Curculio elephas (Gyllenhal)
Taxonomic placing: Insecta, Holometabola, Coleoptera, Curculionidae.
Common name: Chestnut beetle, European chestnut beetle.
Geographical distribution: Europe, North Africa and the Middle East.
Host plants: Chestnut (Castanea sativa Miller) and holm oak (Quercus ilex L.).
Morphology: Body of adult brown-grey, elytra with many longitudinal parallel stripes, mouthparts (snout) very long. Larva apodous, pale-yellow, with brown thorax and head.
Life history: This univoltine beetle lives in the canopy of chestnut or oak trees. In late summer the females drill a hole in chestnuts or oak acorns and place one or two (seldom) eggs inside, fecundity being about 30-40 eggs/female. The emerging larva feeds on the fruit and at maturity drops to the ground, burrows into the soil and pupates. It can remain in diapause for one or more years; the adults live for about 4 weeks.
Economic importance: The chestnut weevil is an important pest of C. sativa; in some regions crop losses can reach 90%.
Horticultural methods: Collecting and destroying fallen chestnuts that may contain the larvae.
Sampling; Fruit (acorn) infestation rates can be determined from the first adult detection in the canopy until the harvest. Fifteen or more acorns are collected and the average infestation rate may be calculated from the number of chestnuts with pests inside or exit holes.
Chemical control: A treatment with a neonicotinoid applied against the adults controlled the pest in Italy; a pyrethroid was less effective.
Biological control: Applications of the entomopathgenic fungus Beauveria bassiana (Bals.) Vuill killed almost 100% of the pest population. Turkish indigenous entomopathogenic nematodes, evaluated in laboratory trials, resulted in almost total pest mortality. Several pest-associated bacteria were isolated and assayed in Turkey and provided about 30% weevil control.
Desouhant, E., Debouzie, D., Ploye, H. and Menu, F. 2000. Clutch size manipulations in the chestnut weevil, Curculio elephas: fitness of oviposition strategies. Oecologia 122: 493–499.
Karagoz, M., Gulcu, B., Hazir, S. and Kaya, H.K. 2009. Laboratory evaluation of Turkish entomopathogenic nematodes for suppression of the chestnut pests, Curculio elephas (Coleoptera: Curculionidae) and Cydia splendana (Lepidoptera: Tortricidae). Biocontrol Science and Technology 19: 755-768.
Kepenekci, I., Gokce, A. and Gaugler, R. 2004. Virulence of three species of entomopathogenic nematodes to the chestnut weevil, Curculio elephas (Coleoptera: Curculionidae). Nematropica 34: 199-204.
Paparatti, B. and Speranza, S. 1999. Biological control of chestnut weevil (Curculio elephas Gyll.; Coleoptera, Curculionidae) with the entomopathogenic fungus Beauveria bassiana (Balsamo) Vuill.(Deuteromycotina, Hyphomycetes). Acta Horticulturae 494: 459-466.
Paparatti, B. and Speranza, S. 2005. Management of chestnut weevil (Curculio spp.), insect key-pest in central Italy. Acta Horticulturae 693: 551-556.
Speranza, S. and Paparatti, B. 2010. Chemical control of chestnut weevils in central Italy. Acta Horticulturae 866: 411-415.
Yaman, M., Demirbag, Z., and Belduz, A.O. 1999. Investigations on the bacterial flora as a potential biocontrol agent of chestnut weevil, Curculio elephas (Coleoptera: Curculionidae) in Turkey. Biologia 54: 679-683.