Foliage Intensity is an Important Cue of Habitat Location for Empoasca onukii

Abstract

<jats:p>For many herbivorous insects, vision is more important than olfaction in the prealighting stage of host habitat location. Tea leafhoppers, Empoasca onukii (Hemiptera, Cicadellidae), are serious pests that preferentially inhabit the tender leaves of tea plants across China. Here, we investigated whether tea leafhoppers could distinguish foliage colors associated with different leaf ages and use this visual cue to guide suitable habitat location from short distances. Similar to honeybees, the adult E. onukii has an apposition type of compound eye, and each ommatidium has eight retinular cells, in which three spectral types of photoreceptors are distributed, with peak sensitivities at 356 nm (ultraviolet), 435 nm (blue), and 542 nm (green). Both changes in spectral intensity and hue of reflectance light of the host foliage were correlated with varying leaf age, and the intensity linearly decreased with increasing leaf age. Behavioral responses also showed that adult E. onukii could discriminate between the simulated colors of host foliage at different leaf ages without olfactory stimuli and selected the bright colors that strongly corresponded to those of tender leaves. The results suggest that, compared with the spectral composition (hue), the intensity of light reflectance from leaves at different ages is more important for adult leafhoppers when discriminating host foliage and could guide them to tender leaves at the top of tea shoots.</jats:p>

Influence of meteorological factors on the quantitative following relationship between Empoasca onukii Matsuda (Hemiptera: Cicadellidae) and its natural enemies in tea plantations

“…Bian et al . (2020) discussed the ability of E. onukii to discriminate the color of host leaves, providing a reference for color‐based pest trapping and monitoring methods. Combining the results of this study with these findings, the control of E. onukii can be carried out in an integrated manner using various approaches, thus improving the efficiency of pest control.…”

Visual acuity of Empoasca onukii (Hemiptera, Cicadellidae)

“…The visual acuity of insects is closely related to their flight ability and range of movement. E. onukii adults are usually in a resting state, and leaf tenderness can be identified by foliage-reflected light intensity so that the most suitable living environment can be selected [6]. The single flight distance of E. onukii adults is very limited, and they mainly rely on spiral flight, curved crawling on the plane, and short hops through the tea plants.…”

“…The compound eyes of E. onukii are apposition eyes, which have tubular structures composed of the cornea, crystalline cones, and photoreceptor cells that transmit light to the rhabdom [5]. Multiple ommatidia cluster the identified images onto the retina, which is made up of several retinular cells [6]. In the insects' visual system, visual acuity is the parameter that helps them resolve static spatial details.…”

Mating and post-copulation behavior in the tea leafhopper, Empoasca onukii (Hemiptera: Cicadellidae)

“…At the top of each production branch is the tea bud, and below the bud are leaves of differing ages (i.e., the young leaves are closest to the buds, and the leaves increase in age with increasing distance from the bud). Empoasca onukii adults and nymphs prefer to feed on the mesophyll cells of the young leaves and stems ( Bian et al., 2018a ; Bian et al., 2020 ), so they are mostly distributed in the upper layer of production branches during feeding.…”