Weevil News


No. 24

3 pp.

10th January 2005

ISSN 1615-3472

Gültekin, L. (2005): New ecological niche for weevils of the genus Lixus Fabricius and biology of Lixus obesus Petri (Coleoptera: Curculionidae, Lixinae) - Weevil News: http://www.curci.de/Inhalt.html, No. 24: 3 pp., CURCULIO-Institute: Mönchengladbach. (ISSN 1615-3472).

New ecological niche for weevils of the genus Lixus Fabricius and biology of Lixus obesus Petri
(Coleoptera: Curculionidae, Lixinae)
Levent G

Lixus obesus Petri completes his generation in seed capsules of Prangos uloptera DC., a new ecological niche for the genus Lixus Fabricius, that is known to be stem-boring. Females open holes in young seed capsules and lay single eggs or in groups of 3-4 eggs. Larvae are feeding in seed capsules and pupate afterwards at the same place. The new generation of adults migrates after emerging by flight to hibernation sites. Thus, L. obesus produces one generation per year in northeastern Anatolia.
Six parasitoid species, Bracon urinator (F.), Exeristes roborator F., Scambus brevicornis Gravenhorst, Pteromalus sp. aff. vibulenus Wlk., Pimpline sp., and Mesopolobus sp., were reared from larval and pupal stages of L. obesus.

Key Words
Lixus obesus Petri, biology, host plant, new ecological niche for Lixus F., Curculionidae, Lixinae.

Lixus Fabricius cinsi için yeni ekolojik niş, ilk kez bu araştırmada belirlenmiş ve Lixus obesus Petri neslini, Prangos uloptera DC. bitkisinin tohum kapsülü içerisinde tamamlamıştır. Dişiler, genç tohum kapsülü üzerinde çukurcuk açarak yumurtalarını tek tek veya 3-4 tanesi yan yana olacak şekilde dizmektedir. Larvalar kapsül içerisinde tohumla beslenmekte ve aynı yerde pupa olmaktadır. Yeni nesil erginler, buradan çıkıp kışlamak için uçarak göç etmektedirler. Böylece, L. obesus Kuzeydoğu Anadolu Bölgesi’nde bir nesil vermektedir.
L. obesus’un larva ve pupa dönemlerinden altı adet parazitoid; Bracon urinator (F.), Exeristes roborator F., Scambus brevicornis Gravenhorst, Pteromalus sp. aff. vibulenus Wlk., Pimpline sp., ve Mesopolobus sp. elde edilmiştir.

The genus Lixus Fabricius 1802 has a nearly worldwide distribution and comprises over 500 species, in the Palaearctic region over 150 species (Csiki 1934; Ter-Minassian 1967) and is classified into 18 subgenera (Alonso-Zarazaga and Lyal 1999). Korotyaev and Gültekin (2003) argued that the host range includes several families of higher plants, but many, if not most, of the accepted subgenera are not known to be associated with a single plant family. The majority of the comparatively well-known species develops or at least feeds on species of several genera of a single plant family. With some plant families, e.g. the Chenopodiaceae, Brassicaceae, and Apiaceae, species of more than one subgenus of Lixus are associated, and it is not always clear if this reflects a multiple transition of the genus to plants of these families or the broad diversification of the phylogenetic lineages associated with the respective plants families. Only Palaearctic species of Lixus are known to develop on Brassicaceae; the majority belongs to the subgenus Compsolixus Reitter, 1916, in which 17 species have been placed by Csiki (1934), although the type species of this subgenus, L. junci Boheman, 1835, develops on Chenopodiaceae.
Csiki (1934) placed five species in the subgenus Callistolixus Reitter, 1916 and then Ter-Minassian (1967) combinated Lixus obesus Petri, 1904, Lixus furcatus Olivier, 1807 and Lixus tschemkenticus Faust, 1883 in this subgenus. L. obesus Petri is closely related to Lixus hypocrita Chevrolat, 1866 who should be transferred in this subgenus. In addition, it might be very interesting to investigate the biology of L. hypocrita Chevrolat which is distributed in Spain for comparing with L. obesus.
In spite of species-richness of the genus Lixus, for most of them biology, ecology, host plant and behavior are poorly known or unknown. In the present study, host plant, biology and parasitoids of Lixus obesus Petri, 1904 are investigated.

Material and Methods
This study was carried out in NE Anatolia in 2003. Biological observations were performed mainly in Aras Valley, 14 km E of Karakurt, Kars Province at an altitude of 1400 m. Observations were made in the field directly, some seed capsules were harvested, dissected and reared to adult stage in the laboratory; for rearing parasitoids, seed capsules were collected and cultured. To determine hibernation site preferences, ten adults of the new generation were released in the field at daytime, and their behaviour was observed.

