Macrolophus pygmaeus as a key aphid control agent in sweet pepper: efficacy and intraguild interactions

Abstract: Aphid management in sweet pepper crops in Belgium typically relies on complex
biological control strategies involving multiple predators and parasitoids. While these multispecies approaches can be effective, they are often costly and may result in intraguild
interactions that reduce overall control efficacy. Previous experiments have shown that
Macrolophus pygmaeus, when well established, is capable of controlling aphid populations in sweet pepper crops without the need for additional biological control agents. However,
insufficient establishment of M. pygmaeus can lead to inadequate aphid suppression and relying on one key predator might hold more risk.
This study evaluated the role of M. pygmaeus in aphid control in sweet pepper, with a
specific focus on intraguild predation and the added value of complementary natural enemies. Interactions between M. pygmaeus and commonly applied aphid control agents, including  Aphidius spp., Aphidoletes aphidimyza and Propylea spp., were assessed in walk-in insect cages  under greenhouse conditions. In addition, the effectiveness of aphid control by M. pygmaeus alone was compared with strategies combining M. pygmaeus with parasitoids or specialist predators.
The results provide insight into how intraguild interactions influence the performance of
biological control agents and overall aphid suppression. These findings support the
development of more cost-effective and simplified biological control strategies in sweet pepper by clarifying when M. pygmaeus alone can ensure reliable aphid control and when additional natural enemies may offer added value. Further research is needed to analyze the risk of relying on a single species for inoculative biocontrol. Would the potential cost savings not be offset by the need for inundative releases of other control agents in case of failure?