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Aphidinae : Macrosiphini : Acyrthosiphon kondoi
 

 

Acyrthosiphon kondoi

Blue alfalfa aphid

On this page: Identification & Distribution Other aphids on the same host Damage & Control

Identification & Distribution

Adult apterae of Acyrthosiphon kondoi are bluish green. Their antennae are light brown basally, progressively darkening to the terminal process (cf. Acyrthosiphon pisum, invasive in America, which has dark bands at the apices of each antennal segment - but see note below). The antennal terminal process is 4.7-6.0 times as long as the base of antennal segment VI (cf. Acyrthosiphon loti in Eurasia & South America, which has the terminal process 2.7-4.2 times the length of the base, and cf. Acyrthosiphon pisivorum (= ? Acyrthosiphon phaseoli) in China, whose terminal process is about 3 times as long as the base). The antennal terminal process is less than 0.2 mm long (cf. Acyrthosiphon pisum, which has a terminal process 0.25-0.40 mm long).

Note: The difference in the antennal markings between Acyrthosiphon kondoi and Acyrthosiphon pisum is not always very clear cut.

Images above copyright Jesse Rorabaugh under a public domain (CCO) licence.

The siphunculi are without a subapical zone of polygonal reticulation (cf. the cosmopolitan Macrosiphum euphorbiae & Macrosiphum creeli in North America, both of which a subapical zone of polygonal reticulation). The siphunculi are 1.6-2.1 times the caudal length (cf. Acyrthosiphon astragali in South Asia, which has siphunculi 2.0-2.6 times the length of the cauda, and cf. Acyrthosiphon gossypii in southern Europe and South Asia, which has siphunculi 2.5-3.5 times as long as the cauda). The siphunculi are only slightly attenuated distally (cf. Acyrthosiphon pisum, which has its siphunculi attenuated distally such that they are thinner than the hind tibiae at their respective midlengths). The first picture below show a clarified mount of an apterous Acyrthosiphon kondoi.

First image above copyright Pest and Diseases Image Library, Bugwood.org under a Creative Commons License.
Second image above copyright Jesse Rorabaugh under a public domain (CCO) licence.

Alatae of Acyrthosiphon kondoi (see second picture above) have a darker brown thorax than Acyrthosiphon pisum, and have 7-9 secondary rhinaria confined to the basal half of antennal segment III.

Acyrthosiphon kondoi feeds on the stems and leaves of alfalfa (Medicago sativa), and other Medicago species, sweet clovers (Melilotus spp.), clovers (Trifolium spp.) and canary clovers (Dorycnium & Lotus spp.) as well as on milkvetches (Astragalus spp) and some members of the pea & bean family (Fabaceae). In its native Japan Acyrthosiphon kondoi is monoecious holocyclic, but seems to be anholocyclic in most other places. It is an important pest of alfalfa, most notably where it is invasive such as North and South America, South Africa, Australia and New Zealand.

 

Other aphids on the same host

Acyrthosiphon kondoi has been recorded on 5 Medicago species (Medicago falcata, Medicago lupulina, Medicago polymorpha, Medicago sativa, Medicago truncatula).

Acyrthosiphon kondoi has been recorded on 2Melilotus species (Melilotus albus, Melilotus officinalis).

Acyrthosiphon kondoi has been recorded on 3 Trifolium species (Trifolium ambiguum, Trifolium pratense, Trifolium repens).

 

Damage and control

Acyrthosiphon kondoi is a major pest of alfalfa in USA, Australia and New Zealand where it was introduced in the 1970s. It is considered far more damaging than Acyrthosiphon pisum. Moderate levels of infestation on mature lucerne can stunt stems, cause leaf yellowing and sometimes premature leaf fall, and reduce root reserves. The damage is most severe when aphids attack the new regrowth following winter cutting. Mature plants are more tolerant of attack. Honeydew production can lead to the growth of sooty moulds which further reduce yield. Acyrthosiphon kondoi is also a vector of a number of plant viruses including Alfalfa mosaic virus, Lucerne Australian latent virus and Lucerne transient streak virus.

Planting resistant varieties has been the most effective means of controlling aphids in alfalfa. Natural enemies can be encouraged by border harvesting or strip cutting. Hippodamia convergens and Coccinella septempunctata are both known to consume blue alfalfa aphids, as well as the parasitoids Aphidius smithi and Aphidius ervi. Economic treatment thresholds for application of insecticides if natural enemies fail to keep the aphids in check are 10-12 per stem for young plants and 40-50 per stem for more mature plants. More information on pest management of the blue alfalfa aphid can be found in UC Pest Management Guidelines (2020).

Acknowledgements

We thank the photographers named in the picture credits above for the various images shown. We have used the species description of Takahashi (1965) together with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. We fully acknowledge these authors and those listed in the reference sections as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure provided by Blackman & Eastop (2006).

Useful weblinks

References

  • Takahashi, R. Some new and little known Aphididae from Japan (Homoptera). Insecta Matsumurana 28(1), 19-61. Full text

  • UC Pest Management Guidelines (2020). Alfalfa: Blue Alfalfa Aphid. Agriculture and Natural Resources, University of California. Full text