Mosquitoes are major carriers of human diseases, including Zika virus, malaria and west Nile fever. There are not many safe insecticides available to kill mosquitoes that are not damaging to the environment or human health. One of the few available is Bin toxin, which is made by a particular type of bacteria called Lysinibacillus sphaericus, which kills mosquito larvae. However, mosquitoes are developing resistance to the toxin. It is vital that we find out how Bin toxin kills mosquitoes so that it can be made more effective or that alternatives can be identified. Not much is known about how Bin toxin kills mosquitoes. We know it binds to a particular protein in the gut of mosquito larvae. Binding of the toxin to this protein causes changes in the cells in the mosquito gut - the toxin is taken into cells of the gut causing large bubbles to form inside them and somehow this leads to death of cells in the gut and then death of the mosquito. Bin toxin has two parts, BinA and BinB, it is BinB that binds to the protein in the mosquito gut but both parts are needed to kill mosquitoes. Both BinA and BinB are part of a family of toxins called Toxin_10. This toxin family are similar in certain ways to proteins that bind sugars, especially sugars which are attached to lipids (fats). Several toxins are already known to us that use their ability to bind (stick to) these sugar modified fats in order to gain entry into cels and then kill their target cells once they are inside. These include the toxins involved in cholera and tetanus. We have evidence that Bin toxin also binds to one of these sugar modified fats, which we call "glycolipids", but we don't know which one yet. We aim to discover exactly which glycolipid Bin toxin binds to, and whether this is important for Bin toxin to be able to cause bubble formation inside cells and kill mosquitoes. We will also discover which exact parts of the Bin toxin proteins are responsible for binding the glycolipid, and whether making alterations in these areas changes the ability of Bin toxin to bind glycolipid or kill mosquitoes, which may help make a more effective insecticide. Other members of the Toxin_10 family that Bin toxin belongs to kill different insects, several of which are economically important agricultural pests. Resistance to current pesticides is also a major problem in agriculture, and there is a pressing need for alternative methods to control these pests. One of these Toxin_10 family members is Cry35, which kills the Western corn root worm, a major problem in maize production in the USA. We will investigate whether Cry35, like Bin toxin, also binds a glycolipid and, if it does, whether this is important for its ability to kill Western corn root worm. This research has the potential to find out how Toxin_10 toxins are killing insects. With this information, we may be able to make them more effective pesticides, thus reducing the spread of mosquito-borne disease and agricultural reliance on chemical pesticides.

Phytoplasmas are intracellular bacterial pathogens of plants that are transmitted by insect vectors. They induce a variety of symptoms in plants and crops, such as witches' brooms (increased lateral branching) and phyllody (flowers reverting into leaves that remain sterile). Phytoplasmas can negatively impact crop production in many regions of the world. They interfere with flower production and decline fruit/grain yields, a problem in maize, fruit trees, grapevines, coconut etc. Because phytoplasmas are insect-transmitted, their occurrence is expanding as the climate warms up and pesticide use is being restricted. The Hogenhout (SH) group at The John Innes Centre has made significant progress with phytoplasma pathogenesis and their impact on host plants. This group found that phytoplasmas produce specific virulence proteins (effectors), which interact with conserved plant proteins leading to crinkled leaves, increased lateral branching (witches' brooms) and the downregulation of plant defence responses to the phytoplasma insect vectors. The latter leads to a greater number of insect vectors that transmit the phytoplasma to other plants. So far, the SH group has focused on phytoplasma interactions with the model plant Arabidopsis thaliana. In this project, the SH group will collaborate with the Spotti-Lopes (JSL) group at The University of Sao Paulo in Brazil who has studied the ecology and epidemiology of an important phytoplasma disease agent of maize. This pathogen causes maize bushy stunt disease and is transmitted by the corn leafhopper, which builds up to high population levels in maize fields in Brazil, Argentina and Mexico, therefore triggering severe phytoplasma epidemics. Maize bushy stunt phytoplasma and the corn leafhopper have co-evolved with the domestication of maize from its wild progenitor, teosinte, and hence are well adapted to colonize maize. Phytoplasma-infected maize plants typically produce more primary and secondary lateral branches (hence, the name maize bushy stunt phytoplasma), fewer