Bactericera Cockerelli Research Articles

Treatment of Rapamycin and Evaluation of an Autophagic Response in the Gut of Bactericera cockerelli (Sulč)

Autophagy is a catabolic process that results in the autophagosomic-lysosomal degradation of bulk cytoplasmic content, abnormal protein aggregates, and excess of/or damaged organelles to promote cell survival. Autophagy is also a component of innate immunity in insects and is involved in the clearance of pathogens, including bacteria. The potato psyllid, Bactericera cockerelli, transmits the plant bacterial pathogen 'Candidatus Liberibacter solanacearum' (Lso) in the Americas and causes serious damage to solanaceous crops. Our previous studies showed that autophagy could be involved in the psyllid response to Lso and could affect pathogen acquisition. However, the tools to evaluate this response have not been validated in psyllids. To this end, the effect of rapamycin, a commonly used autophagy inducer, on potato psyllid survival and the expression of autophagy-related genes was evaluated. Further, the autophagic activity was assessed via microscopy and by measuring the autophagic flux. Artificial diet-feeding assays using rapamycin resulted in significant psyllid mortality, an increase in the autophagic flux, as well as an increase in the amount of autolysosomes. This study represents a stepping stone in determining the role of autophagy in psyllid immunity.

Life history and behavior of Tamarixia triozae parasitizing the tomato-potato psyllid, Bactericera cockerelli

Tamarixia triozae is an important primary parasitoid of the tomato-potato psyllid, Bactericera cockerelli, a serious cosmopolitan pest of solanaceous crops. However, without better information about its life history and behavior, it will be difficult to use this parasitoid in effective biological control programs. We carried out a series of experiments to characterize its parasitism, adult feeding, and oviposition behaviors and its sex allocation in response to different life stages of its host, and their fitness consequences. We show that T. triozae females fed on all host instars with a preference for mid-aged ones, and preferred to parasitize later instars, thus inflicting mortality on all instars simultaneously. Host feeding and parasitism peaked during the first week of female life and declined markedly after two weeks. Parasitoids allocated more fertilized eggs to older and larger nymphs, and superparasitism declined with increasing host density. The oviposition rate of fertilized eggs peaked when females were four to five days old, with > 90 % of daughters produced during the first half of adult life. The body size and egg loads of progeny increased with increasing host instar at parasitism, demonstrating a positive relationship between the host size and offspring fitness.

A Portable Chamber for Experimental Observations of Bactericera Cockerelli on Plant Seedlings and Leaves

Se describe una cámara de plástico portátil y económica para observaciones durante semanas del desarrollo y reproducción de el psílido de la papa y tomate, Bactericera cockerelli en material vegetal bajo condiciones controladas. Esta cámara también se puede utilizar para otros insectos.

Association of Two Bactericera Species (Hemiptera: Triozidae) With Native Lycium spp. (Solanales: Solanaceae) in the Potato Growing Regions of the Rio Grande Valley of Texas.

Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) is a vector of 'Candidatus Liberibacter solanacearum' (Lso), the pathogen that causes potato zebra chip. Zebra chip incidence varies regionally, perhaps because of geographic differences in species of noncrop hosts available to the vector and in susceptibility of those hosts to Lso. Native and introduced species of Lycium (Solanales: Solanaceae) are important noncrop hosts of B. cockerelli in some regions of North America. Susceptibility of native Lycium species to Lso is uncertain. We investigated the use of two native species of Lycium by B. cockerelli in South Texas and tested whether they are susceptible to Lso. Bactericera cockerelli adults and nymphs were collected frequently from L. berlandieri Dunal and L. carolinianum Walter. Greenhouse assays confirmed that B. cockerelli develops on both species and showed that Lso infects L. carolinianum. Molecular gut content analysis provided evidence that B. cockerelli adults disperse between potato and Lycium. These results demonstrate that L. berlandieri and L. carolinianum are likely noncrop sources of potato-colonizing B. cockerelli in South Texas and that L. carolinianum is a potential source of Lso-infected psyllids. We also routinely collected the congeneric psyllid, Bactericera dorsalis (Crawford), from both Lycium species. These records are the first for this psyllid in Texas. Bactericera dorsalis completed development on both native Lycium species, albeit with high rates of mortality on L. berlandieri. B. dorsalis acquired and transmitted Lso on L. carolinianum under greenhouse conditions but did not transmit Lso to potato. These results document a previously unknown vector of Lso.

