Colour vision in thrips (Thysanoptera)

Abstract

Insects are an astonishingly successful and diverse group, occupying the gamut of habitats and lifestyle niches. They represent the vast majority of described species and total terrestrial animal biomass on the planet. Their success is in part owed to their sophisticated visual systems, including colour vision, which drive a variety of complex behaviours. However, the majority of research on insect vision has focused on only a few model organisms including flies, honeybees and butterflies. Especially understudied are phytophagous insects, such as diminutive thrips (Thysanoptera), in spite of their damage to agriculture. Thrips display robust yet variable colour-specific responses despite their miniaturized eyes, but little is known about the physiological and ecological basis of their visual systems. Here, we review the known visual behavioural information about thrips and the few physiological studies regarding their eyes. Eye structure, spectral sensitivity, opsin genes and the presence of putative colour filters in certain ommatidia strongly imply dynamic visual capabilities. Finally, we discuss the major gaps in knowledge that remain for a better understanding of the visual system of thrips and why bridging these gaps is important for expanding new possibilities for applied pest management strategies for these tiny insects. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in arthropods’.

High diversity of arthropod colour vision: from genes to ecology

“…[101]), and preference for light of long wavelengths is found in many herbivorous pest insects, which either feed or oviposit on green leaves [102,103]. López Reyes et al [62] review what is presently known for thrips (the insect order Thysanoptera), and Döring & Kirchner [104] provide a model explaining the choice of aphids (Hemiptera) for substrates appearing green or yellow to the human eye.…”

“…stomatopods: [61]; reviewed by [20]), where some of them influence spectral sensitivity. By contrast, López Reyes et al [62] report that the function of fluorescing filters observed in thysanopteran insects (thrips) still awaits understanding. Filter pigments can also be placed more proximally in the light path, affecting only part of the photoreceptors.…”

Tracking the flight and landing behaviour of western flower thrips in response to single and two-colour cues

“…Monitoring for WFT by its attraction to coloured sticky traps, in conjunction with chemical lures, capitalises on a natural behavioural response to colour while searching for potential host plants 1 . The WFT is known to show preferences to specific colours indicating colour discrimination capabilities, having a high response to blue and yellow and sometimes to UV-A light 2 . From the few electroretinogram (ERG) studies that have been conducted on WFT eyes, sensitivity peaks are found at ~ 360–365 (UV-A light) 3 , and at ~ 500–540 nm (green light) 3 , 4 , which is consistent with the presence of UV-A and green photoreceptors.…”

“…Behavioural studies also suggest that a blue photoreceptor is present 5 , which would increase the number of colours WFT is able to perceive and discriminate. However, there is ongoing debate regarding the most attractive colour to optimize WFT catches, especially between blue and yellow 2 , 6 . To date, much of the research on WFT trapping is based on measuring the number of landings on a target 2 , 7 .…”

“…However, there is ongoing debate regarding the most attractive colour to optimize WFT catches, especially between blue and yellow 2 , 6 . To date, much of the research on WFT trapping is based on measuring the number of landings on a target 2 , 7 . This end-point data quantifies the overall efficacy of colour cues but provides no information about how their behaviour is influenced when approaching visual cues.…”