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CALENDULA. Marigolds [Asteraceae] |
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Two species of Calendula are recorded in Britain - Field Marigold (C. arvensis) and Perennial Pot Marigold (C. officinalis). Both species are introduced. The polyphagous agromyzid Liriomyza strigata is the only Diptera miner recorded on Calendula in Britain. Elsewhere the agromyzids Chromatomyia syngenesiae, Liriomyza huidobrensis, Liriomyza sativae, Liriomyza strigata, Liriomyza trifolii and Phytomyza marginella, are recorded mining Calendula. 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). No non-Diptera miners are recorded on Calendula in Britain. Elsewhere one British non-Diptera miner, Cnephasia incertana, is recorded on Calendula (see below). A key to the European miners, based on characteristics of the mines, immature stages and where relevant the larval cases, recorded on Calendula is provided in Bladmineerders van Europa. This includes Cnephasia incertana, Cnephasia asseclana, Cnephasia stephensiana, Chromatomyia syngenesiae, Liriomyza strigata and Phytomyza marginella but not Liriomyza huidobrensis, Liriomyza sativae or Liriomyza trifolii. |
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Note: Diptera larvae may live in a corridor mine, a corridor-blotch mine, or a blotch mine, but never in a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Pupation never in a cocoon. All mining Diptera larvae are leg-less maggots without a head capsule (see examples). They never have thoracic or abdominal legs. They do not have chewing mouthparts, although they do have a characteristic cephalo-pharyngeal skeleton (see examples), usually visible internally through the body wall. The larvae lie on their sides within the mine and use their pick-like mouthparts to feed on plant tissue. In some corridor miners frass may lie in two rows on alternate sides of the mine. In order to vacate the mine the fully grown larva cuts an exit slit, which is usually semi-circular (see Liriomyza huidobrensis video). The pupa is formed within the hardened last larval skin or puparium and as a result sheaths enclosing head appendages, wings and legs are not visible externally (see examples). 1 > 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 (Bladmineerders van Europa). A linear mine on the upper surface, usually following the midrib and showing side branches along the veins. The frass is in strings (British leafminers).
Liriomyza strigata (Meigen, 1830) [Diptera: Agromyzidae]. |
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Key
for the identification of the mines of British
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Note: The larvae of mining Coleoptera, Hymenoptera and Lepidoptera may live in a corridor mine, a corridor-blotch mine, a blotch mine, a case, a rolled or folded leaf, a tentiform mine or sandwiched between two more or less circular leaf sections in later instars. Larva may pupate in a silk cocoon. The larva may have at least six legs (although they may be reduced or absent), a head capsule and chewing mouthparts with opposable mandibles (see video of a gracillarid larva feeding). Larvae of Hymenoptera and Lepidoptera usually also have abdominal legs (see examples). Frass, if present, never in two rows. Unless feeding externally from within a case the larva usually vacates the mine by chewing an exit hole. Pupa with visible head appendages, wings and legs which lie in sheaths (see examples).
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1 > Leaf-miner: In the first instar the larva mines the leaves, forming short, irregular, blotch-like mines, but in later instars it lives externally, feeding in spun leaves and often twisting those of tender shoots. Larval head light-brown or yellowish brown, edged with black postero-laterally, ocellar area blackish; prothoracic plate black edged with whitish anteriorly; abdomen dull dark green; pinacula distinct, black, sometimes brownish but with black bases to setae; anal plate large, black (Bradley et al., 1973). Small, full depth mine without a definite shape; little frass. Some silk is deposited in the mine. The larva soon leaves the mine and continues feeding among spun leaves (Bladmineerders van Europa).
Cnephasia incertana (Treitschke, 1835) [Lepidoptera: Tortricidae] |
| Last updated 31-Jan-2012 Brian Pitkin |  |
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