ears and lower grain yields. These infected plants may support a greater number of corn leafhoppers that transmit maize bushy stunt phytoplasma to other maize plants. Together the SH and JSL group will translate the knowledge from the phytoplasma-Arabidopsis system to investigate maize bushy stunt phytoplasma and the corn leafhopper in maize. More specifically, we will determine if a maize bushy stunt phytoplasma effector protein induces the increased branching and reduced grain yield symptoms typically observed in phytoplasma-infected maize. Moreover, we will determine of this effector suppresses plant immunity to the corn leafhopper leading to greater leafhopper populations. We will also investigate the genomic variation of maize bushy stunt phytoplasmas in Brazil. Finally, we will assess if we can generate maize varieties that are not targeted by the phytoplasma effector protein leading to a reduction in maize bushy stunt symptoms and increased grain production during phytoplasma epidemics. We will collaborate with the agricultural company Dow Agrosciences. This project will provide exchange visits and a learning platform for all staff involved. Overall this work will increase our fundamental understanding of how pathogen virulence factors (effectors) adapt to host targets thereby facilitating pathogen colonization of these hosts and pathogen dispersal by insect vectors.

Globally, glyphosate use has increased very significantly since the introduction and widespread adoption of genetically-modified (GM) glyphosate-resistant crops. In the UK, these crops are not currently grown, yet glyphosate use in agricultural situations has increased substantially in recent years as resistance to other herbicides has proliferated and reduced soil cultivation systems have been adopted. Evolved resistance following repeated use of glyphosate has now been reported in 19 weed species across six continents, including in France, Italy and Spain. To date, no evolved resistance to glyphosate has been reported in UK weed species. In the past, the majority of herbicide resistance research has been reactive - suspected resistance to a herbicide is reported and efforts are made to confirm and characterise the resistance trait after the fact. A number of converging factors including increasing glyphosate use, the potential future introduction of GM glyphosate-resistant crops to the UK, reports of glyphosate resistance in other European countries and changes to EU pesticide legislation make it timely to ask - what are the future risks of glyphosate resistance evolution in major UK weeds? The project will commence with a UK-wide collection of seed populations of major UK weeds with known and contrasting glyphosate use histories. The project will likely focus on Alopecurus myosuroides (black-grass), though other weeds will also be included. A series of glasshouse-based glyphosate dose response assays will be performed to determine the glyphosate sensitivity of collected populations and to relate this sensitivity to glyphosate use histories. It is not expected that high levels of glyphosate resistance will be detected in populations. However, the project will test the hypothesis (supported by previous research by the main supervisor) that gradual reductions in the sensitivity of populations, related to past use histories, are a precursor to major phenotypic resistance (failure of commercial herbicide applications). This phenomenon, sometimes referred to as 'creeping resistance' has often been speculated on, though never unequivocally demonstrated and offers the intriguing and practically significant possibility of an early warning system for glyphosate resistance. In order to further test this hypothesis, black-grass populations showing evidence of reduced sensitivity to glyphosate will be chosen for glasshouse-based selection experiments. These experiments will expose populations to recurrent multi-generational selection with commercially-applied doses of glyphosate to determine if it is possible to select for major phenotypic resistance. These experiments will provide 'proof of principle' for the early warning system for glyphosate resistance. Where it has been possible to select for resistance, appropriate molecular genetic and physiological techniques will be used to determine the mechanism of resistance. Glyphosate dose response and plant growth analyses will also be performed on evolved resistant populations to determine the fitness consequences of evolved resistance in the presence and absence of glyphosate. Based on the knowledge and understanding gained from these empirical studies, existing population-based simulation models of herbicide resistance evolution will be modified to explore the risks associated with current and likely future glyphosate use in the UK. Management strategies to mitigate these risks will be evaluated using computer simulation and recommendations will be made for proactive management to reduce the likely future incidence of glyphosate resistance in the UK.