Potential of the mirid bug Engytatus nicotianae, and the parasitic wasp Tamarixia triozae for the biological control of the tomato-potato psyllid; a cage greenhouse assay

ABSTRACT The tomato-potato psyllid (TPP) Bactericera cockerelli is an important pest of several solanaceous crops. The current pest management strategy based on synthetic insecticides is being challenged through the development of pesticide resistance and environmental concerns. This contribution investigates the biological control potential of the mirid bug Engytatus nicotianae, either alone, or in combination with the parasitic wasp T. triozae, for combating the TPP on infested greenhouse tomato plants. In doing so we measured (a) the efficacy of E. nicotianae in reducing TPP numbers on lightly infested plants and (b) the potential for E. nicotianae and T. triozae in combination for effective biological control. In the E. nicotianae only treatment, the predator reduced the number of TPP-infested leaves, but the TPP population reduction was not significant. Conversely, the combined E. nicotianae + T. triozae treatment did show a consistent and significant reduction of TPP-infested leaves as well as TPP populations. These findings suggest that using a combination of the two species might deliver a biological control of TPP under glasshouse conditions. Further research is needed to determine the optimum ratio of E. nicotianae and T. triozae release-densities under different levels of TPP infestation and how this may translate from caged conditions to greenhouse performance. HIGHLIGHTS Engytatus nicotianae alone was not enough for the control of an established TPP population on tomatoes Combined releases of E. nicotianae and Tamarixia triozae markedly reduced the TPP population on caged tomatoes The study's outcome can address some gaps in the biological control of TPP on greenhouse tomatoes.

Identification of three new ‘Candidatus Liberibacter solanacearum’ haplotypes in four psyllid species (Hemiptera: Psylloidea)

Eleven haplotypes of the bacterium, ‘Candidatus Liberibacter solanacearum’, have been identified worldwide, several of which infect important agricultural crops. In the United States, haplotypes A and B are associated with yield and quality losses in potato, tomato, and other crops of the Solanaceae. Both haplotypes are vectored by potato psyllid, Bactericera cockerelli. Recently, a third haplotype, designated F, was identified in southern Oregon potato fields. To identify the vector of this haplotype, psyllids of multiple species were collected from yellow sticky cards placed near potato fields during two growing seasons. Over 2700 specimens were tested for ‘Ca. L. solanacearum’ by polymerase chain reaction. Forty-seven psyllids harbored the bacterium. The infected specimens comprised four psyllid species in two families, Aphalaridae and Triozidae (Hemiptera: Psylloidea). Nucleic acid and/or amino acid sequence analysis of the ‘Ca. L. solanacearum’ 16S ribosomal RNA, 50S ribosomal proteins L10/L12, and outer membrane protein identified three new haplotypes of the bacterium, designated as Aph1, Aph2 and Aph3, including two variants of Aph2 (Aph2a and Aph2b). The impact of these new haplotypes on solanaceous or other crops is not known. The vector of ‘Ca. L. solanacearum’ haplotype F was not detected in this study.

Drought stress affects interactions between potato plants, psyllid vectors, and a bacterial pathogen.

Transmission of insect-borne pathogens is mediated by interactions between insects and plants across variable environments. Water stress, for example, affects the physiology, defense, chemistry, and nutritional balance of plants in ways that alter their tolerance to herbivores and pathogens. However, few studies have explored interactions between water stress and insect-borne pathogens as well as the molecular mechanisms mediating these interactions. Here, we address these knowledge gaps by assessing effects of plant water stress on the transmission of a bacterial pathogen, Candidatus Liberibacter solanacearum (CLs), by the vector Bactericera cockerelli Šulc (potato psyllid). We hypothesized that plant water stress would promote pathogen transmission by inducing plant gene transcripts and phytohormones involved in defense. Our results showed water stress was associated with decreased CLs titer with two psyllid haplotypes. Our analysis of plant gene transcripts suggested water stress affected phytohormone pathways in ways that altered plant tolerance to the CLs pathogen. Our study shows that abiotic stressors like drought may mediate the spread of plant pathogens by altering plant signaling pathways in ways that affect pathogen transmission.

