Team:KU Leuven/Project

One of man’s basic needs is feeding him/herself. Finding or producing food has always been the primary priority of mankind, of all animals in fact. So as the world’s population expands to over 7 billion but the world’s resources such as land remain limited, the World is in a desperate struggle to increase productivity of the lands already in use 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 then turn to the use of pesticides and insecticides, and society is now questioning whether their ‘fresh’ food isn’t in fact ‘poison’ due to the amount of pesticides that can be detected on their food.

Our goal is to reduce the damage that aphids cause to our agricultural industry in a sustainable way. The current solution is almost always using huge amounts of insecticides, which damage the ecosystem in several ways. First of all, the indiscriminately weakening of insects means that beneficial insects for agriculture are also affected. Insecticides affect vertebrates, including humans, as they have been shown to be damaging for our health (Bjørling-Poulsen et al.). Besides that, residues or catabolites of insecticides accumulate in higher organisms that eat the insects, which in turn end up in our food chain.

We aim to achieve a sustainable way to reduce the damage caused by aphid pests, and offer an effective alternative for insecticides. Our modified E.coli (‘BanAphids’, meaning ‘to ban aphids’ as well as with ‘benefits’) would imitate insecticides by using 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 by using methyl salicylate (MeS), a phytohormone. This way we make sure the aphids are thoroughly removed from the plant.

We have established what might be possible hurdles in introducing this system in the agricultural industry. First we have to make sure that the plant cell’s metabolism is not over burdened. Besides that we have to take into account that aphids might habituate to constitutive expression of EBF (De Vos et al, 2010, Kunert, 2010). Finally, we do not want to attract the aphid’s natural predators when they are not needed.
We thought of two different methods to carry out our system. One method would be to spray our BanAphids onto the plants. Keeping into account the possible hurdles we mentioned before, BanAphids will produce methyl salicylate in response to an external signal that indicates the presence of aphids, in order to reduce the burden on the plant cell’s metabolism and attract predators only when needed. This external signal is honeydew, since aphids produce high amounts of this. Honeydew is a very glucose rich substance, which is the reason why ants ‘farm’ aphids, in order to milk their honeydew.

Figure 1ǀ tet repressor under low glucose promoter.