Biological Chemistry

Dr James G Logan

PHD STUDENT PROJECTS:

Control of the common bed bug (PhD student – Emma Weeks)
Bed bug, Cimex lectularius (Cimicidae) infestations are becoming more common particularly in developed countries including the UK.  Bed bugs display aggregation behaviour and this is thought to be caused by the production of an aggregation pheromone. Some anecdotal studies note that they give off a smell like the herb, coriander, Coriandrum sativum (Apiaceae), but to date, the chemicals responsible for the aggregation have not yet been identified.

This investigation aims to identify aggregation semiochemicals and exploit them to develop a new monitoring system for this pest, allowing targeted control and thus minimising the need for conventional toxicant synthetic pesticides. This is a collaborative project with Dr. Mary Cameron of the London School of Hygiene and Tropical Medicine.
 
“Flies and eyes”: developing traps for sampling the trachoma vector (PhD student – Julie Bristow])
Trachoma is the leading cause of preventable blindness world-wide.  It is endemic in the poorest countries with an estimated 6 million blind and 590 million at risk.  The face fly Musca sorbens is a known vector of trachoma and there are indications that volatiles semiochemicals released from the eye region of children, from nasal discharges and human faeces are likely to be strongly attractive to M. sorbens.  Identifying these attractive volatiles, synthesising them, preferably from local sources, and developing chemical traps for M. sorbens would provide much needed surveillance tools for monitoring fly numbers in sites where environmental control programmes are operating for trachoma control. An attractive trap could also be exploited as a method of fly control, if the volatiles were combined with insecticides and/or physical traps.

This investigation, in collaboration with the academic supervisor, Professor Steve Lindsay of the University of Durham, aims to identify new attractants which could be used to develop improved traps for M. sorbens.

Could mosquitoes become “resistant” to repellents? (PhD student – Nina Stanczyk)
Repellents are used worldwide as personal protection against many biting insects including mosquitoes. N-N-Diethyl-m-toluamide (DEET) is one of the most effective and commonly used repellents, however, during laboratory repellency trials a small proportion of mosquitoes still respond to human odours despite the presence of DEET. But can this effect be passed on to successive generations?

Crossing and selection experiments are being performed to establish whether the behavioural differences in response to repellents are based on variation at a single gene or are polygenic, possibly with a threshold effect.  The aim of this project is to understand the potential for mosquitoes to develop ‘resistance’ to repellents; the fundamental genetic basis of attraction of mosquitoes to their hosts and to determine which genes and odourant binding proteins (OBPs) are involved in repellency and attraction by the mosquitoes with the concomitant possibility of using the data in control strategies and understanding  This is a collaborative project with Professor Lin Field of the Insect Molecular Biology Group at Rothamsted and the academic supervisor Professor John Brookfield of the University of Nottingham.

Controlling Culicoides biting midges - (PhD student – James Cook (starting October 2009) )
Culicoides midges are responsible for the transmission of several arboviral pathogens of international importance, including bluetongue virus (BTV) and African horse sickness virus. Since 1998, the distribution of BTV has shifted northwards as a consequence of climate change, culminating in the first cases in recorded history occurring in northern Europe during 2006 and the subsequent spread of the virus to the UK in 2007. While progress has been made in understanding the epidemiology of the virus, several significant areas remain poorly understood, particularly in understanding the role of Culicoides vectors in transmission.

This aim of this project is to provide a fundamental understanding of how Culicoides biting midges locate and select their hosts. This will be employed subsequently in the design of novel tools for surveillance programmes and control and eventual commercialisation.

This is a collaborative project with Dr Simon Carpenter at the Institute of Animal Health, Pirbright and the academic supervisor Professor Stephen Lindsay of the University of Durham.

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