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Field and laboratory studies of Bacillus thuringiensis populations: the dynamics of diversity and its consequences for the evolution of resistance

Reference	BB/C512702/1
Principal Investigator / Supervisor	Dr Michael Bonsall
Co-Investigators / Co-Supervisors	Dr Benjamin Raymond, Professor Denis Wright
Institution	University of Oxford
Department	Zoology
Funding type	Research
Value (£)	303,270
Status	Completed
Type	Research Grant
Start date	01/03/2005
End date	31/12/2008
Duration	46 months

Abstract

Bacillus thuringiensis (Bt) insecticides and genetically modified plants (that include the endotoxins (Cry toxin) genes) can provide safe and effective methods for insect pest control. However, concomitant with these technological developments, is the increased possibility that the insect pests show resistance to the use of Bt. While resistance management strategies adopted from the outset have proved successful in preventing an increased frequency of resistant alleles in populations of pests such as Heliothis virescens, Helicoverpa zea and Pectinophora gossypiella on cotton and Ostrinia nubialis on maize, the risk of significant levels of resistance developing remains, particularly if the use of Bt continues. Several insect species have been selected for resistance to the Cry toxins in the laboratory but only two, the diamondback moth, Plutella xylostella and the cabbage looper moth, Trichoplusia ni, have been reported to have developed resistance in the field. For studying resistance. Plutella xylostella is the better system since resistance to the Cry 1 toxins is far more widespread, having been selected by intensive Bt spraying on brassica crops in Asia and the Americas since 1980s. While development of Bt technologies is relatively well supported, one unexplored and important aspect of Bt in integrated pest management is the diversity of the Bt bacteria and the consequences this has for agroecosystems. In particular, we are interested in what are the effects of Bt applications on the diversity of dynamics of native Bt (and related B. cereus) morphotypes? Does Bt persist in the soil and or on plants? What possibility is there that Bt in natural populations is sufficient to exert selection pressure for the evolution of resistance genes? These are key questions in resistance management and theory. This study is unique in that it will develop these themes by suing a multidisciplinary approach. Designed field and laboratory studies will be implemented to explore a series of key objectives on the dynamics and diversity of Bt on the evolution of resistance in diamondback moth. Complimentary to these, a series of mathematical models will be used to explore how the dynamics and diversity of Bt affect the evolution of resistance. Developing this research programme will allow an understanding of how Bt dynamics affect pest populations in a worldwide insect pest. These results will be beneficial in the development and implementation of future control measures for similar insect pests, including those in the UK.

Summary

unavailable

Committee	Closed Committee - Agri-food (AF)
Research Topics	Crop Science, Microbiology, Plant Science
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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