Monitoring your pulses shouldn’t be overlooked this season
Cowpea aphid has been observed in southern NSW lucerne and vetch paddocks, and their incidence is a timely reminder about possible faba bean aphid presence this season.
In this article we’ll cover where these aphids have been reported, why cowpea aphid can be a cause for concern and why we want you to keep an eye out for the faba bean aphid.
Large cowpea aphid colonies in some paddocks
Reports of cowpea aphid (Aphis craccivora) in lucerne around the Ariah Park region of the NSW central west slopes and plains in Mid-May, having been discovered in vetches as well in the same region a week later. Many plants in some paddocks are hosting the aphid.
There have been multiple reports of concern arising around livestock grazing in infested paddocks. High infestation levels and feeding damage have occurred in ungrazed lucerne paddocks in Urana in the NSW Riverina region.
Out-of-character occurrences of cowpea aphid on canola in the Victorian Mallee have also been reported. This is atypical behaviour for the pulse pest, as they have been known to occasionally colonise brassica plants, but not usually canola.
This last month also saw a faba bean aphid (Megoura crassicauda) infestation in a broad bean crop just north of the Victorian border near Albury, an early occurrence of this novel pest. Last year, the faba bean aphid was out in numbers from the end of winter through to spring across both NSW and VIC.
Telling the difference between cowpea aphid and faba bean aphid
Cowpea aphid and faba bean aphid have similar crop hosts, favouring legume and pulse crops. The cowpea aphid’s hosts include field peas, lupins, lentils, faba beans, lucerne, clover and medics, while the faba bean aphid prefers faba beans and vetches.
They also both tend to colonise densely on the stems of plants – though they are distinctly different in colour.
The cowpea aphid is black or dark grey, while the faba bean aphid is dark green, with a black head, cauda, siphunculi, antennae, and legs.
Legume and pulse crops can also host other aphids, including pea aphid, bluegreen aphid and sometimes green peach aphid. Their predominately lighter green colour profiles of these species means they are unlikely to be confused with cowpea aphid or faba bean aphid.
Implications of cowpea infestations
Cowpea aphid has been implicated in photosensitisation in livestock that have grazed on infested plants; take heed and keep an eye out for this pest. If you are concerned about photosensitisation of livestock feeding on cowpea aphid infested crops and pastures, please seek veterinary assistance.
Cowpea aphid can cause direct feeding damage to infested plants when in high numbers. Symptoms include plant discolouration, bunching and wilting of leaves, and stem twisting.
Cowpea aphid can also cause indirect damage by spreading plant viruses including cucumber mosaic virus (CMV), bean yellow mosaic virus (BYMV), alfalfa mosaic virus (AMV) and pea seed-borne mosaic virus (PsbMV).
For more information on cowpea aphid management visit our PestNote.
Keep an eye out for faba bean aphid
The faba bean aphid is a relatively new aphid in south-eastern crops and we are unsure what their presence means for pulse and legume production in our region.
Research from NSW DPI in the northern region has shown the faba bean aphid can carry and transmit the bean leaf roll mosaic virus (BLRV) and Pea seed-borne mosaic virus (PsbMV). Intensive infestations can cause necrosis, wilting, stunting and defoliation from direct feeding, though the extent of their potential damage and the economic implications of said damage are still unknown.
At Cesar, we’re undertaking a new project to determine the impact of faba bean aphid on faba bean and vetch production in south-eastern Australia. We’ll be conducting field surveillance and subsequent laboratory studies throughout the emergence and finishing stages of host crops to determine their distribution, confirm the efficacy of registered pesticides and identify potential new selective pesticides to inform the development of IPM strategies for this pest.
If you spot faba bean aphid in southern NSW & Victorian pulse crops, please take a photo and send it to us! We’re also interested in sampling populations of these pests, so if you encounter them, let us know where.
Reach out via:
Thanks to Andrew (Nutrien Ag Ariah Park), Terry Edis (Elders), Alex Tier (Nutrien Ag) and Rob Fox (Fox and Miles) for providing field reports.