Tomato potato psyllid

Tomato potato psyllid

21 June, 2016

Just over 2,000 kilometres separates New Zealand from the east coast of Australia and the potential of a tomato potato psyllid (Bactericera cockerelli) incursion* from our neighbour is of serious concern to Australian horticulture, particularly the potato industry.

The tomato potato psyllid (TPP) is a tiny sap-sucking insect that feeds on tomato, potato, capsicum, chilli and nightshade plants. During 2012-13 the value of the Australian potato, capsicum and tomato industries were collectively valued at approximately $AUD 1.2 billion (ABARES 2012-13). The psyllid wreaks havoc on crops causing stunting, distorted and discoloured leaves and stem death.

This tiny insect is also a natural vector for the Zebra chip pathogen, the bacterium Candidatus Liberibacter solanacearum. Zebra chip in potatoes results in significant yield losses, a mottle to stripe pattern of light/dark regions, as well as stunted growth. It also stops the production of fruit in tomato crops. In 2010 the cost to New Zealand was NZ$50 M per annum in crop losses and NZ$12 M in agrichemicals.

*Update note: In February 2017 tomato potato psyllid was detected in Western Australia for the first time, prompting a national biosecurity response. It had not previously been found in Australia.


Global reports of Zebra chip

  • Symptoms first reported from near Saltillo, Mexico in 1994

  • First noted in Lower Rio Grande Valley/ Pearsall, Texas in early 2000s

  • By 2006, disease had spread to most potato production areas of Texas, Kansas, Arizona, Colorado, Nevada, New Mexico and California

  • 2008 reported in New Zealand

  • 2012 reported from Idaho, Oregon and Washington State

  • 2014 tomato potato psyllid reported on Norfolk Island

 

(Pictured right: Symptoms of zebra chip in fried potato.)


TPP is now established in many states in the USA and Canada. In 2006 it was discovered in New Zealand and has now spread throughout growing areas in the North and South Islands. Analysis of the entry of the psyllid into New Zealand concluded the insect ‘…was most plausibly introduced to New Zealand as a result of smuggling, rather than through slippage on regulated pathways’ (Thomas et al, 2011). Current control options involve using insecticides at planting and during cropping. The associated control costs to industry should this pest become established are significant.


"The TPP is a major pest in the countries where it is established, causing yield loss, and crop rejection from buyers. Growers also face much higher pesticide costs attempting to limit the extent of TPP damage. The costs to the New Zealand potato industry are estimated to vary between NZ$28-62 million per year, depending on the source. According to the Potato Industry Biosecurity Plan the overall risk from the TPP is high and, when combined with Zebra chip, the risk profile increases to extreme. It is the only potential threat to achieve that level of risk profile.

The costs to Australia, if it was unable to be eradicated, could potentially be in the hundreds of millions per year. The TPP’s harm is not restricted to potatoes, it has caused massive losses in the capsicum, eggplant and tomato industries. There is much to learn from overseas experiences and, if properly captured and extended, great improvements in preparedness and eventual response, could be obtained."

Dr Jessica Lye, National Manager – Scientific Affairs, AUSVEG

Photo: Tomato potato psyllid Copyright © The New Zealand Institute for Plant and Food Research Limited. All rights reserved.

The arrival of tomato potato psyllid (TPP) on Australian shores has the potential to threaten the viability of potato production in this country. The onset of TPP would not only devastate paddock and factory yields - but critically - it’s management would result in the destruction of biological control for a range of other significant potato pests. The processors of potatoes have led the way in establishing surveillance for TPP in Australia and readily welcome research and extension initiatives that may allay the threat or its potential impact.

Anne Ramsay, Potato Processing Association of Australia (PPAA)


Tomato potato psyllid research

PBCRC research is enhancing Australia’s preparedness against the potentially devastating impacts of TPP and Candidatus Liberibacter solanacearum through improving our knowledge, diagnostics capability and informing more targeted surveillance to help with early detection. The research is also supporting New Zealand in their on-going battle.

PBCRC scientific research on the tomato potato psyllid includes the following projects:

Understanding the role of alternative host plants in tomato potato psyllid and Liberibacter life cycle and ecology

Tomato, potato and capsicum are known to be tomato potato psyllid’s (Bactericera cockerelli; TPP) preferred crop hosts however there is limited knowledge of non-crop hosts. This project is gathering knowledge on TPP and Candidatus Liberibacter solanacearum interactions with the non-crop host plants. It also developed a scientifically validated list of New Zealand and Australian TPP and Candidatus Liberibacter solanacearum crop and non-crop host plants that could potentially serve as overwintering, breeding and feeding sites or reservoirs.

New approaches for diagnosing bacterial pathovars

This project has validated the application of emerging technologies to the development of detection and diagnostic tools of biosecurity value. This research has contributed to understanding the genetic diversity in Candidatus Liberibacter solanacearum and developed new assays to detect the bacterium in the psyllid vector and plants. The current focus of this research is developing in-field diagnostic assays for the bacterium to assist in surveillance and faster responses to potential findings.

Enhanced surveillance strategies in horticultural industries based on knowledge of natural dispersal pathways

It has been found that there are natural dispersal pathways for insects to enter Australia from New Zealand. Building on these findings, this project is working to improve our biosecurity surveillance strategy through providing information on what, where and when winds are most likely to bring them into Australia from the north and from New Zealand. These strategies will be incorporated into industry biosecurity plans and mitigation activities, helping to strengthen biosecurity for our horticulture industries.

Psyllid microflora - Implications for Liberibacter disease surveillance and pest control (PhD: Jacqueline Morris)

Ensuring that diagnostics are accurate is important to ensure valid diagnosis – an invalid result could cause trade disruptions and loss of exports. Both Zebra chip and citrus greening disease are caused by Candidatus Liberibacter and vectored by psyllid species that are not present in Australia. However, Australia is a centre of psyllid diversity with hundreds of species present. This project will be the first to research the microflora of the native Australian eggplant psyllid (Acizzia solanicola) and will aid validation of diagnostic protocols for the detection of Ca. Liberibacter in Australia.

Psyllid phylogenetic and endosymbiont associations in New Zealand and Australia (PhD: Francesco Martoni)

Exotic psyllids, such as TPP and the Asian citrus (Diaphorina citri) psyllids, as well as the native Australian eggplant psyllid (Acizzia solanicola), represent an imminent threat to the Australian horticulture industry through impact on crop yields. This project is providing a better understanding of the psyllid species and endosymbiotic microbe associations already in New Zealand and South-East Australia. It will also enable a better understanding of the relationship between a psyllid, the host plant and its microflora.

Candidatus Liberibacter solanacearum on Norfolk Island (small initiative project)

In 2014 the Australian Federal and Norfolk Island governments coordinated a major quarantine survey. During the survey the tomato-potato psyllid (Bactericera cockerelli) and the bacterium Candidatus Liberibacter solanacearum was found. Norfolk Island is 1,400 kilometres east of mainland Australia and there are strict quarantine measures in place for movement of goods between Norfolk Island and the mainland. This project aimed to determine the distribution of Candidatus Liberibacter solanacearum, which plant species the psyllids have been feeding on and to gather samples for further analysis. The project will facilitate management practices to reduce the threat of and enhance preparedness for an incursion to mainland Australia. The pathway of entry to Norfolk Island is unknown at this stage.


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