Development and reproduction of a native generalist predator, Coccinella transversalis (Coleoptera: Coccinellidae), on the tomato potato psyllid, Bactericera cockerelli, with a greenhouse assay of biocontrol potential

The tomato potato psyllid (Bactericera cockerelli Šulc (Hemiptera: Triozidae)) can cause significant losses to Solanaceous crop via direct feeding and by transmitting the bacterium Candidatus Liberibacter solanacearum. In the present study, an Australian native ladybird beetle, Coccinella transversalis Fabricius, was examined as a potential biological control agent of B. cockerelli. An age-stage, two sex life table of C. transversalis was constructed, demonstrating that C. transversalis could survive, develop, and reproduce successfully when fed B. cockerelli as a monotypic diet. Predation on B. cockerelli by C. transversalis third and fourth instar larvae and adults fit the Holling 'type II' disc equation. In a glasshouse trial using B. cockerelli-infested tomato plants, C. transversalis larvae reduced the population growth of B. cockerelli larvae by 66% and adults by 59% over one month, reducing loss of leaf chlorophyll and increasing plant biomass relative to controls. The results of the present study were compared with a previous study for the resident ladybird beetle species against B. cockerelli. Whereas C. transversalis suppressed B. cockerelli populations, the impact was less than that of the introduced ladybird, Hippodamia variegata Goeze, which showed higher voracity in previous work. However, B. cockerelli is a suitable prey for C. transversalis and this species should aid in its biological control in agricultural ecosystems in Australia.

Potential of variegated lady beetle Hippodamia variegata in management of invasive tomato potato psyllid Bactericera cockerelli.

The tomato potato psyllid, Bactericera cockerelli (Šulc) is a new invasive pest in Western Australia, which may disperse across the whole of Australia within a few years and cause significant economic losses. Chemical control is the most widely used approach to manage B. cockerelli, but insect resistance, chemical residue and effects on non-target species have become an increasing concerned. Therefore, in this study, the biocontrol potential of variegated lady beetle, Hippodamia variegata (Goeze) was investigated. The impact of utilizing B. cockerelli as a food source on the predator's development and reproduction was assessed by formulating age-stage, two sex life tables. The predatory potential of H. variegata on B. cockerelli nymphs was assessed in a closed arena and the effects of releasing H. variegata for the control of B. cockerelli were then evaluated. H. variegata could successfully develop and oviposit when feeding on B. cockerelli. However, both survival and the rate of development were higher for H. variegata feeding on Myzus persicae (Sulzer) than B. cockerelli or a mixed population of B. cockerelli and M. persicae. A type II functional response was observed for H. variegata. In the greenhouse, the releases of H. variegata larvae reduced the number of B. cockerelli nymphs by up to 66% and adults by up to 59%, which positively influenced the plant chlorophyll content and biomass. This study demonstrated the potential of the resident generalist predator, H. variegata as a biocontrol agent for the invasive pest, B. cockerelli, which may help improving current management strategies. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Symptomatology associated with “Purple top”, an emerging disease of solanaceous fruit species

“Purple top” is an emerging disease that affects solanaceous crops, reported mainly on Solanum tuberosum (potato). Additionally, Bactericera cockerelli has been reported as the insect vector of Candidatus Liberibacter solanacearum (CaLso), a pathogen that has been associated with this disease. However, the information about this disease in Andean fruit species such as Solanum betaceum (tree tomato), S. quitoense (naranjilla) and Physalis peruviana (cape gooseberry) is almost nil. This study was carried out in the Tumbaco Experimental Farm of INIAP to describe the phenotypic symptoms caused by this disease. Molecular diagnosis by PCR method was carried out to diagnose the causal agent associated with the symptomatology. The main symptoms observed were purple color leaves, smaller apical leaves, inward curvature edge leaves, over-sprouting, yellowish and stopped plant growth; however there also were asymptomatic plants. P. peruviana was the most susceptible species because showed 100% of incidence. CaLso was identified as the causal agent associated with this disease. These results contribute to understanding the expression of this disease in Andean fruit crops. However, more studies related to epidemiology, diagnostic methods, mixed infections, vector-pathogen interaction and disease control are required in order to generate information that allows a complete knowledge of this pest.

Survey of Candidatus Liberibacter Solanacearum and Its Associated Vectors in Potato Crop in Spain.

