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(Coleoptera, Diptera, Hymenoptera and Lepidoptera)
by
Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds
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TROPAEOLUM.
Nasturtiums. [Tropaeolaceae]
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Two species of Tropaeolum are recorded in Britain. These include Nasturtium (T. majus), Flame Nasturtium (T.
speciosum).
Six British miners are recorded on Tropaeolum.
A key to the European miners recorded on Tropaeolum is provided in Bladmineerders van Europa. |
 Nasturtium
Tropaeolum majus
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Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Tropaeolum
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1a > Leaf-miner: A distinctive mine primarily above mid-rib, with irregular short
lateral offshoots into leaf blade. Pupation external (Spencer, 1972:
51 (fig. 172), 55; Spencer, 1976:
270, 271 (fig. 486)).
Branched,
whitish, upper-surface corridor; main axis overlying the midrib;
side branches overlying the main lateral veins. (In Campanula and Phyteuma the mine is much less branched, sometimes nothing
more than a corridor on top of the midrib). Frass in rather long
strings. Usually the mines begins as a long and narrow, shallow,
tortuous lower-surface corridor that ends upon the midrib but otherwise
is not associated with the leaf venation. Often this initial corridor
is filled with callus, and then even less conspicuous. Pupation
outside the mine.
A
linear mine on the upper surface, usually following the midrib and
showing side branches along the veins. The frass is in strings. |
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Polyphagous. On more than 40 host genera in 15 families, but not yet on Tropaeolum, in Britain,. Widespread
throughout Britain. Also recorded in the Republic of Ireland.
Widespread in continental Europe.
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Liriomyza strigata (Meigen, 1830) [Diptera: Agromyzidae]. |
1b > Leaf-miner: Corridor-blotch
mine, normally dorsal; usually whitish; in small leaves it lies
characteristically in the centre of the leaf often touching the
petiole; in larger leaves it lies to one side of the mid-rib. Frass
deposited in green clumps near the leaf margin. Pupation usually
external, sometimes in a separate pupation mine.
Oviposition
whitin the leaf, at the lower surface. The first part of the mine
is a long, sometimes very long, corridor, that mostly will be overrun
by the later developments. Generally this corridor is directed,
frequently guided by a thick vein, to the midrib. The next section
of the mine is large, irregular blotch overlying the basal section
of the midrib. Locally large chunks of midrib tissue are consumed.
From this central blotch excursions are made into the leaf blade:
generally upper-surface, less often lower-surface and locally full-depth.
In plants with narrow leaves, like Diplotaxis, the mine may
occupy the entire width of the leaf. Often several larvae together
in a mine. Frass blackish green, powdery, in clouds, sometimes along
the sides of the corridors, later more in the periphery of the mine
and in the end of extensions of the blotch, sometimes seemingly
absent. (Often the frass can only be seen after the mine has been
opened). Pupation generally in the ground, rarely within he leaf,
in a short mine without frass. Hendel (1928a) described the biology,
larva and puparium.
An initial narrow gallery then leads to a blotch on the midrib of the leaf.
Watch a video of a scaptomyzid fly larva on Arabidopsis on YouTube by mash92587. |
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Polyphagous. On
numerous genera of Brassicaceae, Asteraceae, Papaveraceae, Resedaceae,
Tropaeolaceae and Violaceae, including Alliaria, Barbarea, Brassica, Cheiranthus, Cochlearia, Coincyia, Conringia, Diplotaxis, ? Eruca, Erysimum, ? Hesperis. Lepidium, Matthiola, Raphanus, ? Rorippa and Sinapis in Britain. On additional genera of these families and Fabaceae elsewhere. Widespread, from Caithness in the north to Cornwall in the south of Britain. Also recorded in the Republic of Ireland, Europe, the East Palaearctic, Near East and Neartic Region.
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Scaptomyza flava (Fallén, 1823) [Diptera: Drosophilidae]. |
1c > Leaf-miner: Mine linear, whitish, both upper and lower surface. Pupation internal,
at the end of the mine with the anterior spiracles projecting through
the epidermis (Spencer, 1976:
433).
Upper-surface,
less often lower-surface corridor. Frass in isolated grains. Pupation
within the mine, usually in a lower-surface puparial chamber.
A long whitish upper surface corridor, which eventually goes lower surface. |
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Two
highly polyphagous species of Chromatomyia, with indistinguishable
mines, have been recorded in Britain. These are syngenesiae (Hardy) and horticola (Goureau) which can only be distinguished by the male genitalia. Both species are widespread in Britain and elsewhere, although syngenesiae is almost entirely restricted to Asteraceae. Records on Asteraceae not based on examination of male genitalia are treated in this account as Chromatomyia 'atricornis'.
Chromatomyia horticola is recorded on 160 plant genera in 31 families, of which 55 plant
genera in 19 families, including Tropaeolum, in Britain.
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Chromatomyia
horticola (Goureau, 1851) [Diptera: Agromyzidae]. |
1d > Leaf-miner: Irregular
mine, locally shallow, elsewhere much deeper, giving it a mottled
appearance. In broadleaved plants the mine often begins as a blotch
with stellate extensions, but sometimes as a very fine, shallow
corridor. In grasses the mine often begins in the leaf sheath. The
frass is very fine-grained, initially scattered, later in aggregates.
The egg is deposited on the plant surface, and the empty egg shell
remains visible. But the larvae are able to leave their mine and
restart elsewhere, thus mines without an egg shell can be found
as well. The larva also leaves the mine before pupation. Pupation
takes place in a newly made, small, blotch mine without frass; this
mine may be made in another plant (species). |

