Why use Delfin® WG for the control of Lepidoptera larvae

Why use Delfin® WG for the control of Lepidoptera larvae

Delfin® WG is a biological insecticide used for the control of Lepidoptera larvae. Delfin® WG is specific to Lepidopteran insects and is safe to non-target organisms and therefore has no negative effects on naturally occurring beneficial insects or introduced macro biologicals, making it ideal for use in an integrated pest management programme. Delfin® WG contains no harmful residues and has a one-day harvest interval. Delfin® WG also has a unique mode of action, making it a useful product to use in pest control programmes to help prevent resistance developing in insect populations.

Delfin® WG has a very small particle size, meaning good suspensibility and distribution when mixing and applying the product. This ultimately leads to better efficacy of the product since it relies on ingestion by the pest to work. Finally, little or no loss of Delfin® WG is expected if allowed to dry for four hours before rain or overhead irrigation.


What is Delfin® WG?

Delfin® WG is a biological insecticide used for the control of Lepidoptera larvae. The product consists of a bacterial preparation containing the spores and crystals of Bacillus thuringiensis subspecies kurstaki.


Delfin® WG is an approved insecticide for professional use.

 Delfin® WG is an approved insecticide for professional use.


What is Bacillus thuringiensis kurstaki (Btk)?

Bacillus thuringiensis kurstaki (Btk) belongs to a group of bacteria used as a biological control agent against Lepidoptera insects (moths and butterflies). Bacillus thuringiensis kurstaki (Btk) is one of the oldest biopesticides. It was first commercialised in 1938 and has since grown to become one of the most widely used biopesticides in agriculture.  Btk is a Gram-positive bacterium that can be found in a great diversity of ecosystems including soil and water, dead insects and leaves. The spore forming bacterium produce crystalline proteins. Once ingested by Lepidopteran larvae these crystalline proteins have insecticidal properties.  


How does Delfin WG work?

The insecticidal activities of Delfin® WG are attributable to the crystals (crystalline proteins) that are produced during sporulation. Once ingested by the caterpillar, the crystalline proteins dissolve in the insect’s mid-gut due to the highly alkaline environment. This releases a Protoxin that is then activated by the insect’s digestive enzymes. The activated Cry toxin (δ-endotoxin) binds to specific receptors in the insect’s midgut causing a pore to form. The pore causes the insect’s gut contents to leak into the bloodstream of the insect, leading to osmotic shock and gut paralysis. This leads to death of the caterpillar within one to three days. Delfin® WG requires ingestion by the caterpillars in order to be effective.


What stage of the lifecycle does Delfin® WG control?

Delfin® WG works against the larval stage, i.e. caterpillars of Lepidoptera insects (moths and butterflies). It has no known effects on the eggs, pupae or adults.


What caterpillars does Delfin® WG control?

Delfin® WG can be used for controlling a wide range of Lepidoptera species. The following list are examples of caterpillars that can be controlled by Delfin® WG: codling moth (Cydia pomonella), summer fruit tortrix (Adoxophyes orana), winter moth (Operophtera brumata), apple ermine (Yponomeuta malinella), lackey moth (Malacosoma neustria), cabbage moth (Mamestra brassicae), tomato looper (Chrysodeixis chalcites), silver Y  (Autographa gamma), European grapevine moth (Lobesia botrana), European grape berry moth (Eupoecilia ambiguella), Pieris spp., Plusia spp., Mamestra spp., garden pebble (Evergestis forficalis), diamondback moth (Plutella xylostella), box tree moth (Cydalima perspectalis) and other caterpillar species.


Can Delfin® WG be used to control winter moth (Operophtera brumata)?

Winter moth (Operophtera brumata) caterpillars are one of the pests that Delfin® WG can be used to control. Please see the product label and the HSE website for a full list of crops that Delfin WG can be used upon.


What damage does winter moth cause?

Winter moth causes damage to many different crop types in the UK, including crops such as apples and pears. The young caterpillars hatch in spring and feed within the blossom on trees, damaging the developing fruit. Extensive damage to fruit trees can reduce yield.


How can I identify winter moth (Operophtera brumata)?

Winter moth adults have a wingspan of 22-28 mm and vary in colour from grey to yellow to beige to brown. The patterns on the wings are often bands of dark brown. The female adults are wingless and can’t fly, whereas the male adults have wings and can fly.

Winter moth caterpillars range from 2.5 mm after hatching to 19 mm when fully grown and are green in colour. Winter moth caterpillars have two prolegs.

Winter moth (Operophtera brumata) larvae

Winter moth (Operophtera brumata) larvae


What is the life cycle of winter moth?

Wingless female adult winter moths emerge from pupae and climb up the bark of trees laying their eggs on branches from November to April. Each female lays around 100 eggs. The winter moth eggs hatch around bud burst and the larvae start to feed. The caterpillars complete feeding by early June. They then drop to the soil to pupate.


What crops can Delfin® WG be used on?

Delfin® WG can be used on a wide range of crops. The following are examples of the crops that Delfin® WG can be used on: apple, pear, grapes, pepper, aubergine, tomato, cucumber, courgette, cauliflower, broccoli, calabrese, cabbage, brussels sprouts, kale, ornamental plants, herbs, cherry, strawberry, raspberry, blackberry, blueberry.  For a full list of approved crops and cropping systems please see the product label and the HSE website.


How to apply Delfin® WG?

Delfin® WG should be applied at a rate of 0.75 kg/ha when larvae are first observed in the crop. Fill the spray tank with half of the required water and start agitation. Add the required amount of Delfin® WG to the spray tank and continue agitation. Fill the spray tank with the remaining water. Apply the mixture straight after preparation.  Do not leave the prepared mixture for more than 12 hours before use. Delfin® WG should be applied in a water volume between 150 to 1500 L/ha. The amount of water used will depend on the crop and its development stage. It is important to ensure that good coverage is achieved, as the product needs to be ingested by the larvae, however it is important not to spray until runoff.


When should I apply Delfin® WG?

Delfin® WG should be applied in time for egg hatch as it is most effective against smaller/younger caterpillars.


How do I know when to apply Delfin® WG?

Delfin® WG should be applied when egg hatch is just about to occur. Timing will be dependent on target Lepidoptera species and climate. The best way to judge when application of Delfin® WG is required is to know your insect pest and carefully monitor for the presence of eggs and/or use models such as RIMPRO that predict when egg hatch is likely to occur, taking into account other factors such as local climate.


How many times should I apply Delfin® WG?

Delfin® WG can be applied between three and six times per crop, depending on the crop it is being used on. For best control, repeat applications are recommended. Please note it is a legal requirement to adhere to the product label of Delfin® WG.  For further information on number of permitted applications please see the product label.


What is the recommended interval between applications of Delfin® WG?

The minimum interval between applications of Delfin® WG is seven days. Please note that the minimum spray interval is a legal requirement and must be adhered to.


How to store Delfin® WG?

Delfin® WG should be stored in a cool, dry, frost protected place and kept out of direct sunlight. Avoid temperatures over 30°C.


Can Delfin® WG be used in organic systems?

Delfin® WG can be used in both organic and non-organic cropping systems. Delfin® WG has Organic Farmers and Growers approval (OF&G).


Is Delfin® WG safe to use?

Delfin® WG is safe to use for both humans and any non-target organisms. The bacteria in Delfin® WG are very specific to Lepidoptera insects.

For further information on Delfin® WG please click here.


Please note that Delfin® WG is an approved insecticide for professional use and can only be recommended by a BASIS qualified advisor. All product label restrictions must be adhered to.  

Back to blog