May 25, 2023

Tackling caterpillars with PATS-C and DELFIN® WG

Damaged ornamental plants are soon unsaleable. Caterpillars are therefore taboo. With DELFIN® WG, growers have a proven product of keeping pest pressure manageable. IPM & Pollination Specialist Koen Merkus advises to start applying as early as possible in the season.

DELFIN® WG is controlling caterpillars of the tomato looper (Chrysodeixis chalcites), bright-line brown-eye (Lacanobia oleracea) , cabbage moth (Plutella xylostella), Tuta absoluta and box tree moth (Cydalima perspectalis). The smaller (=younger) the caterpillar, the greater the effect of this bacterial preparation. Small caterpillars, in fact, need to eat less of it before the toxic effect eliminates them..

Calculating by yourself

Koen: "If growers observe moths when monitoring, they can calculate when the first eggs will hatch. That's a good time to apply DELFIN® WG."

Bacillus thuringiensis

DELFIN® WG is a Bt product. Bt stands for Bacillus thuringiensis, the oldest and best-known biological crop protection agent. DELFIN® WG contains the subspecies kurstaki. Each subspecies has a different toxin profile and therefore a different effect on caterpillars, making the agents suitable for alternating with each other. Bt agents have no side effect on beneficial insectsand bumblebees.

Good coverage

Because caterpillars need to ingest DELFIN® WG through feeding, Koen emphasizes the importance of proper application. "The better you spray the leaves, the greater the effect," he says. He points out a significant advantage of DELFIN® WG in this regard.. "Compared to other products, the particle size is very small. Particles are the components that contain the spores and crystals. Because these particles are so small, they spread more easily over the leaves, ensuring better contact with caterpillars.."

Deadly for caterpillars

When caterpillars eat the leaves, the Bt crystals are made into toxins in their digestive tract that break down the digestive tract from the inside out. As a result, the caterpillars stop eating soon after ingestion. After a few days, they die. Sometimes you can see the dead caterpillars hanging under the leaves."

Working method

It is recommended to repeat the application after 7 days, up to a maximum of 6 times per cultivation cycle. The Biobest specialist adds that the efficacy of DELFIN® WG improves in slightly warmer conditions, from 15°.


But it all starts with good monitoring. This can be done with pheromone traps. Many growers now uses the PATS-C detection system. The infrared cameras and software are capable of identifying flying pest insects in real-time within the greenhouse, enabling more accurate and rapid detection. This makes earlier introductions of biological agents possible.

Fast response

"With PATS-C, growers are on top of the moths," continues the specialist. "As a result, they detect the detect the pest up to five weeks earlier than with conventional methods. This enables them to improve the timing of their Bt applications.. A good combination."