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(Coleoptera, Diptera, Hymenoptera and Lepidoptera)
by
Brian Pitkin, Willem Ellis, Colin Plant and Rob Edmunds
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BIDENS.
Bur-Marigolds. [Asteraceae]
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Fourteen
species of Bidens are recorded in Britain. These include
the native Nodding Bur-marigold (B. cernua) and Trifid Bur-marigold
(B. tripartita) and the introduced Black-jack (B. pilosa).
Four British miners are recorded on Bidens.
The
agromyzid Napomyza
lateralis feeds in the stems of Anthemis,
Bidens, Calendula, Dimorphotheca,
Matricaria, and Senecio
in Britain, although it has also been found in the inflorescence
of Matricaria (Spencer, 1972).
A key to the European miners recorded on Bidens is provided in Bladmineerders van Europa.
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Nodding Bur-marigold
Bidens cernua
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Key for the identification of the known mines of British
insects (Diptera and non-Diptera) recorded on Bidens
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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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Liriomyza strigata larva, lateral
Image: © Willem Ellis (Bladmineerders van Europa)
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Polyphagous. On more than 40 host genera in 15 families in Britain, including Bidens, 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: Mine not primarily above mid-rib. |
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2a > 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 'atricornis' has been recorded on Bidens in Britain.
Chromatomyia
horticola is recorded on 160 plant genera in 31 families of which 55 plant
genera in 19 families, but not yet on Bidens, in Britain. On Bidens elsewhere.
Chromatomya syngenesiae is recorded in Britain on 27 plant genera in the family Asteraceae and many more genera elsewhere, but not yet on Bidens, in Britain. On Bidens elsewhere.
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Chromatomyia
horticola (Goureau, 1851) [Diptera: Agromyzidae]
OR
Chromatomyia
syngenesiae Hardy, 1849 [Diptera: Agromyzidae]. |
2b > 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 Bidens, 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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