Lissorhoptrus oryzophilus Kuschel, 1952

Perone, Paolo, Cerrato, Cristiana & Meregalli, Massimo, 2022, Saproxylic weevils and edaphic beetles as indicators of environmental quality of relict forests in Piedmont lowlands (Coleoptera), Fragmenta entomologica 54 (2), pp. 283-296 : 291

Lissorhoptrus oryzophilus Kuschel, 1952

In Bosco della Partecipanza, we recorded the rice water weevil Lissorhoptrus oryzophilus , native to North America and detected for the first time in Italy in 2004 ( Caldara et al. 2004). This species is considered one of worst pests of rice ( Oryza sativa ) in the world and is now widespread in northern Italy, mainly in the rice-growing areas between Piedmont and Lombardy ( Chersi et al. 2010; Lupi et al. 2010). L. oryzophilus was found in both sampling sites of Partecipanza, in an extremely large number of specimens: 729 individuals were counted (and some more escaped from the funnels), most of which were found in the close-to-natural forest site, the alder-ash wood. Since the species is linked to the wet environments of rice fields ( Lupi et al. 2015), the high number of L. oryzophilus in this site is probably due to the high and rather constant humidity of the substrate, that makes it suitable as an area for shelter and hibernation ( Caldara et al. 2004; Chersi et al. 2010). Indeed, in the September sampling period, when the rice weevil is active, very few specimens were found. L. oryzophilus is a polyphagous pest, which feeds on rice and other herbaceous plants present in the agroecosystem ( Lupi et al. 2009); therefore food competition with native edaphic weevil species, associated to decaying wood, can be excluded. However, the scarcity of native weevils found at Partecipanza, in a patch of apparently good habitat conditions, could be caused by spatial competition with specimens of L. oryzophilus .