foxes digging at the turf to feed on the grubs. Nemasys G should be applied between the end of July and the end of September, when soil temperatures are
higher than 12°C. This allows the beneficial nematodes to target the small grubs when they are feeding near to the soil surface.
A number of factors have come together to open the market to using beneficial nematodes for turf pest control, such as an increased awareness of the risks of non-target effects on wildlife and turf users of the chemicals, as well as legislative restrictions. An example is the withdrawal of the active ingredient Gamma-HCH (active ingredient in products such as Lindane and Gama-col Turf) that was removed from the UK market at the end of 1999. Merit™ is only available in granule form and can be difficult to apply evenly at the low application rate of 3g/m2
. Chemicals
are also limited in their usage, for example Merit™ can only be applied once a year. There has also been a reduction in the cost differences between the few remaining chemicals and the previously too expensive beneficial nematodes.
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