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Idiopterus nephrelepidis

Black fern aphid

On this page: Identification & Distribution Biology & Ecology: Habitat Life cycle Other aphids on the same host

Identification & Distribution

Adult apterae of Idiopterus nephrelepidis are pear-shaped and black, with transverse rows of white flat-topped setae on the dorsal tubercles of the abdomen and thorax. The legs and antennae are pale and translucent, with the antennae ringed with black. The antennal terminal process is 4.5-5.0 times the length of the base of antennal segment VI. The apical rostral segment is about twice as long as the second hind tarsal segment. The siphunculi of apterous Idiopterus nephrelepidis have the basal quarter to a third dark, but distal parts are pale. The siphunculi are about twice the length of the cauda which is black and tongue-shaped with 5 hairs. The body length of the adult aptera is 1.2-1.6 mm.

Both images copyright Dave Appleton, all rights reserved.

The alate viviparous female of Idiopterus nephrelepidis (see second picture above) has dorsal hairs not placed on tubercles, but on small scleroites. Marginal sclerites are present. Antennal segment III has 7-14 secondary rhinaria, segment IV has 1-5, and V has 0-3. The forewing has a large clear spot in the pterostigma and all veins are surrounded by broad black borders. The hind wings are reduced in size.

The clarified slide mounts below are of adult viviparous female Idiopterus nephrelepidis : wingless, and winged.

Micrographs of clarified mounts by permission of Roger Blackman, copyright AWP all rights reserved.

Idiopterus nephrelepidis feeds on various species of ferns including spleenworts (Asplenium), bracken ferns (Pteridium) and polypodies (Polypodium). Reproduction is entirely parthenogenetic, and no sexual forms have been found. The species is thought to have originated in the neotropics but has since spread over much of the world. In northern temperate regions it is generally thought to be restricted to glasshouses, caves and other sheltered environments - although the chapel ruins from which it is reported here seem rather less sheltered than most previous known habitats.

 

Biology & Ecology

Habitat

In northern temperate climates the black fern aphid is most commonly recorded from ferns in glasshouses. For example Tasheva-Terzieva et al. (2011) reported Idiopterus nephrelepidis from Bulgaria living on ornamental ferns (Nephrolepis exaltata, Asplenium nidus and Pteris cretica) in four greenhouses in Sofia and Varna. Dense colonies of apterous viviparous females and immatures were observed causing leaf deformation of the ferns.

The aphid has also been found on ferns growing in caves. Steffan (2009) found it in the spring cave of Schum in Macedonia, Yugoslavia on the ferns Ceterach officinarum Asplenium trichomanes and Dryopteris sp.

Dave Appleton has now found this aphid outdoors in England. It was feeding on harts-tongue fern (Asplenium scolopendrium, the first picture below shows young fronds) growing on a rather exposed north-facing wall of a ruined chapel at North Elmham in Norfolk, UK in November 2018. Returning to the same site this year in early May 2019 he found the colony had successfully overwintered, and was producing apterae.

Second image copyright Dave Appleton, all rights reserved.

On his most recent visit he found a bigger colony with alates in a more sheltered site in the ruins (see second picture below). They were on hart's-tongue half way down the wall at the top of the steps. In that position they were sheltered by the walls on both sides and trees above, and overhung slightly by the rocks of the ruins.

Life cycle

As far as is known, reproduction of the black fern aphid is entirely parthenogenetic since no sexual forms have ever been found. This makes it all surprising to find the aphid overwintering outside glasshouses and caves - even if the ruins do provide a degree of protection (albeit not from a syrphid larva in the image below).

Image copyright Dave Appleton, all rights reserved.

The images above and below show both adult & immature aphids. They live year round on ferns, reproducing parthenogenetically.

Image copyright Dave Appleton, all rights reserved.

 

Other aphids on the same host

Acknowledgements

We are extremely grateful to Dave Appleton for the images of live Idiopterus nephrelepidis, and for making extra visits to the field site to take additional photos. We are also grateful to Dr Jit Thacker for putting us in touch with Dave regarding his find of Idiopterus, and to Dr Roger Blackman for generously allowing us to use his images of clarified mounts.

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

  • Steffan, A.W. (2009). A free field find and new host plants of Idiopterus nephrelepidis D. in Yugoslavia (Hemiptera: Aphididae) (in German). Journal of Applied Entomology 50 (1-4), 403-407. Abstract

  • Tasheva-Terzieva, E. et al (2011). First report of Idiopterus nephrelepidis Davis, 1909 (Hemiptera: Aphididae) from Bulgaria. ZooNotes 26: 1-4. Full text