A New Tool to Help Practitioners in the Integrated Control of a Major Tomato Pest

Tuta absoluta is one of the most destructive pests of solanaceous crops. Agroscope has developed a statistical model to study the population dynamics of the pest and its parasitoids and allows interventions to be optimally planned.

As part of a collaboration between the Agroscope centres of Conthey and Reckenholz and the Institute of Agrifood Research and Technology in Catalonia, the IRTA, researchers have developed a population model to study and forecast the dynamics of the pest and determine the best parameters for releasing the parasitoid in combination with the application of a biopesticide.

Control strategy

One possible biological control strategy consists in augmentative parasitoid releases; however, parasitoid intervention efficacy is highly sensitive to release timing and intensity. Virus-based biopesticides are an additional mean of control, as they are highly selective and can be deployed in combination with biocontrol agents. The conclusions are based on a mathematical model validated with field data.

Evaluation of 4 scenarios

The aim of the study was to assess the best parameters for releasing the parasitoid Necremnus tutae to control the pest in four different management scenarios:

  • With no other control method (as comparative control);
  • in combination with a biopesticide (PhopGV, Baculoviridae);
  • with the natural presence of the parasitoid;
  • combining the natural presence of the parasitoid with a biopesticide.

In addition, two growth seasons of different lengths (7 and 11 months) were modelled and compared in each scenario.

To achieve a satisfactory pest-control level, 3 to 45% fewer parasitoids are needed during a long growing season than during a shorter growing season. Biopesticide applications reduce the number of necessary parasitoids by 66% and 78%, whilst the natural presence of parasitoids reduces the number by 11% and 17% for short and long growing seasons, respectively.

A delayed intervention that remains effective

On average, with the application of the biopesticide, the parasitoid intervention can be delayed by one month and still remain effective.

These results underscore the importance of mathematical modelling in applied parasite control, which allows the establishment of accurate forecasts, crucial for effective control.

Modelling is an important tool for evaluating and improving biological control programmes, as it allows us to forecast the results of different control strategies. Models can help identify the most effective and sustainable approach by simulating interactions between the pests, their natural antagonists and the environment.


  • Applying Baculovirus can reduce the number of required parasitoids by nearly 80%.
  • In addition, fewer parasitoids are needed to achieve control when the growing season is long. This is because the parasitoids have more time to develop a large population to control the pest population.
  • Lastly, the model demonstrated that the timing of the release is crucial for optimising its efficacy, and that the parasitoid can be released later when Baculovirus is applied,
  • On the whole, such models can provide accurate forecasts for practitioners, allowing them to optimise their integrated control strategy with different pest biocontrol agents.
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