Otiorhynchus rugosostriatus (Goeze, 1777)
Originally native to the Western Palaearctic region this invasive weevil has become established in many parts of the world through the trade in horticultural products, it was first recorded in the United States in 1876 and is now a widespread pest of nursery stock; it has spread to Australia and New Zealand and is established in South and Central America. The natural range includes much of Europe, Northwest Africa and parts of Asia Minor, extending north into the south of Fennoscandia and the UK. Here it is locally common across England and Wales north to South Yorkshire, including The Isle of Wight, Anglesey and Man, but only occasionally recorded further north. Natural habitats are well-vegetated open areas on dry soils in sunny situations on wooded margins, ruderal sites, heaths and moors, sand dunes etc. and on the continent they often occur in vineyards; the adults are nocturnal and during the summer may often be found by sweeping mixed hedgerows at night, during the day they generally hide among moss and leaf-litter but may occasionally become active on the host plants. Natural hosts include a range of herbaceous plants where the larvae are external root-feeders but the species is also synanthropic, occurring in domestic gardens and commercial fruit nurseries where they may become serious pests. Adults are parthenogenetic and so far only females have been recorded, they become active early in the year and feed at night on margins of leaves, producing circular indentations which do little damage to the plants but do alert growers to the presence of the species, fruits most vulnerable include currants, gooseberry and raspberry and a range of ornamental fruits but they are more generally an important pest of strawberries. Oviposition occurs from late June although under artificial conditions this may vary, each female deposits groups of eggs into the soil around the base of the host plants or, occasionally, they may be laid on petioles close to the ground, and each will lay several hundred eggs. Larvae emerge after about 3 weeks and begin to feed on young roots, they continue feeding into the autumn when they will overwinter and, if fully grown they will pupate in the soil or continue feeding and developing in the spring and it is at this time when they may severely damage young plants starting to grow; affected plants produce poor growth and may wilt or even die, and those that survive produce only poor quality fruit. Larvae pupate in a cell beneath the soil surface and adults eclose after a few weeks; they remain in the cell for a week or two before emerging although those eclosing during the winter will usually remain in place until the early spring. Adults will survive until the autumn when the majority will die but some are able to survive and will overwinter among litter or in the soil, and these may become active during mild winter spells. Adults may be collected during the summer by sweeping or searching suitable host material by night, allotments and gardens are often productive and when a specimen is found the plants should be repeatedly searched as others are bound to appear. Alternatively the creamy-white larvae, which measure about 8mm when fully grown, or the pale pupae may be excavated from among roots where an infestation is known to occur.
Otiorhynchus rugosostriatus 1
Adults are very distinctive; 5.5-7.6mm and dark brown in colour, usually with the forebody darker than the elytra. Head flat and roughly textured, with large weakly-convex eyes and a broad rostrum which exposes the scrobes from above, is longitudinally impressed from the frons to the antennal insertions, and is expanded apically. Antennae thin and very long, scape gradually and only weakly expanded apically, the third segment much longer than the second and the club narrow and elongate. Pronotum quadrate and evenly rounded laterally, surface covered with dense and quite strongly raised tubercles. Elytra much broader than the pronotum, with sloping shoulders and a continuously-rounded apical margin, interstices shiny and strongly sculptured, giving an overall appearance of a strong, transversely rugose surface, pubescence fine, semi-recumbent and evenly distributed i.e. not forming discrete patches. Legs dark reddish-brown, generally coloured as the elytra; all femora smooth, without a ventral tooth, anterior tibiae curved and widened internally close to the apex.