Effects of aphid endosymbionts on parasitoid biocontrol in greenhouses

Biological control of crop pests is becoming more important with the stricter regulations on pesticide use. Aphids are serious pests in greenhouses, and laboratory studies have shown that parasitoid biocontrol, which is considered particularly effective against aphids, can be seriously affected by defensive symbiosis. In defensive symbiosis, secondary endosymbionts protect its host, the aphid in this case, against natural enemies. Since facultative symbionts have been found in almost all pest aphid species studied so far, this could pose an underestimated threat to biocontrol efficiency. Unfortunately, studies on endosymbiont-conferred resistance in aphids have been limited to the laboratory, with only a few studies on effects in the field. Information on the effects of symbiont-conferred resistance in greenhouses is lacking entirely, and this information is needed for the biocontrol industry. Therefore, during my PhD I study the effects of endosymbiont-conferred resistance on parasitoid augmented biocontrol in Dutch greenhouses.


The aim of this project is to study the dynamics between endosymbionts, aphids and parasitoids in greenhouses, and to use our findings to improve the efficiency of biological control.


During this four-year project, we will sample aphids from a range of bell pepper, cucumber and tomato greenhouses in the Netherlands. We will also sample aphids in the field to look at the occurrence of endosymbionts in field populations. In the lab, we will sequence the aphids and their endosymbionts using barcoding and microsatellites. The second part of the project consists of cage experiments with infected aphids, to look at the effects of the endosymbionts on aphid resistance and to study the variety in parasitoid virulence. During the last phase we will perform large greenhouse-scale experiments to look at the community dynamics between endosymbionts, aphids and parasitoid wasps. This project is in cooperation with Koppert Biological Systems, the world’s leading biocontrol company, and we aim to work together so that our findings can be distributed to the industry and growers, to improve biocontrol success in the most efficient way.

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