Evaluation of Phytoseiid and Iolinid Mites for Biological Control of the Tomato Russet Mite Aculops lycopersici (Acari: Eriophyidae)

The predatory mite Pronematus ubiquitus curbs Aculops lycopersici damage under greenhouse conditions

BACKGROUND

The tomato russet mite, Aculops lycopersici, is a major worldwide pest infesting tomato crops for which only few control methods are available. At present, no commercialized beneficial organism has proven to be an effective biological control agent of the pest. As there is a strong need to develop alternatives to synthetic insecticides, we assessed the efficacy of an iolinid mite, Pronematus ubiquitus, as a preventive method against A. lycopersici in comparison with a curative treatment in a replicated experiment in the greenhouse.

RESULTS

After pre-establishment of P. ubiquitus supplied with cattail pollen, followed by infestation of A. lycopersici, the predator was able to reduce pest populations by 98% as compared with control plants. Probably due to lack of food and high temperature, the number of P. ubiquitus decreased during the season and so the Eriophyid population rose, along with crop damage. The sulphur treatment could stop the progress of A. lycopersici, but their population levels remained high.

CONCLUSION

Pronematus ubiquitus has great potential to prevent the establishment of the tomato russet mite. Even if a curative treatment affects the pest mite, the use of a preventive method is preferable as such insecticides/acaricides are harmful for beneficials and are applied after symptom appearance, when the pest pressure is already high. Despite the need to optimise management of the predator throughout the season, P. ubiquitus proved to be able to establish successfully on tomato plants. © 2023 Society of Chemical Industry.

Modelling the interaction between a pest (Aculops lycopersici), two predators (Pronematus ubiquitus and Macrolophus pygmaeus) and climate variables: a 3-year greenhouse study in a tomato crop

BACKGROUND

The tomato russet mite, Aculops lycopersici, is a major pest in tomato crops, causing damage through leaf and stem browning, defoliation and russeting of fruit. Biological control of this mite on tomato plants is difficult. While several phytoseiid mites feed on the pest, they cannot survive, move, or reproduce on tomato plants due to the presence of glandular trichomes. Pronematus ubiquitus has recently been identified as a biocontrol agent of A. lycopersici in tomato crops, but the predator-prey interaction between these two species is not well studied. In this paper, we present a validated logistic regression predator-prey model based on a 3-year study supplemented with additional datasets. Besides the predator and the prey, this model takes into account an extra generalist predator, Macrolophus pygmaeus, and various climate parameters.

RESULTS

The population trend of A. lycopersici is best explained by the presence of the predator P. ubiquitus, the relative humidity and the fact that the crop was lit or unlit using artificial light. P. ubiquitus has proved to be an efficient biocontrol agent of A. lycopersici. For P. ubiquitus the presence of M. pygmaeus, the vapour pressure deficit, the number of light hours and radiation explained the population trend best. For both the predator and the prey density-dependent interactions were identified. Model outcomes are discussed in detail.

CONCLUSION

Our study provides insights into the potential use of P. ubiquitus as a biocontrol agent for A. lycopersici in tomato crops in combination with M. pygmaeus. However, we highlight the importance of considering the presence of other predators and environmental conditions when developing integrated pest management strategies. © 2023 Society of Chemical Industry.