Biological notes.
Adults [Fig. W24.1] of Lixus obesus Petri were seen on its host plant Prangos uloptera DC. (Apiaceae) on June 10th, 2002 and June 12th, 2003. Weevils fed on leaves, flowers and some also ate young seed capsules. On these dates mating and deposition of eggs was observed; both males and females mated several times. Copulation lasted more than 30 minutes. Usually, two or three pairs were observed per plant. Adult specimens have dust-like secretions on body as camouflage (but perhaps there is also another function), and it was not easy to detect this weevil on the host plant. Females deposited eggs usually solitarily or in groups of 3-4 in one seed capsule [Fig. W24.2], making approximately 1 mm deep holes. After deposition of eggs, females closed the holes with a yellowish liquid, that hardened in time and turned to brown color acting as an opercula. When adults fed on young seed capsules, this part turned to brown color and abnormal shape. Newly hatched larvae (15 June 2003) bored directly into and fed on seeds. More than one young larva can be found per seed capsule (probably 1st and 2nd stage) [Fig. W24.3], but only one larva can develop into adult stage in one seed capsule [Fig. W24.4]. Most of larvae passed into pupal stage in the third week of July (22 July 2003) at the same place [Fig. W24.5]. And there was always one teneral adult per seed capsule. From this time on, adults of new generation started to emerge; teneral individuals remained several days within the plants, then they opened holes for emergence. During this period, most of seed capsules dried and when adults opened holes, some of the seed capsules were damaged. Because no hibernation places could be found in natural habitats, neither under hiding objects nor in plant tissues in 2002, some adults from the new generation were released to nature and migration by flight was observed. Thus, L. obesus produces one generation per year in northeastern Anatolia.
These results show that the genus Lixus is able to extend its ecological niche by developing in seed capsules of an Apiaceae plant species; all other species with known biology are stem borers.

Parasitoids. Bracon urinator (F.) (Hymenoptera: Braconidae), Exeristes roborator F., Scambus brevicornis Gravenhorst, and Pimpline sp. (Hymenoptera: Ichneumonidae), Pteromalus sp. aff. vibulenus Wlk., and Mesopolobus sp. (Hymenoptera: Pteromalidae) were reared from L. obesus larvae and pupae. Immature stages of L. obesus have a rich parasitoid spectrum. A parasitoid larva feeding on a dead larva of L. obesus [Fig. W24.6] ] and a parasitoid emerging hole on a seed capsule were observed  [Fig. W24.7].

Habitat and host plants. Prangos uloptera DC. [Fig. W24.8] along Aras Valley and Çoruh Valley.
Following Ter-Minassian (1967), L. obesus develops in the shoots of Prangos ferulacea in Armenia. But this record is probably erroneous and attributed to a confusion with the larva of Lixus furcatus Olivier, 1807 whose larvae develop in the stems of several Prangos species in Turkey as my observations have shown.

Distribution. NE Turkey. Ağrı, Erzurum, Kars; Armenia.
Caucasus (Petri 1904/5: 33; Csiki 1934: 107; Ter-Minassian, 1967: 131), Lebanon, Turkey (Tatvan), Italy (Fremuth 1982: 249).

Examined material. NE Turkey. Ağrı Prov.: 42 km SE of Horasan, 2000 m, 31.VIII.2003 (L. Gültekin), 15 M, 26 F (reared) Erzurum Prov.: 10 km N of Tortum, 1350 m, 10 VI 2002 (L. Gültekin), 3 M, 3 F; 1 IX 2002 (L. Gültekin) 1 M (reared); Kars Prov.: 31 km E of Horasan, 1500 m, 18.VII.2002 (Ö. Çalmaşur), 1 M, 1 F; 14 km E of Karakurt, 1400 m, 1.VI.2002 (L. Gültekin), 1 M, 1 F; 28-29.VII.2003 (L. Gültekin) 4 M, 3 ♀ (reared); 12.VI.2003 (L.Gültekin), 2 M, 3 F; 32-33 km W of Tuzluca, 1100 m, 2.VI.2002 (L. Gültekin), 1 F.
Armenia. Amberd, 3.VI.1986 (P. Kazaryan), 1 F.

I am sincerely grateful to Dr. V. I. Dorofeyev (Botanical Institute, Russian Academy of Sciences, St. Petersburg) for identification of the plant species, Dr. B. A. Korotyaev for contribution and consultation at joint expedition during summer 2003 in Turkey, Dr. S. V. Belokobylskij for identification of braconid wasps; Dr. D. R. Kasparyan for ichneumonid wasps; Dr. K. Dzhanokmen for chalcid wasps (Zoological Institute, Russian Academy of Sciences, St. Petersburg). Also, I would like to express my cordial thanks to Dr. Peter Sprick (Hannover, Germany) for linguistic revision and Dr. Peter Stüben (Mönchengladbach, Germany) for re-arrangement of color pictures. The study was supported by the Collaborative Linkage Grant No. 978845 of the NATO Life Science and Technology Programme.  

Csiki, E., (1934):
Curculionidae: subfam. Cleoninae. – 152 p. in Coleopterorum catalogus. W. Junk, S. Schenkling, Berlin, 134.
Fremuth, J., (1982): Cleoninae aus der Türkei und den angrenzenden Gebieten (Coleoptera, Curculionidae). Fragm. Entomol. 16 (2). P. 239–258.
Petri K., (1904/1905): Bestimmungs-Tabellen der europäischen Coleopteren, 55. Curculionoidea, Lixus F. Paskau: 1–62.
Ter-Minassian, M. E., (1967): Weevils of the Subfamily Cleoninae in the Fauna of the USSR. Tribe Lixini. Keys to the USSR fauna published by the Zoological Institute, Academy of Sciences of the USSR, 95. Nauka Publishers, Leningrad Branch, Leningrad, 1967. 166 pp.
Korotyaev, B.A. and L. Gültekin, (2003): Biology of two weevils, Lixus ochraceus Boheman and Melanobaris gloriae sp. n. (Insecta: Coleoptera, Curculionidae), associated with Tchihatchewia isatidea Boissier, a cruciferous plant endemic of Turkey.
Entomologische Abhandlungen, 61(1): 93-99.

Levent Gültekin
Atatürk University, Faculty of Agriculture, Plant Protection Department, 25240,
e-mail: lgul@atauni.edu.tr
Levent Gültekin is a member of the CURCULIO-Institute: "www.curci.de")