Feeding behaviour of a virus‐vector leafhopper on host and non‐host plants characterised by electrical penetration graphs

Abstract

Many sap-feeders are vectors of plant diseases, acquiring and inoculating pathogens at various stages of the feeding process. In oligophagous species, certain aspects of probing behaviour on hosts and non-hosts may have implications for the range of both pathogens and plants that can be inoculated. We addressed the question of which probing phases (including ingestion) occur on non-host plants in the case of the common leafhopper Psammotettix alienus (Dahlbom) (Hemiptera: Cicadellidae). This species is a pest on cereals, a vector of the Wheat dwarf virus, and possible carrier of other pathogens. It is regarded as oligophagous on grasses, but has been reported also on other plant families. In a combined electrical penetration graph (EPG) video observation study, we aimed to give a description of the waveforms during the probing process. EPG recordings were made on a suitable host, barley, Hordeum vulgare L. (Poaceae), and on two non-host plants, the sedge Carex tomentosa L. (Cyperaceae) and the ragweed Ambrosia artemisiifolia L. (Asteraceae). We demonstrated that P. alienus probes on plants other than Poaceae, including dicotyledons. Univariate and multivariate analyses of general probing variables revealed that total and maximal probe durations were shorter and probing progress less advanced on non-host plants. Waveforms of the pathway phase were stereotypical and statistically not different between the host and non-host plants. On sedge, the waveform signifying insertion through the plant epidermis was shortened but much more frequent, indicating penetration difficulties and retrials. Most importantly, waveforms indicating phloem ingestion were not present on either of the non-host plants. Non-host probing events terminating during the pathway phase suggested that rejection occurred when the stylets were in the mesophyllum. Overall, the EPG signals reflected the unsuitability of A. artemisiifolia and C. tomentosa compared to barley, but the occurrence of probing and the demonstrated level of probing progress imply that pathogen transmission cannot be excluded in the case of many non-host plants and non-specific pathogens.

Plant penetration activities by the flatid planthopper Metcalfa pruinosa (Hemiptera: Fulgoroidea): an electrical penetration graph‐histology analysis

“…However, more direct and detailed evidence related to the phloem and xylem sap ingestion of M. pruinosa in the Mp4 and Mp5 waveforms needs to be obtained. We also observed the Mp6 waveform in which feeding activity corresponded to the unknown waveform of the leaf- (Tholt et al 2015). Because the Mp6 waveform usually followed the Mp5, Mp6 seems to be related to an activity in the xylem region.…”

“…) and Ps3 of the European grass‐feeding leafhopper, Psammotettix alienus Dahlbom (Cicadellidae) in wave shape and occurrence after xylem feeding (Tholt et al. ).…”

“…Psammotettix alienus Dahlbom (Cicadellidae) in wave shape and occurrence after xylem feeding (Tholt et al 2015).…”

“…Such EPG signal patterns are correlated with insect feeding behaviour and honeydew excretion (Tjallingii 1978;Tjallingii and Hogen Esch 1993;Seo et al 2009). Therefore, EPG has been used to understand insect probing behaviour on host or non-host plants (Calatayud et al 1994;Tholt et al 2015), to screen resistant plants (Gabrys et al 1997;Klingler et al 1998), to locate which parts of plant tissues resist insect feeding (Lei et al 1999;Jiang et al 2001;Alvarez et al 2006;Seo et al 2010), to investigate probing behaviour after knockdown of gene expression (Mutti et al 2008), to understand probing behaviour related to pathogen transmission (Mart ın et al 1997;Johnson et al 2002;Moreno-Delafuente et al 2013) and to determine the effects of insecticide or artificial diet on insect feeding behaviour (He et al 2011;Jin et al 2012;Civolani et al 2014).…”

Previous infestation withPsammotettix alienuson spring wheat seedlings decreased the fitness ofSitobion avenaein a subsequent infestation

“…The European grass‐feeding leafhopper Psammotettix alienus Dahlbom (Hemiptera: Cicadellidae) and the English grain aphid S. avenae occur sequentially on cereal crops worldwide, especially in Europe (Alla et al ., ; Liu et al ., ; Yazdkhasti, ; Luo et al ., ; Tholt et al ., ). To date, most studies that have examined the fitness of cereal aphids focused on the effects of feeding on host plants that were previously fed on by different species of cereal aphids or were infected with the virus transmitted by cereal aphids.…”