Larinus capsulatus, Gültekin, Levent, 2008

Gültekin, Levent, 2008, Taxonomic review of the stem-inhabiting trehala-constructing Larinus Dejean, 1821 (Coleoptera: Curculionidae): New species, systematics and ecology, Zootaxa 1714, pp. 1-18 : 12-16

Larinus capsulatus sp. n. ( Figs. 15–20 )

This weevil produced only one generation a year in the Aras Valley, Turkey. The season’s first adults of L. capsulatus appeared on the host plant in the fourth week of May (May 26, 2000; May 23, 2001) (Table, 1.). They fed on the leaves and stems of E. orientalis . Several days later, multiple mating events, each lasting 30– 60 minutes, were observed. Feeding, mating, and oviposition lasted until the end of July (July 29, 2000). Each plant had more than two individuals, their number reaching occasionally six (N=6). The females of L. capsulatus laid eggs in the stem and leaf petioles ( Figs. 15, 16 ), making a 2–3 mm deep cavity with their rostrum.

Locations Date Adult Mating Egg Larva Pupa New adult Number of observation

21 km E of Horasan 11.VI.1998 x 1 15.VII.1998 x 1 2.VI.1999 x 1 26.V.2000 x 1 16.VI.2000 x x 1 18.VII.2000 x x x x 1 28.VII.2000 x

29.VII.2000 x x x x 1 7.VIII.2000 x 1 23.V.2001 x 1 17.VI.2001 x 1 2.VIII.2001 x 1 4.VIII.2001 x 1 10.VIII.2001 x 1 21.VIII.2001 x 1 1.VI.2002 x 1 21.IX.2002 x 1 22.VII.2003 x 1 25.IX.2003 x 1 22.VI.2007 x 1

11 km W of Karakurt 14.VII.1999 x 1

21 km SE of Horasan 3.VIII.2002 x 1 27.IX.2003 x 1 6.X.2003 x 1

16 km E of Horasan 1.VIII.2007 x 1

Subsequently the surface of the eggs and the surrounding plant tissue were covered with a secretion ( Figs. 15, 16 ). This oviposition secretion turns black after some time. The number of deposited eggs per plant may vary from 1 to 26 depending on the plant size and on the number of adults. The egg stage lasted 11–12 days in the laboratory (N=2). Eggs were found in the field up to the third week of July (July 18, 2000). The larvae started hatching from the middle to the last week of June (June 26, 2000; June 17, 2001), and for some period feed inside of petiole or stem. After completing growth, they began constructing the capsule on the plant stem using a secretion and small plant fragments ( Fig. 17 ). These capsules ( Fig. 18 ) appear to protect the insect from adverse climatic conditions such as direct sun light, rain, desiccation, and from natural enemies. One to nineteen larvae may be present in a stem (N=19). The first mature larvae of the season were observed from the third week of July to the first week of August (July 18, 2000; August 4, 2001). The pupae were found in the capsules from the last week of July up to late September ( Fig. 19 ) (July 28, 2000; August 10, 2001; September 27, 2003). The pupal stage lasted 7–11 days when observed in the laboratory at room temperature. Adults of the new generation were recorded in the capsules from the third week of July up to beginning of October (July 22, 2003; August 7, 2000; August 21, 2001; October 6, 2003). Adults of the new generation remained in the capsules several days and then emerged after opening the capsule ( Fig. 20 ).

Host plants. Echinops orientalis ( Fig. 21 ) is only host plant determined in the territory of Aras Valley ( Fig. 22 ).

Parasitoid. The ichneumonid wasp Exeristes roborator F. ( Hymenoptera : Ichneumonidae ) was reared from a L. capsulatus pupa in 2002.

Larinus rudicollis Petri ( Figs. 23, 24 )

This species produced one generation per year. Adults were observed on May 6, 2003 in the Bingöl Province on E. sphaerocephalus . Usually one or two adults were found on a single plant, whereas L. capsulatus usually congregated in groups of 1–6 individuals. The adults are very active and quickly move from one plant to another either by crawling or flying, whereas adults of L. capsulatus move more slowly. Adults of L. rudicollis feed on leaves and young flowerheads, leaving circular feeding holes in the process. Females deposited indivual or more than one eggs into leaf petioles. The surface of each egg was covered by a secretion which turned black and hardened. Young larva produce a longitudinal gallery along the midrib until advancing to the main stem or lateral branches. After reaching the stem, they proceed by through the plant tissue and eventually started constructing a capsule around their body. The color of the capsule was pale brownish-gray and its texture was rough ( Fig. 23 ). The place is used for larval feeding and as a pupal chamber. Teneral adults emerged from some time after eclosion ( Fig. 24 ).

Host plants. Echinops sphaerocephalus , E. pungens and Echinops sp. were determined as host plants in eastern regions of Turkey.

Figures

FIGURES 15 – 20. Life stages of L. capsulatus sp. n. (Aras Valley, 2003). 15 – oviposition mark; 16 – eggs in petiole; 17 – larva in capsule (trehala); 18 – capsules on stem; 19 – pupa in capsule (trehala); 20 – newly emerged adult.

FIGURES 21 – 26. Echinops orientalis, host plant of L. capsulatus sp. n. 22 – habitat of L. capsulatus sp. n. at Aras Valley. 23 – capsule (trehala) of L. rudicollis. 24 – new generation adult of L. rudicollis emerging from capsule. 25 – capsule of L. hedenborgi dorsal view; 26 – ventral view of capsule.