Monitoring and trapping with sticky traps, what’s new?

One hundred years ago, it was observed that greenhouse whiteflies, Trialeurodes vaporariorum (Westwood) (Hemiptera, Aleyrodidae) are particularly attracted to opaque yellow traps (Lloyd, 1921). Today, millions of sticky traps (card or plastic covered with a thin layer of a clear adhesive substance) of different colours are used worldwide. They are used for the monitoring, decision making (Böckmann et al, 2015), and mass trapping (Sampson and Kirk, 2013), of flying crop pests as part of Integrated Pest Management (IPM). This article explores how traps are used today, recent developments and the next steps needed to make the best use of these simple tools.To get more news about Yellow Sticky Traps, you can visit senpinghz.com official website.

The attraction of colour
Colours are used by insect pests to locate host plants (Prokopy & Owens, 1983). Yellow traps, with high reflectance in the long-wave region from green to red (about 500-640 nm) and low reflectance in the short-wave region from UV to blue (about 300-500 nm), are particularly attractive to leaf-feeding insects, such as aphids, small flies, thrips and whiteflies (Figure 1a). Flower and fruit-visiting insects are often attracted to the colour of their host’s flowers or fruit (Kirk, 1984): The spotted wing drosophila (SWD), Drosophila suzukii, which lays its eggs in berry fruit, has an attraction to red (Kirkpatrick et al., 2017); The western flower thrips (WFT), Frankliniella occidentalis, typically shows preference for blue traps (440-460nm) in greenhouse grown crops (Figure 1b).
Other features of the trap can affect trap catch, such as background, length of edge, shape, position, and surface texture (Vernon and Gillespie, 1995). Relative attraction can be affected by ambient light conditions, or be enhanced by LEDs. The selection of the best trap colour will depend on the purpose of trapping. Yellow sticky traps are a good choice for monitoring a wide range of pest species on a single trap (Figure 2a,b). Other trap colours, such as blue for thrips and capsids or red for SWD, are more appropriate when a grower is selecting traps to maximise the catch of specific species. Sometimes less attractive trap colours are selected in order to minimise the catch of non-target insects, including predators and pollinators. For example,

black sticky traps (Black impact traps, Russell IPM) are combined with a species-specific pheromone to catch the marmorated stink bug, Halyomorpha halys. This ensures that only the target pests are caught, making the pests easier to identify and count. Sticky traps are available with different glue types, which affects the range of species caught. The strongest glue is sold with a peel-off silicon paper (eg Impact traps, Russell IPM), which is required to capture larger species such as marmorated stink bug. Traps are also available with tacky ‘wet’ glue which retain high catch rates of small pest species, such as whiteflies, but from which larger species can escape (eg Hytak traps, Russell IPM). These are used to reduce by-catch of some of the larger predators and pollinators, such as lacewings, Orius and bees.

Insect behaviour is partly controlled by semiochemicals (scents), such as pheromones, kairomones and their analogues, which are used to locate mates and plant hosts. These can be added to sticky traps to increase trap catch. The scents can be added as individual lures, or encapsulated for longer release and added to the glue within the sticky traps (eg Optiroll super plus, Russell IPM). A number of attractants, including (E)-2-Hexenal and 3-Hexen-1-ol and Linalool, have been identified to attract the glasshouse whitefly, yet few have been found effective in the field or developed commercially (Schlaeger et al, 2018). In contrast, many attractants have proved effective against WFT and a range of thrips attractants are available commercially (Kirk et al, 2021). In experiments in greenhouse strawberry, adding the aggregation pheromone, neryl (S)-methyl butanoate (Thripline AMS, Bioline Agrosciences), the kairomone analogue methyl isonicotinate (Lurem-T, Koppert) and a mix of floral scents (Thripnok, Russell IPM) to yellow sticky traps, enhanced trap catch of the western flower thrips, by 50-300% (Figure 3).

The best choice of attractant will depend on the crop and thrips species present. Whereas the western flower thrips aggregation pheromone is highly specific to WFT, kairomones and their analogues are more generally attractive to a range of flower-inhabiting thrips species. A range of lures are available for different pest species. In raspberry, adding a fruit volatile lure (SWD lure, Russell IPM) to red sticky traps increased trap catch of spotted wing drosophila by x46, making the trap and lure combinations a convenient and sensitive monitoring tool (Figure 4).