Simple SummaryZebra chip disease (ZC) in potato is an economically important disorder, documented in North and Central America and New Zealand. It is associated with the bacterium ‘Candidatus Liberibacter solanacearum’ (CaLsol), which is transmitted by the psyllid Bactericera cockerelli. The characteristic symptom of ZC is a dark and light striped pattern in chips, making them commercially unacceptable. Naturally CaLsol-infected potato tubers were reported in Europe, where the threat of ZC for European potato crops is a major concern. This work studied the presence and abundance of ZC symptoms and CaLsol in potato plants, as well as those psyllid species that eventually could transmit the bacterium, in the main producing areas in Spain. Very few symptomatic and CaLsol-positive plants were detected in Mainland Spain, and any positive plant was detected in the Canary Islands. Most of the adult psyllids captured were identified as Bactericera nigricornis, and some of them as Bactericera trigonica, but no B. cockerelli was detected. B. nigricornis was found widely distributed in the northern half of the Iberian Peninsula, and it was the only one able to feed and reproduce on potato plants. However, this psyllid does not seem sufficient to pose a threat to potato production, due to the scarce number of specimens and because the frequency of B. nigricornis specimens that were CaLsol+ was very low.‘Candidatus Liberibacter solanacearum’ (CaLsol), the etiological agent of potato zebra chip (ZC), is transmitted to potato plants by the psyllid Bactericera cockerelli (Šulc, 1909) in North and Central America and New Zealand. The risk of the dispersion of ZC in Spain depends on the presence of an efficient vector. This work studies the presence and abundance of ZC symptoms and CaLsol in potato plants, as well as the presence and abundance of psyllid species associated with potato crops in the main producing areas in Spain. Eighty-eight plots were surveyed punctually to detect ZC symptoms and psyllid species in the main potato-producing areas. Furthermore, fourteen potato plots were surveyed by different sampling methods during the cropping season to detect psyllid species from 2016 to 2018. Very few symptomatic and CaLsol-positive plants were detected in Mainland Spain, and any positive plant was detected in the Canary Islands. Most of the adult psyllids captured were identified as Bactericera nigricornis (Foerster, 1848), and some of them as Bactericera trigonica, but no B. cockerelli was detected. B. nigricornis was found widely distributed in the northern half of the Iberian Peninsula; however, this psyllid does not seem sufficient to pose a threat to potato production, due to the scarce number of specimens and because the frequency of B. nigricornis specimens that were CaLsol+ was very low.

Characteristics of environmental RNAi in potato psyllid, Bactericera cockerelli (Sulc) (Hemiptera: Psylloidea: Triozidae).

RNA interference (RNAi) has potential to become a major tool for integrated management of insect pests of agricultural crops based on sequence-specificity and low doses of rapidly biodegradable dsRNA. Deploying 'environmental RNAi' for control of insect vectors of plant pathogens is of increasing interest for combatting emerging plant diseases. Hemipteran insect vectors, including psyllids, are vascular feeders, making their development difficult to control specifically by targeting with pesticidal chemistries. Psyllids transmit "Candidatus Liberibacter solanacearum" the causal organism of potato zebra chip and tomato vein greening diseases, transmitted, respectively, by the potato or tomato psyllid (PoP). Until now, the optimal effective concentration(s) of double-stranded RNA (dsRNA) required for significant gene knockdown and RNAi persistence in PoP have not been determined. The objective of this study was to optimize RNAi in young PoP adults and 3rd instars for screening by oral delivery of dsRNAs. The minimal effective dsRNA concentrations required for robust knockdown and persistence were evaluated by delivering seven concentrations spanning 0.1ng/μL to 500ng/μL over post ingestion-access periods (IAP) ranging from 48h to 12days. The PoP gene candidates evaluated as targets were vacuolar ATPase subunit A, clathrin heavy chain, and non-fermenting protein 7, which were evaluated for knockdown by qPCR amplification. The minimum and/or the second most effective dsRNA concentration resulting in effective levels of gene knockdown was 100ng/μL for all three targets. Higher concentrations did not yield further knockdown, indicating potential RISC saturation at the higher doses. Gene silencing post-IAP of 100ng/μL dsRNA persisted for 3-5days in adults and nymphs, with the PoP 3rd instar, followed by teneral and mature adults, respectively, exhibiting the most robust RNAi-response.

Value‐adding in biosecurity surveillance and monitoring: Testing colour and non‐target semiochemical lures on Psylloidea and Pentatomoidea

