Related but not alike: not all Hemiptera are attracted to yellow

Abstract

Most innate responses to color stimuli lead herbivorous insects to orient to "green" and "yellow" surfaces. Early research showed that aphid orientation to plants is influenced by foliar pigments and leads them to alight on leaves of a specific physiological state regardless of whether or not it is their actual host. In this study, we quantified the color preferences of four psyllids specialized on young to recently expanded leaves of different Eucalyptus hosts presenting distinct between (inter-specific) and within canopy (ontogenic) optical characteristics. Color preferences of Ctenarytaina eucalypti and C. bipartita were similar to those observed in aphids with more frequent selection of yellow and green stimuli, consistent with the coloration of their host leaves. However, attraction of Anoeconeossa bundoorensis and Glycaspis brimblecombei to a red stimulus contrasts strongly with the literature for hemipteran and herbivorous insects generally for which attraction to red is peculiar. Interestingly, both red-attracted species occur on the same host eucalypt, which expresses anthocyanic (red) young leaves. Our experiments demonstrate that these two species are sensitive to long wavelength radiation. Behavioral responses and modeling of putative "aphid-like" photoreceptors were conducted to investigate whether achromatic vision mediates perception of "red." Our results do not provide strong evidence for an intensity-dependant type of attraction. Nevertheless, the current knowledge of photoreceptors in Hemiptera identifies the achromatic pathway as the most likely mechanism for detecting long wavelengths. Thus, our findings highlight the need for physiological work with Psylloidae to elucidate the mechanisms responsible for such atypical responses. We discuss the ecological implications of our work in relation to red foliar pigments in expanding leaves of perennial plants which differs greatly from the thoroughly studied aphid-autumnal leaves system involving senescing foliage.

Visual acuity trade-offs and microhabitat driven adaptation of searching behaviour in psyllids (Hemiptera: Psylloidea: Aphalaridae)

“…The preference of A. bundoorensis and G. brimblecombei for red stimuli over black in Y-maze experiments was not influenced by the size of the stimuli. This concurs with previous work that demonstrated a pronounced preference for the 'red' stimulus over achromatic stimuli of higher intensity contrast with the background and suggests that psyllid innate colour responses are consistent independent of stimulus size (Farnier et al, 2014). Morphological measurements of psyllid eyes also revealed prominent differences.…”

“…Specifically, Anoeconesossa bundoorensis and Glycaspis brimblecombei, which share the same host (Eucalyptus camaldulensis) that produces young 'red' anthocyanic leaves, are primarily attracted to long wavelength-rich 'red' stimuli. In contrast, Ctenarytaina eucalypti (bluegum psyllid) and Ctenarytaina bipartita were shown to prefer 'yellow ' and 'green' stimuli (Brennan and Weinbaum, 2001;Farnier et al, 2014). Thus, we have evidence that psyllid colour preferences are adaptations of their visual system to facilitate their search for food and oviposition sites.…”

“…In this way, we could modify a conventional method to assess psyllid visual acuity to infer the subtended angle value at which particular colour targets are perceived and attract different species. Although a lack of information about psyllid spectral sensitivities remains a challenge for more fully elucidating the existence of colour vision in psyllids, the current study together with our previous work on innate preferences, and modelled likely photoreceptor distributions (Farnier et al, 2014), provide good reason to investigate the possibility of physiological colour processing mechanisms in these ecologically and biologically important models along the lines of the framework provided by Kemp et al (2015). Our findings reveal that psyllids possess relatively poor visual acuity -comparable to that of aphids (Land, 1997;Döring and Spaethe, 2009).…”

“…The recent study by Farnier et al (2014) also showed that colour preferences vary between different species of Eucalyptus-feeding psyllids. Specifically, Anoeconesossa bundoorensis and Glycaspis brimblecombei, which share the same host (Eucalyptus camaldulensis) that produces young 'red' anthocyanic leaves, are primarily attracted to long wavelength-rich 'red' stimuli.…”

“…Here, we thus use the term 'colour vision' with respect to psyllids because: (1) the existence of different classes of photoreceptors (i.e. UV, blue, green) has been demonstrated in a number of closely related hemipteran species (Briscoe and Chittka, 2001), including some insects belonging to the same suborder Sternorrhyncha such as aphids (Kirchner et al, 2005;Döring et al, 2011) and whiteflies (Mellor et al, 1997); (2) a colour opponent mechanism has been shown to exist in aphids (Döring and Chittka, 2007);and (3) there is recent evidence for intensity-independent preferences for colours in Eucalyptus-inhabiting psyllids (Farnier et al, 2014).…”