Why use Spotted Wing Drosophila (SWD) monitoring traps?

Why use Spotted Wing Drosophila (SWD) monitoring traps?

Spotted Wing Drosophila (Drosophila suzukii, SWD) is a fly pest of a numerous soft and stone fruits grown in the UK. Crops under threat include strawberries, raspberries, blueberries, cherries and grapes. Since its first detection in the UK in 2012, SWD has been spreading across the country. Use of monitoring traps is an essential part of all Integrated Pest Management (IPM) programs against this pest. DrosalPro traps filled with DrosaLure attractant allow detection of the pest, an understanding of risk posed to the crop, identification of over wintering sites and sources of infestation. There is no one product that will completely manage SWD, no silver bullet, pest monitoring is one important tool for soft and stone fruit growers.

  • Monitoring to identify pest population activity
  • Precision monitoring around crop boundaries to identify sources of infestation
  • Integrates into every growing system and with every other tool used to manage SWD


What is Spotted Wing Drosophila (SWD)?

Spotted Wing Drosophila (Drosophila suzukii, SWD) is a fruit fly pest first discovered in the UK (Kent) in 2012. This species was originally from South-East Asia but, with global trade, in recent years has spread to major fruit growing markets around the world. It is a pest to UK soft and stone fruit production because, unlike many other flies, females are able to lay eggs within green unripe fruit. It is a pest of a range of fruits including strawberries, raspberries, blueberries, currants, grapevines, cherries and plums.

Spotted Wing Drosophila flies can be distinguished from many other flies by their size (3-4 mm in length), yellow body and red eyes. Males can be differentiated from closely related species by the single black spot on each of its wings. Females have no black spot but do have a serrated, chainsaw like, ovipositor which can often clearly be seen after being caught in a cup trap.


What are Drosal Pro traps?

Drosal Pro is a refillable and reusable cup trap. It can be emptied and refilled through a season and used for multiple years. Dorsal Pro are versatile traps, easy to handle and its built-in hook allows easy attachment to the crop, growing structure or fence. Their small size makes them ideal to be placed at high density, for example as field perimeter precision monitoring. The trap entry holes have been specifically designed to allow SWD to enter but exclude larger flies meaning a higher proportion of trapped flies are SWD so reducing the time required to count a sample. The smaller size of the trap also reduces evaporation of the liquid attractant therefore removing the need for additional refilling during hot weather. 

  • Refillable cup trap, easy to open and check for trapped SWD
  • Suitable for use with any liquid attractant
  • Combined visual attraction of SWD flies to black lid and red liquid bait
  • Reduced labour requirement for counting – engineered to catch SWD
  • Reduced labour with less frequent refilling – lower evaporation of bait


What is DrosaLure liquid attractant?

DrosaLure is a red coloured liquid bait for use in SWD traps. Made from natural ingredients it attracts both male and female flies. Adult D. suzukii are attracted to both the fruit scent released from the bait as well as the dark red appearance. This liquid attractant can be used in any SWD trap. Packaged in easy to handle HDPE bottles with an easy to pour top of bottle handle and a wide pouring hole for regular flow.

  • Attracts both male and female SWD
  • Suitable for use with any SWD trap
  • Attractant is made from food grade material
  • 1 bottle of 5 L DrosaLure fills approximately 66 Drosal Pro traps


How to use SWD traps in an Integrated Pest Management (IPM) program?

Monitoring for a pest is a cornerstone of an Integrated Pest Management (IPM) program. It allows early identification of the presence of the pest and the risk posed to the crop. To catch as many SWD as possible whether used at low density for general monitoring or high-density precision monitoring, Drosal Pro and DrosaLure should be used during all periods SWD are active, even if there is no crop present.  Spotted Wing Drosophila traps can be setup to monitor for adult flies in a number of ways with low densities (1 trap every 10-20 m) identifying general pest activity, or high density spacing (1 trap every 1-2 m) allowing high catches and mass or precision monitoring. One Drosal Pro trap should be filled with 75 ml of DrosaLure and the number of SWD caught counted weekly at which time the liquid bait should be replaced. Pouring liquid through a sieve or paint filter will remove flies to allow identification.

Spotted Wing Drosophila can use wild berries commonly found in woodland and hedgerow such as blackberries and sloes as hosts when a commercial crop is not available. Early warning of SWD activity can often be identified by placing traps in areas of crop bordering areas containing wild hosts. Traps can be used to intercept SWD flies as they move into the crop area. Adult SWD flies can survive through winter and first detection in spring will be dependent upon the severity of the previous winter. During summer, peak adult activity occurs at temperatures around 27°C but is significantly reduced when temperatures pass 30°C.

Trapping systems such as Drosal Pro and DrosaLure should be used alongside other SWD management practices including good crop hygiene, management of beneficial predator populations, use of Plant Protection Products (PPP) and netting.

Best practice for using SWD monitoring traps:

  • Monitoring of SWD should be carried out from March to November
  • Traps should be located around the outer edge of the crop or at tunnel ends
  • Place traps approximately 1 m above the ground
  • Position traps on the shady side of the crop
  • Clear vegetation from around trap so they are easily visible
  • Fill each Drosal Pro trap with approximately 75 ml DrosaLure
  • Replace DrosaLure every week
  • Pouring DrosaLure attractant through a filter will remove flies for identification
  • Dispose of used attractant away from the crop

More information on recommendations for SWD management can be found at the AHDB website (link https://horticulture.ahdb.org.uk/swd). The latest research on the pest can be found at the NIAB/EMR website (link http://www.emr.ac.uk/).


Benefits to the environment.

Understanding when a pest is present is key to planning an ecologically sound integrated pest management strategy. Identifying adult pest activity and planning future action is better both the environment and the farmer rather than reactive action when the more destructive stages of the life cycle are present. Precision monitoring around the perimeter of a crop area allows early identification of risk from a pest migrating into the crop and causing damage.

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