Biology and morphology of immature stages of Lixus canescens (Coleoptera: Curculionidae: Lixinae)

Abstract

Mature larvae and pupae of Lixus (Eulixus) canescens Steven, 1829 (Curculionidae: Lixinae: Lixini) are described and compared with known larvae and pupae of other Lixus species. The biology of the species was studied in Ukraine. A species of Crambe (Brassicaceae) was identified as host plant of both larvae and adults of this weevil. The weevil is very likely oligophagous. Lixus canescens prefers dry, sunny places, such as open areas of sand close to sea shores with growing host plants. Overwintering beetles emerge in the late spring (mid-May), and then feed and mate on the host plants. The highest level of activity of the adults was observed at the end of May. Larvae are endophagous in the host plant stem. At the end of July, the larvae pupate within the stem inside a pupation cell. Adults leave the cells at the end of summer and do not hibernate on the host plants. They then, most likely, spend some time feeding on the host plants and looking for suitable shelter in which to overwinter.

The morphology of the immature stages of two rare Lixus species (Coleoptera, Curculionidae, Lixinae) and notes on their biology

“…To date, larvae of 21 Lixus and two Hypolixus species have been described (Scherf 1964; Lee and Morimoto 1988; May 1994; Nikulina 2001, 2007; Zotov 2009a, b; Nikulina and Gültekin 2011; Gosik and Wanat 2014; Skuhrovec and Volovnik 2015), but a detailed description of the pupae is known for only 8 Lixus species (Scherf 1964; May 1994; Zotov 2009a, b; Gosik and Wanat 2014; Skuhrovec and Volovnik 2015). …”

“…May (1993) considered the increased number of pds on the meso- and metathorax and abdominal segments I–VII and the increased number of setae on the epipharyngeal lining ( als ) (i.e., higher than the most frequent number of setae in weevils) as diagnostic of the mature larva of the Lixinae subfamily, and the descriptions of mature larvae from the tribe Lixini ( Larinus species: Zotov 2009a, 2010; Gosik and Skuhrovec 2011; Lixus species: Scherf 1964; Lee and Morimoto 1988; May 1994; Nikulina 2001, 2007; Zotov 2009a, b; Nikulina and Gültekin 2011; Gosik and Wanat 2014; Skuhrovec and Volovnik 2015; Rhinocyllus conicus : May 1994) fit this diagnosis, as do all known species from the tribe Cleonini (Stejskal et al 2014, Trnka et al 2015). Currently, the comparison of both tribes, including key and detailed generic studies, is impossible due to our limited knowledge of the immature stages.…”

“…Approximately 170 Lixus species in 12 subgenera are found in the Palaearctic region; only Eutulomatus Desbrochers des Loges, 1893 and Parileomus Voss, 1939 do not occur in Europe (Gültekin and Fremuth 2013). The biology of these species is partially known but has primarily only been studied recently (e.g., Nikulina 1989; Volovnik 1994, 2007; Gültekin 2007; Gosik and Wanat 2014; Skuhrovec and Volovnik 2015). The immature stages of Lixus species usually develop in the stems (Meregalli 2014) or the roots of plants (Dieckmann 1983) but sporadically develop in the seed capsule (Gültekin 2005) or petiole (Gültekin 2007).…”

“…Some species from this genus are considered to be agricultural pests (e.g., Lixus incanescens Boheman, 1835 in Manole 1990; others in Volovnik 1988; Nikulina 1989), but others could be used for the biological control of selected weeds (e.g., Lixus filiformis (Fabricius, 1781) for musk thistle; Gültekin 2004) or have already been used for these purposes (e.g., Lixus cardui Olivier, 1807 in Australia; Nikulina and Gültekin 2011). Detailed morphological descriptions have been published for the larvae of 21 Lixus species, with detailed descriptions of the pupae being available for only eight species (see Scherf 1964; Lee and Morimoto 1988; May 1994; Nikulina 2001, 2007; Zotov 2009a, b; Nikulina and Gültekin 2011; Gosik and Wanat 2014; Skuhrovec and Volovnik 2015). …”

The morphology of the immature stages of Metadonus vuillefroyanus (Capiomont, 1868) (Coleoptera, Curculionidae, Hyperini) and notes on its biology

“…The detailed description of larvae and pupae and their comparisons with known descriptions as reported here demonstrates that it is possible to identify this species in its immature stages, as has been accomplished for other groups (i.e., Entiminae: Gosik and Sprick (2012a, b, 2013); Gosik et al (in press); Curculioninae, Tychiini: Skuhrovec et al (2014, 2015b); Lixinae: Gosik and Skuhrovec 2011; Gosik and Wanat 2014; Stejskal et al 2014; Skuhrovec and Volovnik 2015; Trnka et al 2015). This process is particularly valuable for rare and endangered species because finding larvae is typically much simpler than finding adults.…”