In Northern Europe, the predatory bug Nesidiocoris tenuis, commonly referred to as Nesi, presents a growing challenge for tomato growers. While the species is deliberately deployed as a biological control agent in Southern Europe, where it targets pests such as whitefly and Tuta absoluta, it can also develop into a damaging pest in its own right under northern growing conditions.

At high population densities, Nesidiocoris can cause significant crop damage in tomatoes, including necrotic rings, damage to growing points, and flower drop. Early detection and accurate population monitoring are therefore essential to limit economic losses.

More focus on early detection
Attention to early-stage monitoring of Nesidiocoris has increased considerably in recent years. Growers want to identify the presence of Nesi in their crops before damage becomes visible, rather than responding after the fact. Effective monitoring tools help track population development and allow timely, targeted intervention.

PheroNesi as a tool for targeted monitoring
Dutch crop protection company HortiPro has developed PheroNesi, a pheromone product designed to support the detection and monitoring of Nesidiocoris tenuis. The product is intended for use in combination with yellow sticky traps and helps make Nesi populations more visible in the crop.

PheroNesi has been trialled with growers in the Netherlands and in other countries. According to Thomas de Leijer, commercial technical advisor at HortiPro: "The results show that the pheromone can make a valuable contribution to more reliable monitoring of Nesidiocoris populations."

Field results show clear added value
Trials comparing yellow sticky traps with and without PheroNesi have shown a clear difference in catch rates. In trials using 20 traps with pheromone alongside 20 traps without, the number of Nesidiocoris caught on pheromone-baited traps was substantially higher, in some cases by as much as 160%.

A notable secondary finding concerned Macrolophus, another predatory bug widely used as a beneficial insect in greenhouse crops. Traps equipped with a PheroNesi dispenser caught on average 37% fewer Macrolophus than unbaited traps. This selectivity may be a practical advantage in crops where Macrolophus is part of the integrated pest management programme.

HortiPro has also observed international interest in the product. According to De Leijer: "In France in particular, where Nesidiocoris tenuis tends to pose a greater challenge in tomato production than in the Netherlands, the pheromone has been well received. PheroNesi therefore offers potential for growers across multiple countries dealing with Nesidiocoris pressure."

Optimal use of PheroNesi
Correct application of the pheromone is important for reliable performance. The following guidelines apply:

• In summer, the pheromone lasts 4-6 weeks, while in winter its lifespan is 6-8 weeks. Replace the pheromone dispensers after this period.
• Use yellow sticky traps (with a 14 mm hole) with dry glue. Nesi sticks to these better.
• Replace the yellow sticky traps if they become heavily contaminated.
• Hang the dispensers in the greenhouse as soon as possible after receipt. If immediate installation is not possible, store them in the refrigerator to prevent premature evaporation of the pheromones.
• Hang the yellow sticky traps with the pheromone no more than 30 cm above the top of the crop. They can be attached to yellow roller traps with a stapler or with magnetic hooks to the greenhouse posts if roller traps are not available.

Advice for detection and monitoring
For standard signalling and monitoring of Nesidiocoris tenuis, HortiPro advises placing 10 to 20 pheromone-baited yellow sticky traps per hectare.

When pest pressure is elevated, more intensive monitoring is recommended, with more than 100 pheromone-baited traps per hectare.

To evaluate the system's performance under their own growing conditions, growers can run pheromone-baited and unbaited traps side by side. A clearly higher catch of Nesidiocoris on the pheromone traps confirms that PheroNesi is functioning effectively in that particular crop environment.

Source - https://www.hortidaily.com