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

Lei Bian,Zhao Qun Li,Zong Mao Chen,Zong Xiu Luo,Xiao Ming Cai

doi:10.3390/insects11070426

Lei Bian, Zhao Qun Li + Show 3 more

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https://doi.org/10.3390/insects11070426

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Abstract

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.

Highlights

IntroductionA small hemipteran insect, is a serious pest of tea plants. The distribution ofE. onukii in tea shoots is very regular, with active adults inhabiting the first to fourth leaf below the bud in growing tea shoots [1] and with most female adults preferring the second leaf to complete oviposition [2,3]
Empoasca onukii, a small hemipteran insect, is a serious pest of tea plants
Similar to Callitettix versicolor [31] and E. vitis [8], the adult E. onukii has an apposition type of compound eye because the crystalline cone directly connects to the rhabdom and the clear zone was not found

Summary

Introduction

A small hemipteran insect, is a serious pest of tea plants. The distribution ofE. onukii in tea shoots is very regular, with active adults inhabiting the first to fourth leaf below the bud in growing tea shoots [1] and with most female adults preferring the second leaf to complete oviposition [2,3]. Host habitat location by most herbivorous insects is mediated by the interplay between chemical and visual cues [4,5,6]. For members of the genus of Empoasca, most species detect suitable habitats based mainly on visual cues. Chemical stimuli from the foliage of cotton could only be detected by Empoasca devastans from 1 cm, but visual stimuli were effective at up to 3.6 m (i.e., vision is the only option for E. devastans from a range from 1 cm to 3.6 m) [7]. Odors from the host were unable to attract E. vitis over long distances (>20 cm), across which visual cues (color) are the dominant information for E. vitis in selecting habitat [8]. Visual cues may play an important role in habitant location at a distance for E. vitis adults

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