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Spatial dynamics and predictive modelling of large narcissus fly (Merodon equestris) populations - HH1747TBU

The research proposed in this study, which develops the findings of previous research on large narcissus biology and control funded by MAFF and the HDC, has two main objectives: (1) to determine the main spatial factors to affect adult large narcissus fly host-selection and egg-laying behaviour on a field scale, (and establish principles for the manipulation of pest spatial distribution in commercial crops). (2) to determine and model the influence of weather conditions and bulb physiology on pest survival and multiplication.

Large scale experiments in commercial narcissus crops, and semi-field cage experiments, will investigate the influence, both of selective crop defoliation, and of the distribution and abundance of adult food sources on adult fly dispersal and egg-laying preference behaviour under field conditions, and will determine ways in which pest spatial distribution might be influenced by manipulation of these factors. Data will be collected on stage-specific pest mortality in relation to weather conditions and bulb physiology, and used to adapt the existing large narcissus fly phenology model so that it can be used for quantitative risk assessment. Field data will be collected from commercial crops and used to test the accuracy and robustness of the model’s predictions.

If successful, this underpinning study would make possible the replacement of the relatively ineffective and environmentally undesirable chemical control measures currently used for large narcissus fly control in the UK, and would thus contribute critically to the future health of UK narcissus bulb stocks, and hence to the competitiveness of the UK narcissus industry.

1. To re-stock and build up field and insectory cultures at Starcross and Wellesbourne (2001/2, 2002/3 & 2003/4)

2. To collect field data on poulation density in commercial crops for retrospective model validation (2001/2, 2002/3 & 2003/4)

3. To find a suitable commercial site for the field-scale spatial dynamics experiments on host-plant selection (2001/2 & 2002/3)

4. To investigate the effect of partial crop defoliation on the spatial dynamics of host-plant selection (2002/3)

5. To investigate the effect of adult food-plant type, abundance and distribution on the spatial dynamics of host-plant selection (2003/4)

6. To investigate the relationship between environmental conditions and mortality of first-instar and second-instar larvae imimmediately before and after bulb invasion (2001/2 & 2002/3)

7. To add mortality functions to the existing phenology model (2002/3)

8. To validate the upgraded model retrospectively against commercial crop data collected each year (2002/3 & 2003/4)
Project Documents
• Final Report : Spatial dynamics and predictive modelling of large narcissus fly (Merodon equestris) populations   (159k)
Time-Scale and Cost
From: 2001

To: 2004

Cost: £152,300
Contractor / Funded Organisations
Pest Control              
Fields of Study