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Hormaphidinae : Cerataphidini : Pseudoregma panicola
 

 

Pseudoregma panicola

Grass soldier aphid

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

Identification & Distribution

Pseudoregma panicola are only known from what are presumed to be their secondary hosts, where they reproduce entirely parthenogenetically. They live in dense wax-covered colonies on many species of grasses in the southern hemisphere (see first picture below). Adult apterae (see second picture below) are oval-shaped brownish black or brownish red-violet, with dark antennae and pale legs. The front of the head has a pair of short forward-pointing conical 'horns' with rounded tips sited between the antennal bases. The antennae have 4 or 5 segments. The apical rostral segment is 0.58-0.63 times as long as the second hind tarsal segment. The head and prothorax are fused. The sclerotised areas of cuticle are warty, particularly at the posterior margin of the prothorax (cf. Ceratovacuna spp., where those areas are smooth or wrinkled, not warty). Spinal and marginal wax glands are often present on all or most tergites. The siphuncular pores are slightly raised on dusky or dark-pigmented cones, with a few surrounding hairs (cf. Ceratovacuna, where these pores lack raised cones or surrounding hairs). The body length of adult Pseudoregma panicola apterae is 1.1-1.9 mm.

Images above by permission, copyright Nicholas A. Martin, Plant & Food Research.

Pseudoregma panicola alatae (see third picture above) are black with or without some dusting of wax. The pterostigma of the fore wings is greyish black. The frons has two short 'horns' with rounded tips. The antennae are 5-segmented. Antennal segment III bears 16-24 secondary rhinaria, segment IV has 6-9 and segment V has 4-11.

Like other Pseudoregma, these are eusocial aphids. Larvae of the apterae exist as two types - one of which develops into adults, and the other into a defensive 'soldier' form. These soldier forms are 'pseudoscorpion-like' nymphs with elongated legs and prominent pointed horn-like projections on the frons, and their fore legs are more sclerotic and sturdy. These soldiers attack by butting and gripping with their forelegs. Specialized 'horned soldiers' on the secondary host are unique to Pseudoregma, and perhaps half of the Ceratovacuna species. Noordam (1991) and Aoki & Kurosu (2010) found these 'horned soldier' morphs of Pseudoregma panicola halt development at the first instar. The pictures below were labelled as first and second instar soldiers (the latter is 1.17 times the body length of the first), but we could be looking at a normal first-instar and a soldier first-instar. Hormaphidinae soldiers developed on primary hosts are second instar but differ from those on the secondary host - they attack with their stylets rather than their horns. Unlike the unspecialized defensive forms found in these and other aphid taxa, neither of these soldier nymphs mature or reproduce.

Images above by permission, copyright Nicholas A. Martin, Plant & Food Research.

Pseudoregma panicola is found on many genera and species of tropical grasses including beard grass (Andropogon spp.), lovegrass (Eragrostis spp.), large-leaf bamboos (Indocalamus spp.), basket grass (Oplismenus spp.), panicgrass (Panicum spp.) and foxtail grass (Setaria spp.). They feed on the undersides of the leaves, stems and inflorescences. Sexual forms are not known, and populations are assumed to be anholocyclic. Pseudoregma panicola has a wide distribution in the southern hemisphere from Africa, southern India, east and south-east Asia to New Zealand and Australia. Their primary host, assuming it exists, is presumably an Asian Styrax species, upon which they make galls.

 

Other aphids on the same host

Acknowledgements

We are especially grateful to Manaaki Menua (Land Care Research) and Darren Ward, Head Curator New Zealand Arthropod Collection, for giving us permission to reproduce some of their images and for sending us the originals.

We have used the keys and species accounts of Noordam (1991) and Aoki & Kurosu (2010) together with those of 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).

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References

  • Aoki, S. & Kurosu, U. (2010). A review of the biology of Cerataphidini (Hemiptera, Aphididae, Hormaphidinae), focusing mainly on their life cycles, gall formation, and soldiers. Psyche 2010, Article ID 380381, 34 pp. Full text

  • Noordam, D. (1991). Hormaphidinae from Java (Homoptera: Aphididae). Zool. Verh. Leiden 270, 1-525. Full text