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.

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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.

LO­CAL RISK

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.”

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