Improving aphid biological control with the predator Aphidoletes aphidimyza

Biological control, either alone or as part of Integrated Pest Management (IPM), is an efficient and environmentally friendly method for pest control. Especially in Europe, biological control is increasingly important due to the new Regulation on the Sustainable Use of Plant Protection Products, including targets to reduce by 50% the use and risk of chemical pesticides by 2030. Augmentative biological control of arthropods by arthropods is based on the mass-production and release of natural enemies, i.e., predators and parasitoids, to manage the pest populations. The way the natural enemies are packed and released in the field may have a crucial impact on their quality and eventually the biocontrol services they can provide. Therefore, optimising the packaging formulations of natural enemies is a means of substantially enhancing their fitness and in turn their potential for pest control. The predatory gall midge Aphidoletes aphidimyza (Diptera: Cecidomyiidae), is one of the most important predators employed in the augmentative biocontrol of aphids worldwide. It is supplied to end-users as pupae mixed with sawdust in plastic units. We performed several experiments testing a new packaging for A. aphidimyza with the objectives of i) replacing the plastic unit with a sustainable alternative while at the same time ii) maintaining or even enhancing the performance of the predator. A new packaging prototype made of cardboard that is 100% biodegradable was tested. In several experiments performed under laboratory and greenhouse conditions, we found that the percentage of A. aphidimyza pupae hatching and eventually the number of adults flying out was consistently higher in the new prototype unit compared with the current packaging. Addition of a gel or directly adding water to increase the moisture content of the sawdust in the prototype did not improve the number of adults flying out. In conclusion, the new prototype packaging tested improves the sustainability aspect as well as the performance of A. aphidimyza.