AbstractCost efficiency in biosecurity surveillance is vital, and the ability to survey multiple pest species using just one trap is, therefore, highly appealing. The Psylloidea, or plantlice, contain significant horticultural pest species that act as vectors for a number of deleterious plant bacteria. We examine the efficacy of using two different coloured sticky traps, and two semiochemical lures on the general Psylloidea and Pentatomoidea fauna, and a target extant pest psyllid; tomato potato psyllid (TPP) Bactericera cockerelli (Šulc) in Western Australia. Specifically, we test the effect of semiochemical lure (no lure, Asian citrus psyllid ACP lure, brown marmorated stink bug BMSB lure, combined lures), sticky trap colour (yellow‐green vs yellow) and sentinel plant (tomato vs citrus) on psyllid and pentatomid species in 104 urban backyards across Perth, Australia. We found that tomato sentinel host plants and yellow‐green traps significantly increased the capture rate of TPP, but that lures decreased the capture of TPP constraining their use. Yellow‐green traps also increased the capture rate of all other Psylloidea. Although BMSB lures reduced TPP capture, these lures increased the abundances of other Psylloidea and the pest stinkbug Plautia affinis (Dallas) on traps. Thus, our experiment demonstrates that increased efficiencies can be gained with multi‐species traps and semiochemical lures for particular groups, provided that they have been tested on focal organisms in the first instance, as reactions to non‐target lures are unpredictable and species specific.

Tomato Varieties Influence the Performance of Tamarixia triozae (Hymenoptera: Eulophidae) on Bactericera cockerelli (Hemiptera: Triozidae) Nymphs.

Simple SummaryHorticultural crops are often exposed to insect attacks, and insect vectors of plant diseases represent a significant agronomical challenge. The tomato psyllid is a principal vector for bacterial pathogens causing disease and economic losses in crops. In the present study, we evaluated the performance of the parasitoid (T. triozae) against tomato psyllid on tomato varieties. Our results showed that parasitoids selected one commercial variety of tomato plants and attacked the psyllid under greenhouse conditions. We also demonstrated that healthy plants of commercial variety attracted more natural enemies under laboratory conditions. Therefore, these results could help fine-tune the release of natural enemies in greenhouse and field crops.The potato/tomato psyllid Bactericera cockerelli is the Candidatus Liberibacter solanacearum bacterium vector that causes diseases in Solanaceae crops. Pest control is based on synthetic chemical insecticides, plant extracts, and natural enemies such as parasitoids. Tamarixia triozae feeds on nymphs of B. cockerelli, reaching up to 95% parasitism. This work aimed to evaluate the parasitic performance of T. triozae on tomato leaves with B. cockerelli N3 nymphs, using two domesticated (Floradade and Micro-Tom) and one Wild tomato variety. Several assays were completed to identify the parasitoid attraction toward un-infested plants (healthy) and infested plants (damaged) of three varieties. Parasitism preference and “Y” tube olfactometer tests were performed, respectively. The parasitism of Tamarixia triozae showed a preference toward plants of the Floradade variety by 44% compared with the other two varieties (p = 0.0003). T. triozae was more attracted to damaged plants of the Wild variety (p = 0.0523). Healthy plants of Floradade and Micro-Tom varieties attracted a higher proportion of parasitoids, except in the Wild variety, where T. triozae was more attracted to damaged plants. Taken together, the results of this study show that the domestication degree in tomato plants positively influenced the interactions between tomato plants and the parasitoid, T. triozae.

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

Simple SummaryBactericera cockerelli is a pest in different crops including chili, one of the main vegetables worldwide. The presence of this pest in crops causes significant damage to their yield. The control of B. cockerelli is mainly conducted using insecticides, which causes a detrimental effect on the environment and favors the development of resistant pest populations. The identification of pest-resistant plant varieties is the first step towards their future incorporation into management programs. However, chili pepper varieties resistant to B. cockerelli have not been identified. In the present research, different parameters were evaluated in two chili varieties to find out if they are resistant to B. cockerelli. The results obtained showed that B. cockerelli laid fewer eggs in ‘Criollo de Jojutla’ (CJ-2018) compared to the control and that very few eggs managed to reach the adult stage, indicating that CJ-2018 was highly resistant to B. cockerelli. This work constitutes the first step towards the use of CJ-2018-resistant traits for the management of B. 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.

Impacts of zebra chip disease and irrigation on leaf physiological traits in potato

