Lymantor coryli (Perris, 1853)

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POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

CURCULIONIDAE Latreille, 1802

SCOLYTINAE Latreille, 1804

DRYOCOETINI Lindemann, 1876

Lymantor Løvendal, 1889

This tiny and inconspicuous scolytid occurs throughout lowland Europe from Spain to Greece, Turkey and Ukraine and north to the UK and into southern provinces of Fennoscandia, it extends east into Asia Minor and western Russia and is recorded from North Africa and the Canary Islands but, apart from sometimes occurring in numbers in commercial orchards, it is very sporadic and generally rare throughout. The species is sometimes referred to as occurring in North America but these are almost certainly based on misidentifications. In the UK it is known from only a few sites in southeast and central England and possibly a single site in the northwest, but again records are sporadic and the species is regarded here as very rare. Adults have been recorded through most of the year in Europe but in the UK it occurs from June until September, they disperse by flight early in the season and otherwise spend most of their time under bark. A wide range of host trees have been recorded including, among others, Field Maple (Acer campestre L.), Norway Maple (A. platanoides L.), Field Elm (Ulmus minor Mill.), oaks (Quercus L.), Beech (Fagus sylvatica L.), Alder Buckthorn (Frangula alnus Mill.), Bird Cherry (Prunus padus L.), Rowan (Sorbus aucuparia L.) and Lime (Tilia cordata Mill.), but in the UK  the usual hosts are Hazel (Corylus avellana L.) and Hornbeam (Carpinus betulus L.). In central and Black Sea regions of Turkey the species has long been recorded from damaged kiwi (Actinidia chinensis Planch.) stems and shoots but larvae (if this identification is correct) have recently been found developing within fruits where these are grown commercially near to woodland or hazelnut orchards, here the larvae damage fruits directly and cause then to drop prematurely. Breeding occurs early in the season and females bore into decaying  bark on small branches or twigs, often where it is infested with fungi of the genus Diaporthe Nitschke (1870) (Ascomycota: Diaporthaceae), more especially perhaps D. syngenisia (Fr.) Nitschke where these have formed apothecia, and produce short but wide (compared with the size of the beetle) brood galleries. Larvae bore out at right angles to the brood gallery before turning and following the phloem tubes, the complete galleries are about 6 cm long and pupation occurs at the end of each one. Larvae feed on decaying wood and by gnawing into perithecia, they develop rapidly and are fully-grown within a few weeks. It is likely that the species naturally occurs in small numbers e.g. in Turkey, which supplies about 80% of the world’s hazelnuts (430,000 to 800 000 tons annually) and maintains almost 690,000 ha of plantations, it has always been very local and rare compared to other scolytid pests. Adults and larvae sometimes occur in numbers in the same wood sample in spring and early summer, adults sometimes occur in flight-interception traps and they have been attracted to alcohol baited traps in Turkey, but sampling is likely to be rather random as several other tiny scolytids also attack Hazel.

Lymantor coryli

Lymantor coryli

© U.Schmidt

1.8-2.2 mm. Elongate and almost cylindrical, entirely shiny brown, dorsal surface with sparse semi-erect pale pubescence. Head strongly deflexed and hidden from above, vertex convex, frons and clypeus flattened between reniform eyes. Antennal scape longer than the funiculus and expanded from the middle, funiculus four-segmented; the first segment broadly expanded, the second quadrate and expanded from the base, and the third and forth short and transverse, club flattened and almost round and with two widely-curved rows of fine setae (among the general pubescence) representing the sutures. Pronotum slightly elongate, parallel-sided from a rounded apical margin to obtuse posterior angles, in lateral view smoothly convex and curved down to the apical margin, surface asperate across the apical third, otherwise densely and quite strongly punctured but for a smooth median longitudinal line, basal margin not bordered. Scutellum small but obvious. Elytra parallel-sided or slightly dilated from rounded shoulders to a continuous apical margin, surface moderately strongly but not densely punctured, these are largely random but usually form partial striae, declivity depressed, without teeth or tubercles, and almost impunctate between the sutural and the third striae, the second striae usually deepened in the apical half or third before the smooth declivity. All tibiae broadened from the base, truncate across the apex and with an external series of teeth in the apical half. Tarsi five segmented and narrow, the third segment not bilobed and the apical segment long and curved. Distinguished by the small size, evenly convex pronotum, four-segmented funiculus and the form of the antennae club.