Wavelength and polarization affect phototaxis of the Asian citrus psyllid

Authors: THOMSON, PARIS - University Of Florida; Allan, Sandra - Sandy; UDELL, BRADLEY - University Of Florida; STANSLY, PHILIP - University Of Florida

Submitted to: Insects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2017
Publication Date: 8/19/2017
Citation: Thomson, P., Allan, S.A., Udell, B.J., Stansly, P.A. 2017. Wavelength and polarization affect phototaxis of the Asian citrus psyllid. Insects. 8(3):88. https://doi.org/10.3390/insects8030088.
DOI: https://doi.org/10.3390/insects8030088

Interpretive Summary: The Asian citrus psyllid poses a major threat to the citrus industry in the US due to its role as a vector of devastating citrus disease, huanglongbing. Control of the insects is through pesticide application and requires effective surveillance methods to help guide optimal management protocols. Currently a yellow sticky trap is the most common surveillance method, however it is not effective at psyllid populations levels. In this study, a scientist at USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, Florida, along with scientists at the University of Florida evaluated aspects of vision of the psyllids to obtain better insight into methods of attraction of psyllids. In laboratory assays, the roles of polarized light, ultraviolet and green light were evaluated in attraction and movement of psyllids. Green and UV light played different roles in stimulating or suppressing movement of psyllids. Polarized of light enhanced attraction to white light sources. This role of polarized light has potential for enhancing current surveillance technology for this species, which in turn would provide better protection of vulnerable citrus to infestation with psyllids and establishment of huanglongbing.

Technical Abstract: The Asian citrus psyllid, D. citri, is a primary pest for citrus production due to its status as a vector of the citrus disease, huanglongbing. We investigated phototactic behavior of D. citri to evaluate effects of light of specific wavelength or polarization using a horizontal bioassay arena. Wavelength-associated positive phototaxis was associated with low wavelength UV (350-405 nm) targets with low responses to long wavelength green/yellow targets (500-620 nm). Distance walked towards the visual target was greater for UV/blue wavelengths (350- 430 nm) than for long wavelengths. Distances walked towards 365 nm light were greater than to white light and distances travelled to long wavelength light were similar to those in darkness. Decreased light intensity decreased responses to white and UV (365 nm) light. Polarized light was discriminated and D. citri travelled greater distance in response to white vertically polarized light than to horizontally polarized light or nonpolarized light equal in intensity. There were no differences in response between vertically or horizontally polarized light for 405 nm and 500 nm light. Responses to the polarized light at 405 nm were greater than to nonpolarized light. For 500 nm light, there was no difference between responses to polarized or nonpolarized light. There was no effect of age on responses to 405 nm light, however 1 day old psyllid travelled faster in the presence of 500 nm green compared to 4-7 day old psyllids.