Location
Increasing hoverfly populations in apple orchards for control of apple aphids

Research

TF 218 - Increasing hoverfly populations in apple orchards for control of apple aphids

Start Date: 
01/04/2014
Completion Date: 
31/03/2017
Project Leader: 
Dr Chantelle Jay, East Malling Research
Code: 
TF 218

Industry representative: John Evans, JA Colthup & Partners

 

HDC project cost: £34,088

 

Project summary:

Apple aphids are an ongoing pest problem, and biological control can help to reduce the severity of attack or eliminate the pest problem. Hoverfly larvae are voracious predators of aphids and if adults can be attracted into the orchard early in the season, and/or encouraged to overwinter in or close to orchards, this increase in predators would be an important component of an IPM strategy. Hoverflies overwinter either as adults or pupae depending on the species. Biocontrol is particularly effective where ants are discouraged from protecting the aphids. Hoverfly adults respond to plant produced volatiles and to components specific to aphid feeding. Therefore, dispensers containing synthesised plant volatiles will be assessed in replicated field experiments in apple orchards to assess the potential attractiveness of these chemicals to hoverflies. If successful these will be combined with visual cues which are also known to attract hoverflies.

 

Aims and objectives:

(i) Project aim(s):
The overall aim will be to increase hoverfly populations in apple orchards as predators of aphids
 
(ii) Project objective(s):
1) To determine whether populations of hoverfly species can be increased in orchards in the spring
2) To determine whether increasing populations of adult hoverflies in the autumn will lead to increases in hoverfly populations in the orchard in the spring
3) To determine the degree to which increases in hoverfly populations reduce aphid populations in the orchard
 
 
Benefits to industry:
 
Apple trees are subject to a number of aphid pests including the rosy apple aphid (Dysaphis plantaginea (Passerini)), the rosy leaf curling aphid (Dysaphis devecta (Walker)) and the green apple aphid, (Aphis pomi (De Geer)). When conditions are favourable pest numbers can increase rapidly. The rosy apple aphid is the most damaging of these and high numbers result in curled leaves and misshapen fruits, which can lead to economic losses. The threshold for Assured Product for RAA quotes that pesticide application is justified if one aphid is found in the orchard pre-blossom. Some organic orchards in 2013 have seen 100% crop loss from rosy apple aphid.
• Integrated pest management (IPM) strategies reduce pesticide inputs, residues on the fruit and the risk of development of pest resistance to products
• The use of plant volatiles to attract beneficial species is compatible with IPM and organic control programmes in apple orchards
• If successful we will be able to manipulate beneficial species numbers in orchards with the aim of ultimately reducing pest numbers
• Attraction of hoverflies into orchards would also be economically favourable as they are important pollinators and are reported to be the most important pollinator group after wild bees.