The Power of Electropenetrography in Enhancing Our Understanding of Host Plant-Vector Interactions

Abstract

The invasive Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), is the primary vector of the phloem-infecting bacterium, Candidatus Liberibacter asiaticus. Candidatus L. asiaticus is the putative causal agent of Huanglongbing (HLB) disease, a destructive disease of Citrus. While many Citrus species are susceptible to D. citri probing and HLB disease, there are marked behavioral differences in D. citri probing responses and Ca. Liberibacter asiaticus infection severity among Citrus species. Using four mandarin hybrid selections and pummelo plants variably resistant to D. citri probing, oviposition, and survival, we explored probing differences using electropenetrography (EPG), conducted an oviposition and survival study, and determined host plant metabolites using gas-chromatography mass-spectroscopy (GC-MS). We found thirty-seven D. citri probing variables to be significantly different among tested mandarin selections and pummelo, in addition to differential oviposition and survivorship abilities on tested plants. We found sixty-three leaf metabolites with eight being significantly different among tested mandarin selections and pummelo. Detailed analysis of probing behavior, oviposition, survivorship, and host plant metabolite concentrations reveals the complex, layered resistance mechanisms utilized by resistant Citrus against D. citri probing. EPG is a powerful technology for screening Asian citrus psyllid resistant Citrus to elucidate host plant-vector interactions, with an aim to minimize vector probing and eliminate the spread of the bacterial pathogen, Ca. L. asiaticus.

Xylella fastidiosa inoculation behaviors (EPG X wave) are performed differently by blue-green sharpshooters based on infection status of prior probing host

“…It enabled us to ‘tease apart’ the various mechanisms underlying stylet probing decisions by the insects. Thus, the ‘power of electropenetrography’ (Shugart et al 2019) lies in its ability to measure in real-time the direct effects of a temporally dynamic process, that is, reciprocal interactions between microbial titer and vector stylet probing.…”

Different Host Plants Distinctly Influence the Feeding Ability of the Brown Citrus Aphid Toxoptera citricida

“…Maybe denser and longer nonglandular trichomes on stems than on either leaf surface interrupts and slows down feeding by herbivores [50]. Factors of mesophyll tissue resistance include cell wall resistance to the physical and chemical penetration of the pest insects [51]. In order to elucidate the cause of this prolonged pathway, further studies will be necessary.…”

Common resistance mechanisms are deployed by plants against sap-feeding herbivorous insects: insights from a meta-analysis and systematic review

“…Resistance mechanisms active in this tissue have been described against multiple sap-feeding herbivorous insect groups: reduced amino acid content contributes towards aphid resistance in barley 31 and other Poaceae species 54 , higher sugar composition and lower serine content have been described in Citrus spp. that are resistant to psyllids 55 , and sieve element occlusion is a well reported resistance mechanism in Cucurbitaceae that helps to restrict phloem feeding from aphids 56 .…”