Insects of Southern Australian Broadacre Farming Systems - Grains ...
Insects of Southern Australian Broadacre Farming Systems - Grains ...
Insects of Southern Australian Broadacre Farming Systems - Grains ...
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Confused with/similar to<br />
These two closely-related species are difficult to identify<br />
without specialist knowledge.<br />
The brown ‘flax-seed’ pupae can be diagnostic in the<br />
field. The presence <strong>of</strong> a gall produced by M. hordei is also<br />
characteristic.<br />
Larvae can be confused with other legless maggots<br />
but there are no major fly larvae pests above ground on<br />
plants in broadacre crops in southern Australia.<br />
Adults can also be confused with other midges and<br />
mosquitoes.<br />
Distribution and potential spread<br />
Hessian fly is widespread in Europe and has been<br />
recorded in the USA. It has also been detected in other<br />
countries including New Zealand, Africa and Russia.<br />
Barley stem gall midge has been recorded in Europe,<br />
USA, Canada and Africa.<br />
These species actively fly and can disperse on wind<br />
currents more than nine kilometres. All life stages<br />
(larvae, pupae and adults) can achieve long distance<br />
dispersal by hitchhiking on plant material (e.g. straw).<br />
Pupae are able to survive over long periods.<br />
Crops attacked/host range<br />
These exotic fly pests impact on market access and<br />
production costs. Crop losses <strong>of</strong> up to 40% have been<br />
recorded for Hessian fly.<br />
Hessian fly: Wheat is the primary host capable <strong>of</strong><br />
supporting the whole lifecycle. Alternate host plants<br />
include wheatgrass, rye, barley, grass weed species and<br />
broome.<br />
Barley stem gall midge: Found almost exclusively on<br />
barley but occasionally recorded on oat, wheat and rye.<br />
Due to the difficulty in distinguishing between these<br />
two species, the information on distribution and<br />
host types are limited and not absolute.<br />
Damage symptoms<br />
Hessian fly larvae feed on leaves, stems and plant heads<br />
resulting in leaf discolouration (dark green to bluishgreen),<br />
stunted growth and reduced grain quality and<br />
yield. Larvae lodge themselves between leaf sheaths<br />
above nodes, while pupae are found at the base <strong>of</strong> plants<br />
at harvest. Control <strong>of</strong> these flies would rely on cultural<br />
methods and plant host resistance as most chemical<br />
controls are ineffective.<br />
Barley stem gall midge larvae feed at the base <strong>of</strong> barley<br />
between the leaf sheath and the stem, producing small<br />
characteristic pea-shaped galls. Galls are an abnormal<br />
outgrowth <strong>of</strong> the plant in response to barley stem<br />
gall midge feeding. Infestations can lead to weakened<br />
stems, stunted plant growth and a loss <strong>of</strong> grain quality<br />
and yield. Infested plants are a darker green than<br />
undamaged plants.<br />
The adults do not feed. There may be 2-3 generations<br />
each year.<br />
Surveillance<br />
On a symptomatic plant, separate the sheath at the base<br />
<strong>of</strong> the stem. You may find maggot-like larva feeding on<br />
the stem surface. Look carefully for a pea-shaped gall<br />
formation caused by Barley stem gall midge. Carefully<br />
split the gall and you may find the larvae inside.<br />
Early detection <strong>of</strong> plant pests can greatly increase<br />
the chance <strong>of</strong> successful eradication and reduce the<br />
cost and social impact <strong>of</strong> an incursion.<br />
Incorporate surveillance for exotic pests when<br />
undertaking routine crop monitoring and other crop<br />
detection and measurement activities.<br />
Any insect that resembles these flies must be sent to a<br />
specialist for identification.<br />
Reporting protocol<br />
A rapid response to detection <strong>of</strong> potential exotic<br />
pests can be the key to containment, eradication or<br />
management. If you see anything unusual, call the Exotic<br />
Plant Pest Hotline on 1800 084 881.<br />
Speak to your department <strong>of</strong> primary industries or<br />
department <strong>of</strong> agriculture before sending any samples.<br />
It is essential that the correct sampling protocol is<br />
followed including packaging, handling and transport to<br />
the laboratory assigned for diagnosis. Incorrect handling<br />
could spread the pest further or render the samples unfit<br />
for identification.<br />
Stop the movement <strong>of</strong> people, vehicles and equipment<br />
in the detected area until a confirmation can be made.<br />
More information<br />
Plant Health Australia website<br />
www.planthealthaustralia.com.au/biosecurity/grains<br />
Ute Guides, <strong>Southern</strong> (pp. 169, 170, 175)/Western (pp. 136, 137, 142).<br />
SECTION 4 COMMON Pest, Beneficial AND EXOTIC Species<br />
53<br />
<strong>Insects</strong> <strong>of</strong> <strong>Southern</strong> <strong>Australian</strong> <strong>Broadacre</strong> <strong>Farming</strong> <strong>Systems</strong> Identification Manual and Education Resource © 2012
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