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Protrama radicis

Daisy-root aphid

Identification & Distribution  Biology & Ecology 

Identification & Distribution:

Adult apterae of Protrama radicis are dirty-white to pale-yellow or pale brownish-green. Siphunculi are present as pores placed on small, pigmented, cones. The head and appendages are dark. The antennal terminal process of Protrama radicis is 0.33-0.69 times the length of the base of the sixth antennal segment. The body length of the adult aptera is 2.5-3.4 mm.

 

The hind tarsus is 0.72-0.87 times the length of the hind tibia (cf. Protrama flavescens where the hind tarsus is only 0.59-0.70 times as long as the hind tibia). Below, an apterous Protrama radicis is shown dorsally and ventrally, in alcohol.

 

Protrama radicis lives in ant attended colonies on the roots of various Asteraceae, especially Arctium, Carduus, Centaurea, Cirsium and Cynara.

 

Biology & Ecology:

This species is probably rather common, but is seldom seen because it lives underground feeding on the roots of plants. Finding them is facilitated by the frequent presence of ants around the stem collar of an affected plant. Unfortunately the ants tend to depart rapidly once their aphis colony is disturbed, and we have yet to obtain photos of them tending this species.

The picture above shows an apterous female Protrama giving birth to a nymph. When feeding the nymphs tend to aggregate in a cluster (see picture below).

One unusual feature of the morphology of both Protrama and Trama  aphids is the greatly extended hind tarsal segment. This is conspicuous in live specimens because of their tendency to adopt an unusual 'stiff-leg' posture, with one or both hind legs held outstretched behind them (see picture below).

Bilodeau et al. (2013)  has described how some aphids freeze as a defense strategy against insect parasitoids, so this could be the strategy adopted by Protrama against its predators and parasitoids. Defensive behaviour with a stiff-legged posture to feign death has also been described in Brazilian treetoads (Bertoluci et al., 2007 ).

Acknowledgements

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors 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

  •  Bertoluci et al. (2007). Defensive behaviour with stiff-legged posture in the Brazilian tree toads Dendrophryniscus brevipollicatus and D. leucomystax (Anura, Bufonidae). Alytes 25 (1-2) Full text 

  •  Bilodeau, E. et al. (2013). Survival to parasitoids in an insect hosting defensive symbionts: A multivariate approach to polymorphic traits affecting host use by its natural enemy. PLoS ONE 8(4), e60708. Full text