The Biology and Integrated Management of Bean Seed Fly.

The aim of the proposed PhD is to increase knowledge about, and understanding of, bean seed fly biology to underpin the development of an integrated strategy for bean seed fly control.  Bean seed fly is a common pest of a range of crops grown in the UK and more widely, including peas, beans, onions and courgettes.  Its effects can be devastating.  Growers, agronomists, seed treatment specialists and researchers believe that there is a need to explore a range of approaches to management and control of bean seed fly since insecticidal options are becoming very limited. 

PGRO and The University of Warwick have collaborated successfully in research projects in the past and are currently collaborating in a project on insecticidal control of bean seed fly funded by the AHDB.  The proposed PhD fits closely with research undertaken within the ‘Plant and Crop Science’ theme in the School of Life Sciences and our emphasis on Integrated Pest Management. It ties in closely with the aims of the Food GRP because vegetables are an important component of a healthy diet and legumes, in particular, may become a more important source of protein in our diet in the future.

1. The PhD will address the following approaches/questions:
   Improved understanding of the bean seed fly life-cycle and the influence of temperature/weather conditions.  This is particularly related to the overwintering stage (what induces it and what ends it). This is to improve our ability to forecast the periods when bean seed flies are laying many eggs and the student will ain to establish a culture of bean seed fly and undertake experimental work in the lab to determine the relationship between fly development and temperature. The student will also monitor bean seed flies and record temperature data in the field to ‘test’ forecasts.  We will aim to determine, using modelling approaches, whether soil day-degrees provide a better forecast than air day-degrees.
   
   
2. Improved understanding of the behaviour and spatial distribution of bean seed fly.  This will involve monitoring flies and sampling for the eggs/larvae at experimental sites and in commercial crops, as well as liaising with growers who are reporting damage to crops.
   
   
3. Approaches to reducing the size of bean seed fly infestations in susceptible crops.  This is likely to be through cultural methods including the timing of cultivations.  Equally important is to understand what increases bean seed fly infestations e.g. cover crops, organic matter in the soil.  This will be field work – either in small plot trials or in collaboration with growers.

Study Summary

"A generalist dipteran pest, bean seed fly causes crop damage when larvae (maggots) feed on germinating and emerging seeds and plants. The worse affected crops in the UK are legumes (such as vining peas) and alliums(salad onions).

The aim of the PhD project is to contribute towards an Integrated Pest Management (IPM)strategy for the fly.

Flies are attracted to lay their eggs in areas of high organic matter. It is thought that the flyis less attracted to lay their eggs near newly sown seeds when cultivation occurs in advance of sowing the crop. We found that damage is reduced on French beans when cultivation occurs at least seven days before sowing. We also found that covering the crop with a fine mesh (0.6mm gaps) on the day of sowing reduces damage, should the grower not be able to delay cultivation.

We tested multiple trapping methodologies. We found that blue sticky traps set up horizontally are selective for the fly. Alternatively, blue sticky traps curled around a lure (sold by Andermatt) were effective at trapping the fly. We also discovered that traps mimicking an increased level of insect cover on the sticky cards were less attractive to the fly. Traps should be left outside for one to two days.

We have realised that bean seed fly has a different over wintering strategy to similar species such as cabbage root fly and onion fly. They seem to have a shorter diapause (similar to hibernation). This means that the methods used to forecast the fly may have to differ from those used to forecast similar species. The forecast is currently in development and will be finished by September 2023."

Sponsors:

Student:

Rebecca McGowan

Start Date: October 2019

Duration of study: 3.5 years