Araecerus fasciculatus (De Geer, 1775)

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POLYPHAGA Emery, 1886

CURCULIONOIDEA Latreille, 1802

ANTHRIBIDAE Billberg, 1820

CHORAGINAE Kirby, 1819

ARAECERINI Lacordaire, 1865

ARAECERUS Schönherr, 1823 

Thought to be originally native to India this species is now established and widespread in tropical and subtropical regions worldwide, and because it develops in various traded food products it is regularly imported and temporarily established in heated premises in temperate regions; in the UK it was a regular and sometimes serious pest among imported food products in urban areas but is now rare and infrequent due to control measures. The common names refer to perhaps the most affected crops but a wide range of hosts have been recorded e.g. corn, dried potato, yam, garlic and many kinds of seeds, nuts, fruits and dried herbs, and in warmer temperate regions it has survived outside and infected apple branches, causing fruit to drop, citrus fruits and has overwintered as a larva in the stems of Ambrosia trifida L. in the United States. It has even been bred on strychnine beans. Both adults and larvae feed on fungi associated with decaying organic matter; adults cause no serious damage but larvae burrow among the host, extensively destroying the tissue and introducing fungal pathogens as they go, and as the fecundity is high and development times short, very large and destructive populations soon build up. In tropical areas there may be 6 overlapping generations a year with all developmental stages present among the host material, fecundity depends on population density and food availability and has been measured between 33 and 176 eggs per female. Eggs are laid directly into host material and larvae burrow and feed indiscriminately; among stored fruits and nuts they bore into the flesh, often leaving a just a hollow skin in which they will pupate and through which the adults will bore to escape and continue breeding among further host material. Freshly emerged adults will feed before mating, causing irregular and random patterns of discolouration and after mating may disperse by flight to infect other products but a high relative humidity is needed before they will oviposit and a moisture content of less than 12% will effectively protect products from infection. Because of the high commercial value some crops are protected by fumigation with carbon dioxide or aluminium phosphate over a week or so in sealed chambers. In temperate regions it has not been known to survive winters outside heated facilities.

2.0-4.5mm. Entirely pale to dark brown with dense recumbent pubescence, odd-numbered elytral interstices with alternate pale and dark brown patches of recumbent pubescence giving the insect a mottled appearance. Head, including the short and transverse rostrum, quadrate with large convex eyes and prominent curved and bifid mandibles. Antennae long and slender; the third segment slightly longer than the second, with a narrow, elongate and 3-segmented club, the insertions in front of the eyes and visible from above. Pronotum broadest at acute posterior angles and narrowed to a rounded anterior margin, basal margin widely bisinuate, surface evenly convex and densely punctured. Scutellum small and clothed with conspicuous white pubescence. Elytra broadly elongate and gently curved to continuously rounded apices leaving the pygidium exposed, striae consist of rows of weakly impressed punctures that are not always visible among the pubescence, interstices finely punctured and much wider than the striae. Legs long and slender, the tarsi about as long as the tibiae; the male front legs much longer compared to the female, femora not toothed ventrally and tibiae without terminal spurs, all tarsi long, with the second segment curved apically around the base of the bilobed third, fourth segment tiny and often not visible, terminal segment long and curved. Claws long and gently curved, smooth and acutely pointed and with a distinct blunt tooth at the base.

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