Bagrada, the un­wel­come cousin

There are a num­ber of emerg­ing biose­cu­rity risks that growers should have on their radar as th­ese are ex­otic pests or pathogens that are prov­ing highly in­va­sive around the world.

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WHAT IS BAGRADA BUG?

The bagrada bug Bagrada hi­laris (Burmeis­ter), also known as the painted bug, is a true bug of the or­der Hemiptera and in the same stink bug fam­ily (Pe­nato­mi­dae) as the brown mar­morated stink bug (BMSB).The bagrada bug has a shield-shaped body and ranges in size from 5-7mm long and 3-4mm wide, with fe­males slightly larger than males.

Adult bugs are black with red and yel­low mark­ings that run length­wise down the cen­tre and edges of its body. Bugs are most ac­tive dur­ing spring and sum­mer and like BMSB it ag­gre­gates and over­win­ters in the adult stage. When en­vi­ron­men­tal con­di­tions are favourable (for ex­am­ple tem­per­a­tures above 25°C and be­low 41°C) and food sources are plen­ti­ful, mul­ti­ple gen­er­a­tions can oc­cur in a sea­son. Fe­males lay on av­er­age 100-200 eggs sin­gu­larly or close to­gether in lin­ear clus­ters of up to 10 eggs in loose soil, on the un­der­side of leaves and on stems.

WHY IS IT A PROB­LEM?

Like BMSB, bagrada bug is ex­pand­ing its dis­tri­bu­tion and is pos­ing a threat to veg­etable crops in its in­vaded ter­ri­tory. It threat­ens hor­ti­cul­ture, ur­ban en­vi­ron­ments and causes sooty mould prob­lems on plants and hard sur­faces.

It’s a phloem feeder, us­ing its suck­ing mouth parts to feed and lac­er­at­ing tis­sue dur­ing the process. The in­sect prefers young plant ma­te­rial, in­clud­ing new leaves and the api­cal meris­tem. Feed­ing dam­age causes cir­cu­lar scorch­ing and leaf mal­for­ma­tion that leads to wilt­ing, des­ic­ca­tion and tis­sue death and can re­sult in plant col­lapse. Bar­gada bugs of­ten form large ag­gre­ga­tions of adults and nymphs when feed­ing, char­ac­ter­is­tic of the species.

WHAT CROPS DOES IT AT­TACK?

The main hosts of bagrada bug are bras­sica species in­clud­ing broc­coli, cau­li­flower, kale, turnip and Asian greens. How­ever the bug is also been known to in­fest grasses, potato, cot­ton, corn, pa­paya, rock­melon, wheat and legumes. It is prob­a­ble that the host range could con­tinue to ex­pand, with bagrada bugs of­ten seen ag­gre­gat­ing and at­tempt­ing to feed on plants that are non-hosts.

DIS­TRI­BU­TION AND SPREAD

Na­tive to Africa, bagrada bugs are found through south­ern and eastern Africa, as well as Asia and parts of south Europe. Most re­cently in 2009, bagrada bug in­vaded the United States, start­ing from the eastern coast in Cal­i­for­nia and mov­ing into Ari­zona, Ne­vada, Utah, New Mex­ico and Texas. It’s of­ten de­tected on plant ma­te­rial trav­el­ling across state bor­ders.

RISK TO NEW ZEALAND

Bagrada bug is cur­rently found in tem­per­ate and sub­trop­i­cal en­vi­ron­ments associated with a range of host plants. Un­like BMSB which over­win­ters in struc­tures, bagrada bug over­win­ters in ar­eas where its pre­ferred host plants, bras­si­cas, are present. It may be pos­si­ble for bagrada bug to es­tab­lish in ar­eas of New Zealand that ex­pe­ri­ence sum­mer tem­per­a­tures ap­pro­pri­ate for the bugs life­cy­cle, such as Auck­land and North­land.

WHAT TO DO IF YOU SEE IT

If you think you’ve seen bagrada bug, call the Min­istry for Pri­mary In­dus­tries pest and dis­ease hot­line on 0800 80 99 66.

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