Potato Psyllid (Hemiptera: Triozidae) Behavior on Three Potato Genotypes With Tolerance to 'Candidatus Liberibacter solanacearum'

Biology, Ecology, and Management of the Potato Psyllid, Bactericera cockerelli (Hemiptera: Triozidae), and Zebra Chip Disease in Potato

The potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae), transmits the pathogen "Candidatus liberibacter solanacearum" (Lso), the putative causal agent of zebra chip disease (ZC). ZC is a disease of potato that reduces yield and quality and has disrupted integrated pest management programs in parts of the Americas and New Zealand. Advances in our understanding of the ecological factors that influence ZC epidemiology have been accelerated by the relatively recent identification of Lso and motivated by the steady increase in ZC distribution and the potential for devastating economic losses on a global scale. Management of ZC remains heavily reliant upon insecticides, which is not sustainable from the standpoint of insecticide resistance, nontarget effects on natural enemies, and regulations that may limit such tools. This review synthesizes the literature on potato psyllids and ZC, outlining recent progress, identifying knowledge gaps, and proposing avenues for further research on this important pathosystem of potatoes.

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

Despite their abundance and economic importance, the mechanism of plant resistance to sap-feeding insects remains poorly understood. Here we deploy meta-analysis and data synthesis methods to evaluate the results from electrophysiological studies describing feeding behaviour experiments where resistance mechanisms were identified, focussing on studies describing host-plant resistance and non-host resistance mechanisms. Data were extracted from 108 studies, comprising 41 insect species across eight insect taxa and 12 host-plant families representing over 30 species. Results demonstrate that mechanisms deployed by resistant plants have common consequences on the feeding behaviour of diverse insect groups. We show that insects feeding on resistant plants take longer to establish a feeding site and have their feeding duration suppressed two-fold compared with insects feeding on susceptible plants. Our results reveal that traits contributing towards resistant phenotypes are conserved across plant families, deployed against taxonomically diverse insect groups, and that the underlying resistance mechanisms are conserved. These findings provide a new insight into plant-insect interaction and highlight the need for further mechanistic studies across diverse taxa.

A comprehensive review of zebra chip disease in potato and its management through breeding for resistance/tolerance to 'Candidatus Liberibacter solanacearum' and its insect vector

Zebra chip disease (ZC), associated with the plant pathogenic bacterium 'Candidatus Liberibacter solanacearum' (psyllaurous) (CLso), is a major threat to global potato production. In addition to yield loss, CLso infection causes discoloration in the tubers, rendering them unmarketable. CLso is transmitted by the potato psyllid, Bactericera cockerelli (Šulc) (Hemiptera: Triozidae). ZC is managed by prophylactic insecticide applications to control the vector, which is costly and carries environmental and human health risks. Given the expense, difficulty, and unsustainability of managing vector-borne diseases with insecticides, identifying sources of resistance to CLso and developing varieties that are resistant or tolerant to CLso and/or potato psyllids has become a major goal of breeding efforts. These efforts include field and laboratory evaluations of noncultivated germplasm and cultivars, studies of tubers in cold storage, detailed quantifications of biochemical responses to infection with CLso, possible mechanisms underlying insect resistance, and traditional examination of potato quality following infections. This review provides a brief history of ZC and potato psyllid, a summary of currently available tools to manage ZC, and a comprehensive review of breeding efforts for ZC and potato psyllid management within the greater context of Integrated Pest Management (IPM) strategies. © 2022 Society of Chemical Industry. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Chili Pepper Jojutla Morelos (Capsicum annuum L.), CJ-2018: A Variety Resistant to Bactericera cockerelli

Chili pepper is a vegetable of worldwide economic and gastronomic importance. The psyllid, Bactericera cockerelli, is an economically important pest in this crop, causing considerable losses in its production. Currently, the application of insecticides is the main way to control B. cockerelli. However, the use of varieties resistant to this insect is a viable alternative for its control and management. In this work, the oviposition rate, development, and survival of B. cockerelli in two native varieties of chili were evaluated. Choice and non-choice trials showed that the B. cockerelli oviposition was reduced on CJ-2018 by 92.17 and 80.18%, respectively, compared to the control. In CM-334, the insect showed a behavior similar to the control in the non-choice test, while in the choice test it laid more eggs on CM-334 compared to the control. The development and survival assay showed that only 1.33% of the eggs managed to reach the adult stage on CJ-2018. In contrast, on CM-334 the survival of B. cockerelli was similar to the control. These results suggest that CJ-2018 presented a resistance based on antixenosis and antibiosis against B. cockerelli.

Identification and Characterization of Potato Zebra Chip Resistance Among Wild Solanum Species

Potato zebra chip (ZC) disease, associated with the uncultured phloem-limited bacterium, Candidatus Liberibacter solanacearum (CLso), is transmitted by the potato psyllid Bactericera cockerelli. Potato ZC disease poses a significant threat to potato production worldwide. Current management practices mainly rely on the control of the psyllid to limit the spread of CLso. The present study investigated new sources of ZC resistance among wild Solanum species. A taxonomically diverse collection of tuber-bearing Solanum species was screened; one ZC-resistant accession and three ZC-tolerant accessions were identified among the 52 screened accessions. Further characterization of the resistant accession showed that the resistance was primarily associated with antibiosis effects due to differences in leaf trichome density and morphology of the wild accession, which could limit the psyllid feeding and oviposition. This germplasm offers a good resource for further understanding ZC and psyllid resistance mechanisms, contributing to potato breeding efforts to develop ZC resistance cultivars. Alternatively, it could be used as a potential trap crop to manage psyllid and control ZC disease.

Potato Zebra Chip: An Overview of the Disease, Control Strategies, and Prospects

Potato (Solanum tuberosum L.) is an important food crop worldwide. As the demand for fresh and processed potato products is increasing globally, there is a need to manage and control devastating diseases such as zebra chip (ZC). ZC disease causes major yield losses in many potato-growing regions and is associated with the fastidious, phloem-limited bacterium Candidatus Liberibacter solanacearum (CLso) that is vectored by the potato-tomato psyllid (Bactericera cockerelli Šulc). Current management measures for ZC disease mainly focus on chemical control and integrated pest management strategies of the psyllid vector to limit the spread of CLso, however, they add to the costs of potato production. Identification and deployment of CLso and/or the psyllid resistant cultivars, in combination with integrated pest management, may provide a sustainable long-term strategy to control ZC. In this review, we provide a brief overview of the ZC disease, epidemiology, current management strategies, and potential new approaches to manage ZC disease in the future.