PestFacts November 2021
Cotton tipworm moth reported in wheat
Cotton tipworm moth (Crucisoema plebejana) has been reported at Booleroo Centre feeding inside the grain of wheat heads near a gate and fencing. The caterpillars were producing webbing and frass. Similar caterpillars and symptoms have also been reported at Booborowie.
Cotton tipworm caterpillars are 5 – 12 mm long, cream coloured (sometimes tinged pink) with a dark brown head.
They are a cosmopolitan species, typically found in tropical and subtropical areas but are known from records across Australia, including inland.
They feed on the immature seed capsules of Malvaceae but can be a cotton pest in Queensland. They very rarely feed on wheat.
We only found one record of cotton tipworm moth feeding on wheat in the Waite Insect and Nematode Collection (WINC), which was from Gladstone in 1983. This suggests it’s a very infrequent issue.
How to report
PestFacts SA always wants to know what pests you are finding in your crops and pastures, whether it is the ‘usual’ pests, beneficial or unknown. Reports of not seeing anything are valuable too! Send your reports or identification requests via the PestFacts Map online report form.
Alternatively, please contact:
Rebecca Hamdorf
Phone: 0429 547 413
Email: rebecca.hamdorf@sa.gov.au
Maarten van Helden
Phone: 0481 544 429
Email: maarten.vanhelden@sa.gov.au
Spring means aphids on the move
As part of the iMapPESTS project, we are recording aphid captures at Giles Corner Riverton (just north of Tarlee) in the high suction trap. During the second half of October, we’ve observed flights of many of the grains aphids:
These reports are expected as crops and grasses start to ripen and become less attractive, which causes aphids to migrate as temperatures rise in spring.
For data, visit the iMapPESTS Giles Corner trial dashboard.
Migration unlikely to cause yield loss
Migrating aphids are not attracted to remaining crops and won’t build up to damaging levels.
Migrating RWA can cause light symptoms on the flag leaf by making test probes but this will not cause any issues for yield.
In the right conditions, the oat aphid and corn aphid can transmit viruses but even if they did, yield loss will not occur in cereals infested at this developmental stage .
All these aphids will be looking for summer host plants. They especially prefer younger plants. If you have recently cut hay, it’s likely these aphids will get into the regrowth. So, keep an eye open for aphids on these plants. RWA is especially easy to spot on regrowth.
Outlook for next autumn
The survival of host plants over summer will be the deciding factor for how many of these aphids will be present in the next autumn when new crops go in.
Results from the GRDC project ‘Russian Wheat Aphid Risk Assessment and Regional Thresholds’ showed that barley grass germinating early in February can potentially increase RWA risks for autumn crops (Van Helden et al 2021).
Controlling weeds and volunteer crops (the ‘green bridge’) before you begin sowing will help limit populations of aphids and other soft-bodied pests and disease. For more information on managing the green bridge, see the GRDC Green Bridge Factsheet.
References
M Van Helden, T Heddle, C Proctor, L Alhwash, B Wake, F Al-Jawahiri. 2021. Noncrop Host Plant Associations for Oversummering of Diuraphis noxia in the State of South Australia. Journal of Economic Entomology, 2021 https://doi.org/10.1093/jee/toab191
Armyworm head showing three white stripes on cervical shield (neck).
Photo: R. Hamdorf
Keep an eye out for faba bean aphid
The exotic faba bean aphid (FBA, Megoura crassicauda) was originally detected in a suburban backyard in Sydney in October 2016, and then on faba bean crops at Tamworth and Breeza in northern New South Wales (NSW) in October 2017. It was determined to be infeasible to eradicate.
Very few faba beans were sown in northern NSW during 2018 and 2019, but when seasonal conditions improved FBA was detected in Grafton in July 2020. Later in 2020, it was found in north-western NSW on faba beans and woolly pod vetch. Several more samples were collected from private gardens in south-eastern NSW and Sydney.
This spring, as reported by The Beatsheet in their latest article ‘Keep an eye out for faba bean aphid, particularly during spring’ FBA has been detected at Tamworth, Breeza on faba beans and vetch. FBA was also recently found on broad beans in an Ipswich backyard.
Biology and potential impact
There is limited information on the biology of this aphid in field conditions. Hosts for FBA include Fabaceae (legumes) within the genera Lathyrus and particularly Vicia, which includes:
- faba beans
- broad beans
- vetch.
The NSW Department of Primary Industry’s experience suggests that, so far in NSW, FBA has a preference for faba beans and vetches, followed by common pea and lentils. Lucerne, subclover and legume weeds support somewhat limited reproduction and survival for FBA and can persist as alternative hosts all year round.
What FBA looks like
FBA are large aphids thatcan coexist on leguminous plants with the pea aphid (PDF) (Acyrthosiphon pisum) and the cowpea aphid (PDF)(Aphis craccivora) but are readily identifiable by:
- aphid up to 2.5-3mm in length
- dark green spindle-shaped body with long legs and antennae
- black head, pro-thorax, antennae, leg, siphunculi (`exhaust pipes`) and cauda (`tail`)
- red eyes
- large tubercles (structure at the base of antennae) that face outwards when viewed from above
- slightly swollen siphunculi.
Biosecurity and reporting
So far, the aphid has not been detected in South Australia but the potential for it to spread is currently unknown. Growers and agronomists are encouraged to implement and maintain good on-farm biosecurity measures and be vigilant for signs of unusual pest or disease symptoms in their crops.
Suspect observations should be reported via the Exotic Plant Pest Hotline on 1800 084 881.
References
Blackman, R. L., & Eastop, V. F. (2000). Aphids on the world's crops: an identification and information guide (No. Ed. 2). John Wiley & Sons Ltd.
Hales, D. F., Gillespie, P. S., Wade, S., & Dominiak, B. C. (2017). First detection of 'Megoura crassicauda' Maudvilko (Hemiptera: Aphididae) in Australia and a review of its biology. General and Applied Entomology: The Journal of the Entomological Society of New South Wales, 45, 77.
Redlegged earth mite survey
Cesar Australia is conducting a national survey on redlegged earth mite (PDF) (RLEM, Halotydeus destructor). Your responses will help increase understanding of current control strategies and to improve how the redlegged earth mite is managed across Australia. It only takes 10 minutes.
To thank you for your time, all survey participants will be given early access to module one of Cesar Australia’s redlegged earth mite online training which covers identification, distribution, host range and damage.
The survey is being led by Cesar Australia as part of a GRDC investment (CES2010-001RTX), which has been extended to:
- red meat producers through co-investment from Meat and Livestock Australia
- pasture seed producers through co-investment from AgriFutures Pasture Seeds Program (PRJ-013101).
The wider project involves contributions from the Department of Primary Industries and Regional Development (DPIRD), the University of Melbourne, and CSIRO.
If you have any questions, please contact Dr Lizzy Lowe from Cesar Australia: llowe@cesaraustralia.com
