PestFacts 14 August 2023
Liming and snails
We regularly receive reports of increased numbers of pest snails in paddocks after liming. This often raises questions about machinery moving snails or snail eggs with the lime. While this cannot be ruled out in some instances, it is more likely that existing snail populations in the paddocks benefit from increased access to calcium.
Why calcium is beneficial to snails
Mollusc shells are made of calcium carbonate. They are formed by discharge of proteins as scaffolding and then calcium as the main component of the shell. Availability of calcium for snails increases growth capability and the strength of their shells.
Calcium is also beneficial to snails’ reproductive output. Research has shown that addition of lime to soil increases production of juvenile snails – see Determining the effect of lime on small pointed (conical) snail fecundity and shell strength.
Snail management
When considering liming paddocks consider how this may increase the current snail population. Ideally, you should also budget for baiting paddocks after liming.
Understanding the biology of pest snails and how they respond to cultural activities on the farm is key to managing them effectively. The new Nail the Snails guide is available to help you with practical integrated snail management.
Brown pasture looper on medic
Brown pasture looper (Ciampa arietaria) caterpillars have been reported feeding in a pasture paddock west of Roseworthy. Within the pasture the caterpillars were favouring the medic.
Identifying brown pasture looper
Brown pasture looper caterpillars grow up to 20 to 35 mm in length, are coloured dark brown to grey and have a distinctive wavy yellow line along the back on either side of an obvious dark band. They also have red colouration on the sides around their breathing holes (spiracles).
They use their single pair of abdominal prolegs and one pair of anal prolegs to move using a series of back arches, which results in a characteristic looping motion. Similar looking caterpillars include native budworm and pasture day moth caterpillars, but these have four pairs of abdominal prolegs.
Brown pasture looper management
Monitor the edges of crops and around patches of capeweed, as brown pasture looper is most prevalent there. Often movement of brown pasture looper occurs when the broadleaf weeds they are feeding on are killed with herbicide.
Several beneficial insects will feed on brown pasture looper including egg parasitoid wasps and predatory shield bugs. Brown pasture looper only has one generation per year.
If chemical control is warranted, spot or perimeter spraying with one of the several insecticides registered for this pest will usually suffice.
Source of reports: Chris Butler (Roseworthy Rural Supplies)
Cowpea aphid on lupins
Cowpea aphids have been reported on lupins near Kimba.
Identifying cowpea aphid
Adult cowpea aphids are shiny black in colour and nymphs are dull grey as they are lightly dusted with wax. All stages have white and black legs. Cowpea aphid can reach up to 2 mm in length.
Cowpea aphids tend to colonise single plants before moving onto surrounding plants to create 'hot spots' within a crop.
Cowpea aphid management
Cowpea aphids are most prominent in spring but are also active during autumn and can persist through winter. The key time to monitor vulnerable crops is during bud formation to late flowering.
There are many effective natural enemies of aphids, including ladybeetles, hoverflies, damsel bugs, lacewings and parasitoid wasps. Naturally occurring aphid fungal diseases can also suppress aphid populations. When monitoring for aphids also keep an eye on the beneficials as they play a very important role in supressing aphids. If levels of parasitism and predation are increasing over time, it is likely that aphid populations will be controlled naturally.
If chemical control is warranted check the Australian Pesticides and Veterinary Medicines Authority's Public chemical registration information system search for chemical options. Spot spraying may be sufficient. Try to avoid the use of broad-spectrum insurance sprays and apply insecticides only after monitoring and distinguishing between aphid species.
Helicoverpa trapping network
The SARDI Entomology Helicoverpa moth trap network is currently being organised to help identify when Helicoverpa flights occur this spring. Understanding the timing of moth flights can provide:
- early warning of potential caterpillar activity in crops
- insight on when to monitor for target size caterpillars.
Flights of native budworm moths are not an indication that control is needed in paddock. Early sprays based on moth flight numbers alone will not be beneficial as target size caterpillars won’t be in the paddock and won’t be controlled. Always monitor actual insect pressure before deciding on management.
At each location, we are separately trapping the two common Helicoverpa species:
- native budworm (H. punctigera)
- corn earworm (H. armigera)
Once the network is finalised and set up, we will provide weekly updates of moth trapping data during spring – watch the PestFacts Twitter for updates.
Being a part of our trapping network includes setting up two pheromone bucket traps and monitoring the numbers of moths caught inside the traps weekly. If you would like to be part of the trapping network or would like more information, please email Rebecca Hamdorf: rebecca.hamdorf@sa.gov.au.
Beneficials toxicity guide
Healthy populations of beneficial insects can suppress pest numbers, but it has not always been clear how other management strategies, particularly insecticide use, affects them. As part of the Australian Grains Pest Innovation Program there is now a guide for grain growers and advisers in the Beneficials chemical toxicity table.
This table summarises the impact of various insecticidal and miticidal active ingredients on a range of beneficial insects. Chemicals have been ordered from least to most toxic.
The Beneficials chemical toxicity table can help inform growers and advisers to make targeted spray decisions that minimise harm to beneficial insects and maximise biological control for pests.
Further information on beneficials and IPM strategies:
How you can help current research
The Australian Grains Pest Innovation Program aims to develop high impact, sustainable, and scientifically-tested pest management options. The team is actively studying the manipulation of endosymbionts (organisms that live in the body of another to the benefit of both). These tiny organisms living within insects can influence virus transmission, minimise direct feeding damage caused by aphids, and increase rates of parasitism and predation by beneficials on key crop pests.
To support research efforts, you can provide the research team with specimens. Specifically, the team is interested in obtaining samples of:
- red-legged earth mite (Halotydeus destructor)
- potato aphid (Macrosiphum euphorbiae)
- green peach aphid (Myzus persicae)
- blue green aphid (Acyrthosiphon kondoi)
- oat aphid (Rhopalosiphum padi)
- Russian wheat aphid (Diuraphis noxia)
- pea aphid (Acyrthosiphon pisum)
- faba-bean aphid (Megoura crassicauda)
- cabbage white (Pieris rapae) and the parasitoids Cotesia rubecula and C. glomerata
- diamondback moth (Plutella xylostella) and the parasitoid Diadegma semiclausum
- corn earworm (Helicoverpa armigera) and the parasitoid Netelia producta
- light brown apple moth and the parasitoid Dolichogenidea tasmanica
Simply pack the live samples into a non-crushable plastic container with some host plant and paper towels, and send via express post to:
Cesar Australia
Att: Lilia Jenkins and Sam Ward
Level 1, 95 Albert Street
Brunswick VIC 3056
For detailed guidelines on sample collection and postage, please see Collecting and sending invertebrate samples or email Lilia Jenkins: ljenkins@cesaraustralia.com.
For more information, see The Australian Grains Pest Innovation Program (AGPIP).
The latest information for growers and advisors on the activity and management of pests in all broadacre crops during the winter growing season.
