Fig 1.
Schematic diagram of the bioassay apparatus for evaluation of phototactic psyllid responses to visual targets.
A vial containing psyllids was placed within the holding chamber, the manual shutter closed for dark adaptation and the top covered with two semi-circular colored filters. The shutter was opened to allow psyllids into the arena and responding psyllids were captured on the sticky layer beneath the filters.
Fig 2.
Transmission spectra through a clear Petri dish in conjunction with filters used in two-choice assays.
(A) No filter vs UV-blocking filter. (B) Yellow filter alone, yellow with UV-blocking filter, and yellow filter with one and two neutral density filters. (C) Blue filter vs blue filter with UV-blocking filter. (D) Green filter vs green filter with UV-blocking filter.
Fig 3.
Intensity (μWatts/cm2) of light transmitted (350–700 nm) through single and double filters used in two-choice assays.
UV = UV-blocking filters, ND = neutral density filters.
Fig 4.
Reflectance spectra of vegetation, psyllids and fruit.
(A) Young leaves/flush, mature leaves, and flower of orange jasmine Murraya paniculata (B) Wings of male and female Asian citrus psyllids and honeydew excreted by nymphs (C) Peel of grapefruit, lemon, lime and orange jasmine fruit (D) Healthy flush and mature leaves of orange, Citrus sinsensis (E) Huanglongbing-diseased flush, and ‘green’ and ‘yellow’ portions of the infected leaves of C. sinsensis.
Fig 5.
Responses (mean ± SE) of psyllids in two-choice assays to visual targets with clear, green, yellow and UV-blocking filters.
(A) Clear filter vs. clear with UV-blocking filter, (B) Yellow filter vs. green filter, (C) Yellow and UV-blocking filter vs. green filter, (D) Green and UV-blocking filter vs. yellow and UV-blocking filter. Different letters above columns indicate significant differences (P < 0.05).
Fig 6.
Responses (mean ± SE) of D. citri in two-choice assays to visual targets with blue, yellow and UV-blocking filters.
(A) Yellow filter vs. blue filter, (B) Yellow and UV filter vs. blue filter, (C) Yellow and UV filter vs. blue and UV filter, (D) Clear filter vs. clear with blue filter. Different letters above columns indicate significant differences (P < 0.05).
Fig 7.
Responses (mean ± SE) of D. citri in two-choice assays to visual targets with clear, yellow, green and UV-blocking filters.
(A) Clear filter vs. yellow filter, (B) Clear filter vs. green filter, (C) Yellow and UV-blocking filter vs. yellow with neutral density (filter) and UV filter, (D) Yellow and UV-blocking filter vs yellow with two neutral density filters. Different letters above columns indicate significant differences (P < 0.05).