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Aphidinae : Macrosiphini : Macrosiphoniella yomogicola
 

 

Macrosiphoniella yomogicola

Japanese mugwort aphid, Mugwort princess aphid

On this page: Identification & Distribution Biology & Ecology Colour & Ant attendance Other aphids on the same host

Identification & Distribution

Adult apterae of Macrosiphoniella yomogicola (see first picture below) are grey-green to blackish or orange to rust brown, usually with dark cross-bands on the dorsal abdomen. These cross-bands are sometimes much-reduced and broken into segmental groups of sclerites. (cf. Macrosiphoniella kuwayamai & Macrosiphoniella hikosanensis, both on Artemisia, neither of which have any dark cross-bands or groups of sclerites on the dorsal abdomen). The antennae, legs, siphunculi and cauda are all dark. The head has at least 12 dorsal hairs in addition to the frontal ones. Antennal segment III has 8-13 small or moderate secondary rhinaria near its base, or on the basal one third. The rostrum reaches the hind coxae. The apical rostral segment is much narrower and somewhat shorter than the penultimate, about 2-4 times as long as wide, tapering, pointed apically, and with some pairs of long fine hairs. Abdominal tergites II-IV each have at least 50 long, fine hairs arranged irregularly, not in transverse rows (see first picture below where long hairs on tergites are clearly visible). Postsiphuncular sclerites are small or absent. The black siphunculi are reticulate over the distal half, at most about as long as cauda, and without hairs (cf. Macrosiphoniella chaetosiphon, which has several long hairs on the siphunculi). The cauda has more than 20 hairs. The body length of adult Macrosiphoniella yomogicola apterae is 2.0-3.2 mm. Immature grey-green apterae are pale green, immature orange-brown apterae appear to be yellow (or these may mature to yellow adults).

Note: Neither Matsumura (1917) nor Takahashi (1939) mention the dark cross bands on the dorsum of the apterous vivipara. This is suprising given that it is the most obvious discriminating character of Macrosiphoniella yomogicola, and is subsequently used in the keys of Miyazaki (1971) and Blackman in Aphids on Worlds Plants.

First image above by permission, copyright Akihide Koguchi, all rights reserved.
Second image copyright Watanabe under a cc by-nc 4.0 licence.

The alate vivipara has 21-28 small circular secondary rhinaria on antennal segment III, mostly in a row on the basal two-thirds or more. Segment III also has many stiff hairs, which are blunt or very slightly capitate apically, almost as long as, or shorter than, the width of the segment. Segment IV lacks rhinaria. The siphunculi are black, rather slender, somewhat longer than the cauda, narrowed on the distal half, not expanded at the base, reticulate on the distal two-thirds, and sometimes slightly curved. The cauda is also black, gradually tapering, not constricted, bluntly pointed apically, stouter than the siphunculi and with many lateral setae. The legs are very long and slender.

Macrosiphoniella yomogicola is monoecious holocyclic on several Artemisia spp., especially mugwort (Artemisia vulgaris). It has also been recorded on Chrysanthemum indicum. Unusually for a member of the Macrosiphini, Macrosiphoniella yomogicola is usually attended by ants, sometimes under earthen shelters (Miyazaki 1971). It is found in Japan, China, and east Siberia.

 

Biology & Ecology

Colour and ant attendance

Macrosiphoniella yomogicola has a mutualistic relationship with the Asian ant Lasius japonicus. The aphids take up phloem sap from their host plant and excrete excess sugars as honeydew. The ants consume the large amounts of honeydew produced and in return will actively defend the aphids against some predators.

The mugwort aphid shows colour polymorphism, with red and green-black as the most common types. Being parthenogenetic, red aphids produce red daughters, green aphids green daughters. Watanabe et al. (2016) first showed that ant attendance is necessary for the survival of aphid colonies. They also showed that in Macrosiphoniella yomogicola the ants strongly favour aphid colonies with intermediate proportions of the two color morphs - where green morphs comprise approximately 65% of the colony. This system represents the first case of a balancing polymorphism that is not maintained by opposing factors, but by a symbiotic relationship.

Watanabe et al. (2018) then showed that the ant has a preference for the green morph of Macrosiphoniella yomogicola because that morph excretes a higher quality honeydew in terms of the sugar content. The red morph retains a larger proportion of the sugars that it obtains from the host plant, and so can reproduce at a higher rate. The green morph therefore runs a risk of being displaced by the red one. But if ants are attending the aphids the reproduction rate of the green morph increases up to that of the red aphids. Thus, in the presence of ants, the proportion between green and red morphs is stable.

Why the ants maintain the red morph in their attended aphid colonies is less clear. One possibility for maintaining the red morph is for the sexual reproduction of overwintering eggs (which produce both morphs the following year); there was some evidence that the red forms survived better than the green in late summer, allowing this species to produce adequate numbers of sexuparae in late autumn.

 

Other aphids on the same host

Macrosiphoniella yomogicola has been recorded from 7 Artemisia species (Artemisia indica, Artemisia japonica, Artemisia montana, Artemisia princeps, Artemisia schmidtiana, Artemisia stelleriana, Artemisia vulgaris).

Acknowledgements

We are especially grateful to Akihide Koguchi for allowing us to reproduce the image of Macrosiphoniella yomogicola from his blog page.

We have used the keys and species accounts from Matsumura (1917), Takahashi (1939) & Miyazaki (1971) along with information from Roger Blackman & Victor Eastop in Aphids on Worlds Plants. 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

  • Matsumura, S. (1917). A list of the Aphididae of Japan, with description of new species and genera. Journal of the College of Agriculture, Tohoku Imperial University 7 351-414. Full text

  • Miyazaki, M. (1971). A revision of the tribe Macrosiphini of Japan (Homoptera: Aphididae, Aphidinae). Insecta Matsumurana 34(1), 1-247. Full text

  • Takahashi, R. (1939). Some Aphididae from Hokkaido. Insecta Matsumurana 13(4), 114-128. Full text

  • Watanabe, S. et al. (2016). Color polymorphism in an aphid is maintained by attending ants. Science Advances 2, e1600606. Full text

  • Watanabe, S. et al. (2018). Ants improve the reproduction of inferior morphs to maintain a polymorphism in symbiont aphids. Sci Rep. 8, #2313. Full text