PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Ants
Scientific name
Family Formicidae, Order Hymenoptera. There are
more than 5,000 species of ants in Australia, but
only a few ever damage turf and other plant
materials or are troublesome to humans, eg
Argentine ant (Linepithema humile)
Brown house ant (Doleromyrma darwiniana)
Bull ants, bulldog ants (Myrmecia spp)
Coastal brown ants (Pheidole spp.) .
Funnel ant (Aphaenogaster pythia)
Meat ants (Iridomyrmex spp.)
Fire ant (Solenopsis invicta)
Tropical fire ant (Solenopsis geminata)
See also page 115.
Ants Down Under http://anic.ento.csiro.au/ants/
Australian Ants Online
www.csiro.au/resources/AustralianAntsOnline.html
Host range
Ants are important predators and scavengers; they
contribute to nutrient recycling in soil and soil
structure by constructing nests and burrows. They
rival earthworms in their ability to move soil.
Ants are attracted to the honeydew excreted by
some sap sucking insects, eg aphids, scale.
Edges of leaves and flowers may be eaten.
Some species grow their own fungus for food.
Description & damage
Ants are social insects and live in colonies. The
queen lays all the eggs, is winged at birth but loses
them after mating. There may be more than 1 queen
in a nest. Workers are wingless sterile females
who build the nest and tend the queen, larvae and
pupae and forage for food. Soldiers defend the
colony and often have large heads and mandibles.
Males have wings and mate with the new queens.
Plant damage. Ants may occasionally chew
leaf edges causing minor injury. They can also be a
nuisance when attempts are made to establish
plants through direct seeding. They may nest in
indoor potted plants.
Nests may damage lawns, golf greens,
pastures. Funnel ants (Aphaenogaster spp.)
throw up mounds of earth around entrances to
their nests creating an artificial drought by
removing soil from around roots.
Seedharvesting ants (Pheidole spp.) remove
and destroy seeds.
Honeydew produced by soft scales, aphids,
leafhoppers, lerp insects, mealybugs and whiteflies,
attracts ants which repel predators and parasites of
these pests. Ants may spread young scales to new
hosts. If ant populations are very high, numbers of
soft scales increase dramatically, trees may dieback.
Ants may nest in and around houses
paths, paved areas, pots and invade houses,
compost heaps, mulched garden beds and
uncultivated land, lawns, school yards, parks.
Ants can also block micro-sprinklers in orchards.
A few species will occasionally attack electrical
wiring and extensive damage has occurred.
Some ants infest timber damaged by fungi,
termites or borers in retaining walls, fences and
buildings. None of the ant species present in
Australia damages timber in good condition.
Environmental threat, eg
– Stings of some species need medical attention.
Ants may irritate pickers in orchards.
– Threaten outdoor activities, eg barbecues.
– Fire ants (Solenopsis invicta) are a public
nuisance and pest of agriculture and horticulture. If
the nest is disturbed they will aggressively and
repeatedly sting humans and pets. Fire ants are
predators of root weevil larvae in citrus orchards.
– Bigheaded African ants (Pheidole magacephala)
are a major threat to Kakadu National Park.
– Crazy ants (Anoplolepsis gracilipes) swarm all
over, poison and eat slow moving red land crabs or
young birds in nests on Christmas Island. Mainly
an environmental pest but can be a minor
agricultural pest in Christmas Island, NT and Qld.
– Ant communities in any area may provide an
indication of the level of disturbance of an area.
– Overseas some species are known to carry diseases
and can pose a threat in hospitals and veterinary
clinics. Uncommon in Australia where in general
ants are mainly a nuisance pest.
Diagnostics.
Ants are easily recognized due to their ‘wasp
waists’ and elbowed antennae.
Distinguishing one ant species from another may
requires the help of an ant specialist or you can
access online keys (see above).
Fig. 89. Ants (Family Formicidae).
Fig. 90. Argentine ant
(Linepithema humile). PhotoNSW
Dept of Industry and Investment (E.H.Zeck).
All enlarged x16
1. Eggs
2. Fully-fed legless larva
3.Pupa of male showing
developing wing buds
4.Worker ants about 3 mm long
5. Queen after wings have
broken off
Insects and allied pests - Hymenoptera (ants, bees, sawflies, wasps) 119