Biology, images, analysis, design...
|"It has long been an axiom of mine that the little things are infinitely the most important" |
Chenopodium aphidIdentification & Distribution Biology & Ecology Damage & Control
Identification & Distribution:Hayhurstia atriplicis apterae are green covered with a white wax powder (see picture below).
Their siphunculi are very small and slightly swollen with a small flange, and are distinctly shorter than the finger-shaped cauda. The siphunculi and cauda are best seen in the dorsal and ventral micrographs of an aptera in alcohol below. The body length of Hayhurstia atriplicis is 1.5-2.9 mm.
Hayhurstia atriplicis live inside yellowish pseudogalls (see picture below) which are formed by rolling the leaves upwards.
This aphid feeds on many different species of plants in the goosefoot family, especially Atriplex and Chenopodium. In temperate climates Hayhurstia atriplicis has a sexual stage in the life cycle overwintering as eggs, but there is no host alternation. It is found widely in Europe and Asia, north and central Africa, and in North and central America.
Biology & Ecology:
Moran & Whitham (1990) looked at the host-mediated interaction between Hayhurstia atriplicis, which feeds above ground where it forms leaf galls, and Pemphigus betae which feeds underground on roots. Although the two aphid species never encounter one another directly, they share a common resource, the phloem sap of their host. The authors obtained four major results:
First, the root-feeding aphid Pemphigus betae had no significant effects on its hosts. In contrast, leaf galling by Hayhurstia atriplicis (see picture below) significantly reduced both plant mass and seed set.
Second, competitive interactions between the herbivore species depended on the level of host resistance to leaf galling by Hayhurstia atriplicis. On susceptible plants, leaf-galling colonies of Hayhurstia atriplicis greatly reduced Pemphigus betae numbers but, on plants resistant to galling, Hayhurstia atriplicis colonies were smaller and did not affect Pemphigus betae infesting roots of the same hosts.
Third, the interaction was asymmetrical; although Hayhurstia atriplicis had a strong negative effect on Pemphigus betae, the latter showed no measurable effects on Hayhurstia atriplicis.
Fourth, resistance to leaf-galling aphids was not correlated with resistance to root-feeding aphids.
We have found parasitoid mummies of Hayhurstia atriplicis several times, but each time the parasitoids had already emerged (see empty mummies below).
In Europe Hayhurstia atriplicis, is commonly parasitized by two parasitoids, Diaeretiella rapae and Ephedrus nacheri. Stary & Gonzalez (1991) pointed out that since the aphid parasitoid association is perennial, and Chenopodium groves commonly occur both in farmland and urban environments, they represent reservoirs of useful parasitoids. Diaeretiella rapae in particular is known to have a number of aphid pests in its host range.
Damage & Control:
There is some evidence that Hayhurstia atriplicis may play a role in the transmission of Potato virus Y (PVY) (Wyman et al., 2012 ) and Ethiopian Pepper Mottle Virus (EPMV) (Atsebeha et al., 2009 ). However, it does act as reservoir for aphid parasitoids (see above), so its benefits may outweigh its harm.