Mine
of Hydrellia griseola on Glyceria fluitans
Image: © Willem Ellis (Bladmineerders van Europa)
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Polyphagpus. On
? Alisma, ? Damasonium,
? Sagittaria, ? Bellis,
? Rorippa, Tropaeolum, ? Lychnis,
? Stellaria,
? Carex,
? Cyperus,
? Scirpus,
? Hydrocharis,
? Stratiotes,
? Lamium,
? Lemna,
? Allium, Arrhenatherum,
? Polygonum,
? Potamogeton,
? Veronica,
? Typha in Britain.
On ? Alisma,
? Damasonium, ? Sagittaria,
? Bellis, ? Rorippa, Tropaeolum, Lychnis,
? Stellaria, Carex,
? Scirpus, Trifolium,
? Hydrocharis, Lamium,
? Lemna, Allium, Papaver, Agrostis, Alopecurus, Apera, Arrhenatherum, Avena, Avenula, Brachypodium, Briza, Bromus, Calamagrostis, Dactylis, Desmazeria, Digitaria, Echinochloa, Eleusine, Elymus, Festuca, Gaudinia, Glyceria, Holcus, Hordeum, Lagurus, Lolium, Panicum, Phalaris, Phleum, Phragmites, Poa, Secale, Setaria, Triticum,
? Polygonum, ? Potamogeton, Veronica, ? Typha and Verbena elsewhere.
Widespread in England. Also recorded in the Republic of Ireland.
Widespread in the Palaearctic region. Also recorded from Nearctic
and Australasian Regions.
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Hydrellia
griseola (Fallén, 1813) [Diptera: Ephydridae]. |
1e > Leaf-miner: Rather small, untidy, full depth, often branched corridor, often close to the leaf margin. Sides irregularly eaten out. Frass in a greyish-green central line that is interrupted from time to time, sometimes partly in strings. In times of rain the frass may run out and appear greenish.
Usually several mines in a leaf. The body is whitish; head greyish brown with Y-shaped lighter marking. Pronotum with a pair of brownish shields. The mandibles have two teeth. |

Mine
of Ceutorhynchus minutus on Raphanus sativus
Image: © Willem Ellis (Bladmineerders van Europa) |

Ceutorhynchus minutus larva, lateral
Image: © Willem Ellis (Bladmineerders van Europa) |
Polyphagous. On numerous genera and species of Brassicaceae, Capparaceae, Resedaceae and Tropaeolaceae, including Cochlearia, but not yet on Tropaeolum, in Britain and Tropaeolum elsewhere. Widespread in Britain and continental
Europe. Also recorded in the Republic of Ireland.
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Ceutorhynchus
minutus (Marsham, 1802) [Coleoptera: Curculionidae]. |
1f > Leaf-miner: A short, irregular, linear upper surface mine on any part of the
leaf. Also recorded from young pods (Bland, 1997a).
Long
corridor mine. As a rule the first part of the mine is lower-surface,
the later part upper-surface. Often the loops are so dense that
a secondary blotch is the result. Because upper- and lower-surface
corridor segments often cross, the mine obtains a strange array
of transparant patches. There is no association with the midrib.
Frass in strings and thread fragments. Pupation outside the mine;
exit slit in upper epidermis.
Mine not associated with the veins or midrib of the leaf (It is this character which enables distinction from another Agromyzid pest species - Liriomyza huidobriensis). The larvae may leave one leaf (if not large enough) and enter another leaf, via the petiole). It exits the leaf to pupate through a semi-circular slit in the upper surface of the leaf. |
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Polyphagous. On 119 plant genera in 31 plant families of which only 4 plant genera in 2 plant families, but not yet on Tropaeolum, in Britain. Local, probably introduced
to Britain. Widespread in continental Europe particularly in Botanical
Gardens and glasshouses. Also recorded in Egypt.
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Liriomyza bryoniae (Kaltenbach, 1858) [Diptera: Agromyzidae].
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