How to create a comprehensive IPM strategy to control thrips

Creating a pre-emptive strategy for thrips control is key to managing populations through this high-risk time in the year with increased temperatures bringing about a migration of flying thrips adults most notably originating from cereal crops as the harvest period looms and the thrips food source drops causing them to venture further afield where we often seen populations establish in horticultural crops.

Thrips have the potential to be very economically damaging to crops, causing a silvering effect on the leaf surface and damage to the flowers and fruit where the pest pierces into the plant and consumes the cells on the surface membrane. Damaging effects of thrips also include the transmission of plant viruses and plant distortion and if allowed to persist in high levels, death of the plant.

A key identification of thrips presence along with the described damage and location can also take place above or under the leaf depending on what species is present with black dots which can be observed within the damaged area. These black dots are frass which the pest excretes and will cover themselves in to defend against predatory species attacking them.

Important thrips species

Frankliniella occidentalis

The most economically damaging and present thrips species observed within protected growing environments in the UK, originating in North America with this pest now well distributed worldwide. This species through feeding also acts as a vector for Tomato Spotted Wilt Virus (TSWV) and Impatiens Necrotic Spot Virus (INSV).

Identification can be tricky as this species can be very similar in appearance to other thrips species, with colour ranging from pale to dark, with bands on abdominal segments appearing yellow to grey with a black stripe observed on the back when wings are folded.

Heliothrips haemorrhoidalis 

Originating in South America and now distributed worldwide, the adults are identified by their black thorax and abdomen with yellow legs. The colonies appear more concentrated on the upper side of the leaf surface than other species with larvae and adults closely packed together.

Non-native predators such as Amblyseius montdorensis and swirskii are recorded as having a higher efficacy of control with this species, with these species only licenced for application under permanent protection environments.

Thrips setosus

Originating from Japan and Korea this is one of the newer pest species we are observing in the UK and presenting an issue for growers with distortion of certain plant species for ornamental growers as well as from feeding damage and is a vector for tomato spotted wilt virus.

This species can be identified by its dark body and pale-yellow colouring at the top end of the wing that attaches to the body.

Predatory species such as Amblyseius cucumeris are not as effective with this species however, the non-native predator Amblyseius montdorensis and Swirskii has been recorded as having a higher efficacy of control with this species, with these species only licenced for application under permanent protection environments.

Creating a comprehensive control strategy with different elements is important to target the entire lifecycle of thrips.

Trapping

Starting off with the thrips migration as a winged adult the use of blue sticky rectangular and roll traps are extremely effective at catching the adults and when used correctly are the most important first line of defence for a thrips invasion.

There are varying trap colours with blue found to be the most effective for trapping thrips and yellow traps are also effective. The Optiroll sticky trap range are very extensively used and are very successful for trapping the flying adults and for positioning at crop height to trap emerging thrips from the soil after pupation. The Optiroll range contains an extensive list of colours with the Optiroll blue plus containing pheromone lure for trapping specifically western flower thrips Frankliniella occidentalis and include a printed pattern design on the trap to increase percentage catch.

In stock Optiroll Roller Trap 100m x 30cm - Blue

Optiroll Roller Trap 100m x 30cm - Blue

£65.71 Ex VAT

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In stock Optiroll Roller Trap Super Plus 100m x 30cm - Blue

Optiroll Roller Trap Super Plus 100m x 30cm - Blue

£42.59 Ex VAT

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Biological controls

When addressing thrips control using biologicals it is important to understand what biologicals target certain stages of the thrips lifecycle to establish a comprehensive control.

The Amblyseius mites make up the majority of the beneficial species applied for control of thrips and target the larval stages. The most effective Amblyseius species for control of thrips include, Amblyseius cucumeris, Amblyseius montdorensis and Amblyseius swirskii. These species come in an extensive range of sachets designs and loose product to suit your situation.

Amblyseius cucumeris

This is a very effective predatory mite of thrips and used widely for control of this pest targeting the larval stage, most notably for thrips species including, Western Flower Thrips and Onion thrips and many others and occurs naturally across temperate regions around the world, also targeting broad mite and cyclamen mite.

Application of this species can be made all year round however, for full activity temperatures should not be below 18˚C through light hours.

Fargro offers this predatory species as a loose product and in our sachet range containing a breeding colony and continuous release over 6-8 weeks.

Amblyseius montdorensis

First identified in, Queensland, Australia, and Pacific islands such as Fiji, this predatory mite species will predate young thrips, whitefly eggs, eriophyids and tarsonemid mites. Requiring temperature thresholds of 16˚C and above for full activity.

This species has been found to me more effective than Amblyseius cucumeris on certain non-native thrips species including Japanese thrips and Glasshouse thrips.

This predatory mite species is non-native and as such is sold under licence and must only be applied in fully protected enclosure environments to ensure this species does not reproduce outside of the glasshouse environment.

Fargro offers this predatory species as a loose product and in our sachet range containing a breeding colony and continuous release over 6-8 weeks.

Amblyseius swirskii

Originating from Egypt, this predatory mite is an effective predator for both thrips and whitefly. The origins of a warm climate require temperatures to be in excess of 25˚C for reproduction, with this predator used widely on protected sweet pepper and cucumber crops. Better establishment takes place on pollen producing crops as the polyphagous diet allows the mite to sustain itself on these pollens until populations of prey increase.

This predatory mite species is non-native and as such is sold under licence and must only be applied in fully protected enclosure environments to ensure this species does not reproduce outside of the glasshouse environment.

Fargro offers this predatory species as a loose product and in our sachet range containing a breeding colony and continuous release over 6-8 weeks.

Orius laevigatus/ Orius majusculus

Orius spp. is an important generalist being a true bug with a stabbing proboscis makes it an effective predator of all stages of thrips including the adults stage. This complements itself alongside Amblyseius species in targeting the larval stages with the predatory mites and the adults with Orius.

This predatory species does require a certain level of pollen to sustain populations in the environment if prey populations are low and we do offer a supplementary food to sustain populations early in the season if required. Orius laevigatus is the most widely applied species out of the two commercially available Orius species, Orius majusculus are sold as a separate product with this species establishing better on crops such as cucumber than Orius laevigatus.

Fargro offers this predator as a loose product to be directly applied to plant foliage as nymphs, adults or both as a mix.

Hypoaspis miles

Hypoaspis is a ground dwelling predatory mite and due to where this species predates in the soil it will predate on thrips pupating in the soil when the fall off the plants during this stage in their lifecycle.

Fargro offers this predatory species as a loose product to be directly applied to the soil media.

Chemical control

Naturalis-L is an effective biological insecticide for reducing thrips under permanent protection environments and contains the entomopathogenic fungus active Beauveria bassiana which is compatible alongside beneficial species.

In stock Naturalis-L Biological Insecticide 1lt

Naturalis-L Biological Insecticide 1lt

£62.40 Ex VAT

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Get in touch

For more information, please contact biosales on 01903 256857 or biosales@fargro.co.uk