Zebra chip disease (ZC) is caused by the fastidious, phloem-limited, bacterial pathogen ‘Candidatus Liberibacter solanacearum (Lso), which is transmitted from plant to plant by the potato psyllid (Bactericera cockerelli (Sulc)). Understanding how ZC impacts potato (Solanum tuberosum L.) physiology, could help growers in making more informed crop management decisions. Measurements of instantaneous leaf physiological responses, such as photosynthetic CO2 uptake and transpiration on the leaf surface, can be used not only for fast screening of affected plants in the field but also for optimizing irrigation management. Over the 2019 and 2020 field seasons, we characterized time-course photosynthetic physiological responses of potato plants infested by potato psyllids (B. cockerelli (Sulc)) carrying the Lso haplotypes A+B. Potato plants were subjected to different variable-rate irrigation (VRI) treatments (100%, 80%, and 60% of field capacity of the soil) through a center-pivot sprinkler system to examine the impact of the disease on key physiological parameters of photosynthesis and transpiration. Leaf and air temperatures, and hyperspectral profiles of the canopy were also measured and compared. The measurements were made during midday weekly from 25 to 50 days after plant infestation (DAI) with bacteriliferous psyllids. The results showed that many of the measured variables, including stomatal conductance, photosynthesis rate, transpiration rate, quantum yields, and normalized difference in vegetation index started to decrease beginning approximately 28–35 DAI, gradually worsening until 50 DAI, in both 2019 and 2020, as the infection proceeded. The decreases in stomatal conductance in infected plants led to decreases in photosynthesis and transpiration. In turn, reduced transpiration resulted in increased leaf temperature due to decrease in evaporative cooling on the leaf surface. Higher leaf temperatures under hot and dry conditions with high light intensity during the daytime would further reduce photosynthetic light harvesting, which is supported by our data, indicating the damage to the photosynthetic pigment formation and machinery. These findings support the previous report that increased leaf temperature in infected plants may have been derived from the closure of stomata in hypersensitive reactions to infection. These stomatal responses were detected within 28 DAI, a week earlier than the differences in hyperspectral profiles observed 35 DAI, and could be implemented in early disease detection strategiesusing measurements of leaf temperature.

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.

On-farm trials towards reduced insecticides in main crop potatoes in the Waikato Region of New Zealand

Tomato potato psyllid (TPP), Bactericera cockerelli (Sulc) (Hemiptera: Triozidae), is the vector for “Candidatus Liberibacter solanacearum” (CLso), which causes the serious disease “zebra chip” (ZC) of potatoes. Between 2016 and 2019, a reduced-insecticide approach to control TPP was evaluated. We compared a standard-insecticide weekly spray regime that included Integrated Pest Management (IPM)-compatible insecticides plus JMS Stylet Oil® (JMS) as a wetting agent, with a reduced-insecticide regime where we used the oil on its own on alternate weeks with the insecticide/oil mixtures. Spray programme start dates were determined by: (1) crop scouting; (2) sticky-trap monitoring; and (3) degree-day calculation. Crop scouting combined with a sticky-trap action threshold and degree-day data was an effective method for determining when to start spraying. The most substantial reduction in insecticides was achieved by alternating weekly insecticides with the oil formulation on its own. Sub-samples of TPP from sticky traps situated in the trials tested for CLso confirmed the presence of the bacteria in (commonly known as ‘hot’) TPP throughout the trials. The reduced-treatment approach gave statistically similar levels of ZC to the standard insecticide spray programme.

The ecological fitness of the tomato potato psyllid after transferring from non-crop host plants to tomato and potato.

An insect’s fitness varies on different host plant species, and can be affected by previous host feeding experience. In New Zealand, Bactericera cockerelli (the tomato potato psyllid (TPP)) overwinter on various host species, and later migrate to annually grown crop host plants. How changing host plant species affects the insect’s fitness is unknown. This study evaluated if transferring adult TPP from non-crop to crop host species impacts the development and survival of their progeny. TPP were reared on non-crop host species, boxthorn, poroporo, and crop host species, potato and tomato. Adults were transferred from non-crop to the crop host species and allowed to oviposit for 48 hours before being removed. The eggs and nymphs were monitored every 24 hours for the development and survival of each life stage. The incubation period of eggs from adults transferred from poroporo to tomato was 6.9 days, and for boxthorn to tomato was 7.2 days, and was less than for eggs of adults moved from tomato to tomato (9.0 days) and potato to potato (9.2 days) (P < 0.05). Nymph developmental time was similar for all treatments. Total development time (egg to adult) was shorter for the progeny of adults from poroporo transferred to tomato (20.5 days) than those from tomato to tomato (23.2). The survival of eggs did not differ across treatments. Fewer nymphs survived when adults were transferred from tomato to tomato (50.4%) than those from poroporo to tomato (92.1%) (P < 0.05). Total survival (egg to adult) was higher for progeny of adults transferred from poroporo to tomato (80.0%) compared to boxthorn to potato (35.3%), boxthorn to boxthorn (40.7%), poroporo to potato (33.9%) and tomato to tomato (37.6%) (P < 0.05). The implications of this shift in fitness are discussed in relation to TPP management.