Rhopalapion longirostre (Olivier, 1870)

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POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

BRENTIDAE Billberg, 1820

APIONINAE Schönherr, 1823

Rhopalapion Schilsky, 1906

This species is native to southern and south-western Europe and Asia Minor, where it has always been regarded as generally common, but it has undergone a rapid and extensive expansion from this range during the 20th century and is now widely established; it was first recorded from Germany in 1974, France in 1982, Poland in 2002, and has been known from central Asia since the 1960s. Further afield it was first recorded in North America in 1914 and is now widespread in the United States and southern Canada. First recorded as established in the UK during the early 21st century, it is now widespread and locally common across southeast England and there are scattered records across south and central England, it is thought to have been introduced and at least partly spread by the horticultural trade and this seems to be the case throughout its European expansion as well. Adult weevils are present year-round; they overwinter in the ground below host plants and are active over a long season from March or April until the autumn, peaking in abundance during June and July, they may occur on a range of mallows (Malvaceae) but are almost always associated with hollyhocks (Alcea rosea L.) in domestic gardens and other placed where they are cultivated, as well as wasteland and verges etc. Mating occurs from early spring after a period of feeding on tender young foliage, and females oviposit in developing flower buds, the very long rostrum being used to chew through the calyx and petals and into the ovary so that eggs can be placed among developing seeds on which the larvae will feed. Adults may cause damage to leaves and both sexes use the rostrum to reach into flower buds and consume seeds but their effect on the plants is generally insignificant. Part of the attraction of the plant as an ornamental in herbaceous borders etc, is that it is self-sowing and although it is actually biennial it appears to be perennial as overlapping generations provide an abundance of flowers, and here the larvae may cause significant damage as they destroy developing buds and when present in numbers prevent the plant from setting seed. Larvae develop and pupate within unopened buds, which tend to remain attached to the plant, and adults emerge  in the  summer or, where  eggs have  been laid  later in  the year, they

Rhopalapion longirostre

Rhopalapion longirostre

will not eclose until the following spring. The life cycle is generally rapid; larval development takes between 4-6 weeks during the summer and the pupal stage lasts about a week but, at least in temperate northern areas of Europe, the species is thought to be exclusively univoltine. Adults are easily sampled by tapping leaves and flowers over a sheet, they mate over a long season and seem to do so very frequently; mating pairs may be found among flower buds at any time, often while the female has her rostrum deeply embedded in an unopened bud and often through the night, they usually occur in numbers and populations tend to continue over several years.

2.4-3.5mm. Easily distinguished among our fauna by the combination of elongate-oval body, pale legs and very long rostrum. Body and rostrum shiny black, coxae and trochanters black, femora and tibiae orange or red, tarsi dark reddish-grey, dorsal surface with dense pale pubescence which extends onto the base of the rostrum, ventral surface with coarser and paler pubescence. Eyes large, weakly convex and separated by slightly less than the width of the rostral base, temples short and usually hidden within the thorax, male rostrum about as long as the head and pronotum combined, female rostrum almost twice this length. Antennae long and slender, especially the club which is about three times longer than wide in both sexes. Pronotum elongate, broadest about the middle and narrowed to distinct anterior and posterior angles, surface smoothly convex and without a median impression towards the base. Elytra broadest about the middle (female), or almost parallel-sided (male), in side view not forming an angle with the pronotum, with sloping shoulders and a continuously-curved apical margin, striae much narrower than the interstices and clearly visible through the pubescence, the sutural stria not reaching the base and usually beginning about the apex of the scutellum. Femora unarmed, middle and hind tibiae produced apically into small external tooth, front tibiae simple. Claws distinctly toothed at the base.