As part of the Kas als Energiebron pilot program, a pilot was conducted in two experimental greenhouses at Vertify in 2024 with cocktail tomatoes of the Annico Cove cultivar. The demonstration focused on the use of the predatory bug Macrolophus pygmaeus, the predatory mite Pronematus ubiquitus, the monitoring system PATS-C, and two species of parasitic wasps Trichogramma brassicae and Trichogramma achaeae.
One of the aims was to demonstrate, in collaboration with Biobest, the effect of the predatory mite Pronematus on the tomato rust mite Aculops lycopersici. At the same time, in cooperation with Pats and Bioline, the PATS-C camera system and the effect of a mix of two Trichogramma species on the eggs of the Tomato looper (Chrysodeixis chalcites) were demonstrated. Pats-C systems were installed in both greenhouses and Pronematus and the two species of Trichogramma parasitic wasps were released. The demonstration was carried out both with and without the presence of Macrolophus.
No spraying against pests
To avoid disruption of the demonstration, various natural enemies were deployed against spider mites, whiteflies, leafminers, and aphids. Against whiteflies, a mix of Encarsia formosa and Eretmocerus eremicus was introduced (weekly, 2 to 37 per week). For spider mite control, the predatory mite Phytoseiulus persimilis was used almost weekly (10 to 100 per week) and, especially in May, the gall midge Feltiella acarisuga (a total of 22 per m2).
Aphids were intensively controlled from May to early July with about 90 gall midges Aphidoletes aphidimyza per m2, 30 parasitic wasps Aphidius ervi and 20 Aphidius colemani per m2, and 3 Propylea per m2.
Leafminers were sporadically found and controlled with the parasitic wasp Diglyphus isaea (5/m2).
This intensive approach meant there was no need to use chemical plant protection products during cultivation, with the exception of mildew control.
Pronematus against tomato gall mites
At the beginning of cultivation and in September, after spraying against mildew, the predatory mite Pronematus ubiquitus was released with 100 and 50 specimens per stem, respectively. This was done with the help of iris pollen (Typha angustifolia), to promote the establishment of the predatory mite.
Special attention was paid to leaf picking to avoid disturbing the development of the predatory mite by leaf removal. Vertify was instructed to keep a minimum of 16 leaves per plant. Pronematus was established immediately after the first round of introduction. However, numbers were affected by sprays against powdery mildew. Nevertheless, the predatory mites achieved a maximum density of 20 predatory mites per leaf, with an average of 2 predatory mites per leaf throughout the cultivation period. In July, some plants in both greenhouses were infected with tomato rust mites.
The accumulated population of Pronematus was able to control Aculops infections until the end of the crop. Damage was limited to the last two weeks of October: only 10 leaves (in the entire greenhouse) showed any infestation.
Predatory bug Macrolophus pygmaeus against various pests
The predatory bug Macrolophus was introduced once in one of the two greenhouses on 5 March, at a dosage of 2.5 specimens per m². Upon introduction, 500 g of standard brine shrimp cysts (Artemia) per hectare were spread over the crop. The supplementary feeding was then repeated weekly for five weeks.
Macrolophus quickly established itself: in May, they were already counting more than one predatory bug per leaf, and in July this number rose to two per leaf. In late June, Macrolophus was also found in the greenhouse where it had not been introduced.
The added value of the predatory bug was clearly visible until week 30. After that, Macrolophus was well established in both greenhouses. Macrolophus was effective against whiteflies, spider mites, and aphids. The number of whiteflies was reduced by a factor of 4 to 5. Moreover, they found three times fewer spider mites in the greenhouse and hardly any aphids in the greenhouse with Macrolophus.
When aphids (a mix of potato aphid and peach aphid) were first found in the greenhouse without predatory bugs, additional natural enemies such as ichneumon wasps, ladybirds, and gall midges were released in both greenhouses. Nevertheless, an average of 27 aphid hot spots were counted between 15 May and 11 June In the greenhouse without Macrolophus, while the greenhouse with Macrolophus remained virtually aphid-free.
Mildew was also less prevalent in the greenhouse with Macrolophus, although this may be explained by differences in the number of wet spots between the two greenhouses.
Trichogramma parasitic wasps against caterpillars
From 6 February, 10 dispensers with a mix of Trichogramma parasitic wasps were deployed every fortnight in both greenhouses. A combination of the species Trichogramma achaeae and Trichogramma brassicae was chosen for the 'Tomato without sulphur' project. The deployment of the Trichogramma parasitic wasps was 250 per m2.
Despite the introductions of the moths, only a few caterpillars were observed in the crop without causing any damage. Besides the intensive observations in the crop, the PATS-C camera system provided very good support in the detection of flying moths. This not only indicated the success of the introduction but also provided insight into the development of the pest.
Funding
The program was financed 50% by the practical program Plant Health and the Kennis in je Kas (KIJK) foundation and 50% by the Tomato Crop Cooperative. In addition, the parties involved (Biobest, Bioline, and Pats) contributed in kind by introducing biological control agents, carrying out monitoring, and reporting. Vertify was responsible for cultivation.
Source: Kennis in je Kas