EV2LARCK

3229

24 décembre 2020 10:46

12 avril 2021 16:07

Biological pest management is already quite successful in European sweet pepper greenhouses and many major pests can be controlled by augmentative releases of natural enemies. Aphids are a major pest for which the currently used specialist natural enemies don’t provide sufficient control and chemical interventions are often applied. Organic growers can’t use synthetic insecticides and the number of effective insecticides allowed in organic farming is very limited, therefore they occasionally suffer from severe aphid infestations. Due to their high reproductive rate and short generation time, aphids are able to quickly develop insecticide resistance. Increased attention to the role of generalist natural enemies, which attack different types of prey in contrast to specialists, in pest control has caused researchers to look more towards generalist predatory bugs to control aphids and other pests. Macrolophus pygmaeus is one of these predatory bugs with potential. They are commonly used in European tomato greenhouses against a number of pest species such as whiteflies, aphids, thrips, mites and caterpillars. This PhD research focuses on extending the use of M. pygmaeus to sweet pepper cultivation, with experiments under conditions that resemble commercial practice. First of all, release strategies of M. pygmaeus in sweet pepper were tested with regard to food supplementation. Not all generalist natural enemies require food supplementation and different food types or supplementation strategies can affect population growth and dispersal in the crop. Supplementing food had a large positive effect and brine shrimp (Artemia spp.) cysts proved to be the best food source for this. A biweekly supplementation in a full field fashion was found to be the best strategy. After figuring out how best to establish an M. pygmaeus population in the greenhouse, its potential as biological control agent against two sweet pepper key pests, namely aphids and thrips, was studied. The effect of M. pygmaeus on aphid control was combined with leaf pruning at four different heights in order to decrease the vertical foliage length and bring pest and predator closer together. The predatory bugs were found to successfully control aphid infestations in sweet pepper if vertical foliage length of the plants was kept no longer than 190cm. Western flower thrips Frankliniella occidentalis is currently managed in sweet pepper by releasing the predatory bug Orius laevigatus. However, M. pygmaeus also feeds on thrips and may dismiss the need for O. laevigatus releases. During the three seasons of experiments for this PhD, M. pygmaeus was always able to control thrips outbreaks on its own. In the last part of this PhD, collected times series data of thrips and M. pygmaeus population densities were used to construct predator-prey models that could predict pest control. The fitted logistic regression model was able to predict the chance of pest control one week into the future. We developed a strategy to release M. pygmaeus in sweet pepper greenhouse where it can control thrips and aphids, though the latter requires some extra work in the form of leaf pruning. Both pests could be successfully controlled without the need for other natural enemy releases or chemical interventions. The developed population model predicts chance of thrips control and can help growers who monitor pest and natural enemy populations in their greenhouse to make better decisions on pest management measures. Together, these findings can bring growers a step closer to pesticide-poor or even pesticide-free sweet pepper cultivation.

None

• AB - Utile à l'AB
• FREDO lutte
• GEO Belgique
• GEO Europe
• GEO Flandre
• biocontrol
• insect pests

2020

1 janvier 2020