I am currently studying for a PhD at the University of York and Stockbridge Technology Centre. My supervisors are Dr Peter Mayhew and Dr Pat Croft.

Links to useful organisations and societies

• Biological control and Integrated Pest Management
• Horticultural and agricultural entomology
• Sustainable resource management
• The relationship between behavioural ecology, life history theory and population biology
• Insect husbandry for experimental and commercial purposes

The aim:

I am studying  the biology and ecology of S. tenuicosta and its parasitoid natural enemies A. debilitata and K. psiloides. I  am assessing the potential of both parasitoid species to control shore fly in commercial horticultural situations.

My work involves a combination of laboratory experiments at a behavioural and life history level , and glasshouse trials at a population  level. The laboratory experiments involve assessment of key biological characteristics of all three species which relate to prediction of control potential (e.g. fecundity, longevity, sex ratio and search efficiency). The population level trials then test the validity and reliability of these predictions.

The problem:

Glasshouse shore flies are small, robust flies of the Scatella stagnalis group (Diptera: Ephydridae). Shore flies are a common nuisance pest in protected horticultural crops such as lettuce, celery, potted herbs and ornamentals. Where large populations of Scatella tenuicosta develop, they can contaminate some of the crops with faecal spotting (frass) and large numbers of larvae and adults may also be harvested along with the crops, these two factors can lead to whole batches of crops being rejected by retailers or consumers. Therefore, despite not causing direct damage to crops, the presence of large shore fly populations can still vastly reduce crop marketability.

The pest:

• Scatella tenuicosta Collin is probably a holarctic species and is distributed over North America, Eurasia and North Africa
• Shore fly naturally occur on the coast and around lakes and pools, where they feed on green algae and other microorganisms
• In glasshouses, algal development on the surface of growth media and in standing water is common. Shore fly larvae and adults a feed on these algae.
• The life-cycle consists of an egg, three larval instars, a pupal instar and the adult
• The larvae are semi-aquatic and are found in the top layer of damp soil or around the edges of standing water contaminated with algae.
• The larvae are a maximum of 8mm with no obvious head. The first instar is white transparent turning to brown opaque by the third larval instar.
• The adult flies are a maximum of 6mm, black with short legs and antennae. The wings are distinctively spotty.

Control of shore flies to date:

Biological control efforts to date have had little impact on shore fly populations. Entomopathogenic nematodes Steinernema feltiae and S. carpocapsae, the predatory mite Hypoaspis miles and entomopathogens Bacillus thuringiensis and Paecilomyces fumosoroseus, have all shown limited success (Vänninen & Koskula, 2003; Jacobson et al., 1999). Growers have had to adapt their cultural practices and use broad-spectrum algicides to reduce numbers. However, these measures are rarely sufficient, and the increasing pressure on growers to reduce pesticide applications to their crops means there is a need to establish suitable biocontrol agents to control shore fly as part of an Integrated Pest Management programme.

The solution?:

It has recently been observed that the presence of two parasitic wasp species, Aphaereta debilitata (Braconidae: Alysiinae) and Kleidotoma psiloides (Figitidae: Eucoilinae), appeared to give good natural control of shore flies. Both these species are solitary, endoparasitic koinobionts, meaning that they develop within their host and allow it to continue developing until they emerge and kill it. There has only been a small amount of research on these species and I am studying their biology and behaviour in order to assess their potential contribution to a successful biocontrol programme for shore flies.



                  

References:

Jacobson, R.J. Croft, P. & Fenlon, J. (1999) Scatella stagnalis Fallén (Diptera: Ephydridae): Towards IPM in protected lettuce crops. IOBC/WRPS Bulletin 22(1) 117-120

Vanninen, I. & Koskula, H. (2003) Biological control of shore fly (Scatella tenuicosta) with steinernematid nematodes and Bacillus thuringiensis var. thuringiensis in peat and rockwool. Biocontrol Science and Technology 13, 47 – 63