Japanese beetle – transforming leaves into lace
This is the latest article in a series on emerging biosecurity risks that growers should have on their radar. These are exotic pests or pathogens that are proving highly invasive around the world.
WHAT IS JAPANESE BEETLE?
Japanese beetle ( Popillia japonica) is a shiny copper and green beetle that spends part of its life cycle above ground and part below ground.
Adults are present above ground and are around 8-11mm long with a width of 5-7mm. The body tends to be metallic green, with contrasting bronze or copper wing covers and five distinctive patches of white hairs down each side of the abdomen.
The adult leaves its feeding host and tends to seek a grassy area nearby when ready to lay eggs. The female burrows into the soil to lay whitish eggs approximately 1.5mm in length, before returning to the surface to resume feeding. The female will burrow and lay multiple times and will deposit around 4060 eggs over her lifetime.
The eggs hatch in to the larval form of the insect, a creamy white grub with a dark head and hairs on the body, which feeds on the plant roots. There are multiple instar stages, the last of which creates an earth cell near the surface for pupation, before finally emerging as an adult. The lifecycle is generally
completed in a year, but can take two years in cooler climates.
WHY IS IT A PROBLEM?
Over 300 plant species are known feeding hosts for Japanese beetle. The larval form of the insect feeds below ground on the roots of grasses, reducing their ability to withstand heat and water stress leading to browning off of leaf material above ground. Turf damage can be particularly apparent on fields and golf courses.
In the United States Japanese beetle is one of the most significant pests for the turf grass and ornamental industries, incurring significant management costs. In contrast adults consume foliage and blooms.The beetle feeds on the upper leaf cells between the leaf veins, resulting in skeletonisation. The holes in the leaf reduce the surface area for photosynthesis, weakening the plant. The different life stages require very different control strategies making effective management complex.
WHAT CROPS DOES IT ATTACK?
The adult Japanese beetle feeds on the leaves of a wide range of ornamental plants such as birch, maples and roses, but also feeds on crops such as apples, asparagus, blackberries, blueberries, corn, grapes, plums, peaches, raspberries, rhubarb and soybeans. The grubs have been known to consume the roots of various vegetable species.
DISTRIBUTION AND SPREAD
The beetle is native to Japan, but has spread to China, Russia, Portugal, Canada and the US. The adult beetles generally fly short distances, so spread primarily occurs through the transportation of infested soil. In Canada efforts are underway to prevent spread of the pest to new areas. Movement of risk goods (all underground plant parts with soil or growing media) is regulated in Canada between regions where the pest is present and those that are pest-free.
Accidental introductions have resulted in the spread of Japanese beetle to new countries, for example it has been suggested that the insect arrived in the US as a stowaway in a shipment of irises. Infested soil is a risk, though NZ has strict biosecurity regulations around soil that minimises the risk of entry via this pathway.
If Japanese beetle were to arrive, it is expected that the abundance of host species and the favourable climate would mean establishment of this pest in New Zealand would be possible.
WHAT TO DO IF YOU SEE IT
If you think you’ve seen Japanese beetle, call the MPI pest and disease hotline on 0800 80 99 66.
In mid-November those involved in biosecurity around the country gathered in Auckland for the one of the biggest events in the 2018 calendar, the Biosecurity New Zealand Forum.
This event, hosted by Biosecurity NZ with forum partners Government Industry Agreement for Biosecurity Readiness and Response (GIA) and the Department of Conservation (DOC), provided an opportunity to both look back and review the past year, and to look ahead to what’s on the horizon in the biosecurity space.
Horticulture NZ was represented at the forum by board members, Barry O’Neil and Bernadine Guilleux and assistant biosecurity manager, Anna Rathé.
The first day saw talks from a broad range of speakers including the Ministry for Primary Industries (MPI), DOC, regional councils, primary sector representatives, universities and business and trade representatives. Many speakers acknowledged that good biosecurity outcomes benefit not only the primary sector, but also NZ’s precious and unique biodiversity.
During the second day of the forum attendees explored different approaches to biosecurity through a series of 10 different workshops. The aim was to translate the inspiration from day one into action. Workshops covered topics such as community, science, kaitiakitanga, technology and risk management. Bernadine Guilleux spoke to the Biosecurity Communication Network about getting biosecurity into the boardroom.
A highlight from the forum was presentation of the annual NZ Biosecurity Awards. These recognise individuals and groups who have made an outstanding contribution to biosecurity in this counry. There were 19 awards finalists in seven categories, all of which were worthy contenders.
Horticulture NZ would like to congratulate all of the finalists and award winners, and thank them for their efforts.
The forum was an excellent opportunity for those involved right across the biosecurity system to come together to celebrate successes, discuss issues, and think collectively about the future of biosecurity in our country. It highlighted the fact that we are all in this together and it was clear that there are many people across the country working incredibly hard to achieve excellent biosecurity outcomes for growers and for wider NZ.
We’ve all got a part to play as we need 4.7 million New Zealanders to actively take part in biosecurity. Growers have a lot at stake and they play an important role in the biosecurity story, particularly on the farm or orchard. We encourage all growers to consider whether proactive biosecurity discussions and procedures are an everyday part of your business. If not, now is the time to start. An active approach to biosecurity will help to protect your assets and wider NZ from the devastating pests and diseases that other countries are grappling with. We have a lot that’s worth fighting for.
“We’ve all got a part to play as we need 4.7 million New Zealanders to actively take part in biosecurity.”