Team:KU Leuven/Project

One of man’s basic needs is feeding him/herself. Finding or producing food has always been a priority of mankind, of all organisms in fact. While the world’s population expands to over 7 billion resources such as land remain limited, leaving us in a desperate struggle to increase productivity of lands used and encourage innovative agriculture. Weather, disease and pests such as aphids, can reduce crop yields by up to 75% and since weather is difficult to control most farmers try to control the damage caused by disease and pests. Many farmers use pesticides and insecticides, but society has started to question whether their ‘fresh’ food isn’t ‘tainted’ by these pesticides.

Our goal is to create a sustainable system to reduce the damage that aphids cause to our agricultural industry. The current solution usually requires huge amounts of insecticides, damaging ecosystems in several ways. First, the indiscriminate weakening of insects means that beneficial insects (pollinators, ...) are also affected. Second, insecticides affect vertebrates, including humans, damaging our health (Bjørling-Poulsen et al., 2008). Third, insecticide residues (catabolites) accumulate in each food-chain. the highest organism, be it humans or for example predatory birds, will end up with potentially high levels and the negative effects.

We aim to offer an effective and sustainable alternative for insecticides. Our modified E. coli (‘BanAphids’, meaning ‘to ban aphids’ as well as with ‘benefits’) would produce the aphid’s own alarm pheromone, E-β-farnesene, (EBF) to repel them off the plant. On top of that we want to attract aphid predators such as the ladybug via the production of methyl salicylate (MeS), a phytohormone, by our E.coli`s. This way we ensure aphids are thoroughly removed from the plant.

We have established some of the potential hurdles when introducing this system in agriculture. First, the plant’s metabolism should not be overburdened. Second, aphids might habituate to constitutive expression of EBF (De Vos et al., 2010, Kunert et al., 2010). Finally, we do not want to attract the aphid’s natural predators when they are not needed.

We devised two different methods to implement our system. One method would be to spray our BanAphids onto the plants. To minimize the burden on the plant’s metabolism and attract predators only when needed, our BanAphids will only produce MeS when aphids are present. Another way to avoid habituation of the aphids is an oscillating production of EBF, which requires a colony-wide synchronized oscillating system.

Our second method starts from the principle that the BanAphids may not come in direct contact with the plants and the aphids it would carry. To ensure this, we developed our oscillating system such that the BanAphids could alternate between MeS and EBF production without the ``aphid present` signal. We will place our BanAphids in a container, isolated from the environment but producing MeS and EBF in an oscillating pattern, to prevent habituation. We turned to the sticker model of the Groningen 2012 iGEM team to use as a container. The sticker is composed of a plastic film, whose pores are too small for the BanAphids to pass but large enough so the volatile pheromones it produces still pass. The Groningen 2012 iGEM team has already investigated the biosafety of this sticker.

Sticker model

This drawing shows how the sticker could be placed in a rose bush to repel aphids and attract ladybugs.