Otiorhynchus

Rafał Gosik, Peter Sprick, Jiří Skuhrovec, Magdalena Deruś & Martin Hommes, 2016, Morphology and identification of the mature larvae of several species of the genus Otiorhynchus (Coleoptera, Curculionidae, Entiminae) from Central Europe with an update of the life history traits, Zootaxa 4108 (1), pp. 1-67 : 32-33

Otiorhynchus (s. str.) meridionalis Gyllenhal, 1834

Material examined: 2 larvae ( Fig. 212 ). JKI, Braunschweig, climate chamber, breeding with Forsythia x intermedia Zabel and Ligustrum vulgare flowerpots, 0 8.02.2012, 1 ex., dto., 0 1.06.2012, 1 ex.; details see below.

Remarks about breeding and development. A few larvae and pupae of Otiorhynchus meridionalis were obtained from 1 breeding attempt in the climate chamber of the JKI in Braunschweig. On 24.06.2011 10 males and 10 females were released on 2 big flowerpots with Forsythia x intermedia. In October 1 plant had become dry and was replaced by Ligustrum ovalifolium . In December many larvae died due to too strong watering. The remaining larvae were taken to the CURCI in Hannover for regular pupae control (description see Gosik & Sprick 2012a). So for the description of the mature larva we had only 2 specimens at our disposal: one from 0 8.02.2012 and a second that refused to pupate from 0 1.06.2012. The adults used for breeding had been collected by Klaus Schrameyer in a front garden in the city of Heilbronn, and besides a record in Freiburg ( Maus 1998)—this is the only current locality of O. meridionalis in Germany ( Schrameyer & Bernau 2011).

The life-cycle of Otiorhynchus meridionalis is briefly outlined here; for more information see Bues et al. (1984). O. meridionalis is widespread for example in natural habitats of South France. Its life-cycle was studied by Bues et al. (1984) due to observations of damage in strawberry plantations ( Audemard et al. 1981). In the field, egg deposition tends toward maximum activity from end of July until September. Larvae develop until spring of the following year and pupate from March to beginning of May. This corresponds well with our breeding data. O. meridionalis did not show any diapause in the climate chamber, and larvae pupated due to the higher temperatures already in January and February. Around 3 weeks after pupation numbers of adults increase on the soil surface. In South France adults aestivate in July due to drought and high summer temperatures, apparently triggered by day length. It also of interest that a small proportion of adults overwinters and participates in egg-laying from May to mid-June. It is possible but unproven that the small proportion of recently emerged adults in the second half of the year is to trace back to the early egg-laying of overwintering adults. We observed overwintering of a more or less small proportion of adult specimens also in O. crataegi in the field, but noticed egg deposition in the lab not until mid-June (main egg-laying period is as in O. meridionalis in the second half of the year, in O. crataegi starting at the end of July).

Description ( Figs. 78–88 ).

Coloration. Head dark yellow; all thoracic and abdominal segments yellowish.

Body elongated ( Fig. 78 ). Chaetotaxy: Setae different in length, filiform, fine, transparent. Thorax. Prothorax with 4 long and 5 medium long to short prns; and 2 ps, different in length. Mesothorax with 1 medium long prs; 4 pds (ordered: 2 medium long and 2 long); 1 long as; 1 long eps; and 1 long ps. Chaetotaxy of meso- and metathorax similar. Each pedal area of thoracic segments well isolated, with 4 pda, different in length. Each thoracic segment with 1 short eus ( Fig. 79 ). Abdomen. Abdominal segments I–VIII with 1 short prs; 5 pds (ordered: 2 short, 1 long, 1 short and 1 long); 1 long and 1 minute sps [abd. seg. VIII only with 1 microseta]; 2 eps, different in length; 1 long and 1 short ps; 1 long lsts; and 2 eus ( Figs. 80, 82, 83 ). Abdominal segment IX with 3 ds, different in length; 1 long and 1 minute ps; and 2 sts, equal in length ( Figs. 81–83 ). Lateral lobes of abdominal segment X with 3 minute ts each.

Head subglobose (slightly narrowed) ( Fig. 84 ). Head capsule with 4 long des, des 1 and des 2 placed on central part of epicranium, des 3 located on frontal suture, des 5 located anterolaterally; 2 long fs, fs 4 placed anteromedially, fs 5 located near to antenna; 2 long les; and 1 very short ves. Postepicranial area with a group of 4 pairs of sensilla, frons with 3 pairs of sensilla. Stemmata (2 pairs) feebly visible. Antennal segment membranous, bearing 1 conical sensorium and 3–4 filiform sensilla. Clypeus 2.2 times as wide as long with 2 short cls, equal in length, placed posterolaterally ( Fig. 85 ). Labrum about 1.8 times as wide as long with 3 long, straight lms of different length, placed medially or mediolaterally; lms 1 somewhat shorter than other setae, all lms exceeding the outline of the labrum; the anterior margin of labrum rounded ( Fig. 85 ). Epipharynx with 3 finger-like als, different in length, 2 very short ams, different in length; and 2 very short mes; labral rods (lr) short, reniform, strong convergent ( Fig. 86 ). Mandible ( Fig. 87 ) bifid, teeth almost of equal height; with 2 mds, different in length; internal edge with a little triangular tooth. Maxilla ( Fig. 88 ) with 1 very long stps and 2 very long pfs, placed ventrolaterally; 1 very short mbs, situated ventrally. Mala with 7 dms, different in length and 4 straight vms, different in length. Maxillary palpi with two palpomeres; basal one somewhat larger than distal; basal palpomere with 1 mxps; distal palpomere with a group of 6 conical, cuticular processes apically; each palpomere with a sensillum. Praelabium heart-shaped ( Fig. 88 ), with 2 very short ligs and 1 long prms. Labial palpi with two palpomeres, relatively elongated; both palpomeres almost equal in length; praemental sclerite wide, well visible. Postlabium with 3 pms, different in length: pms 2 very long, 3 times as long as pms 1 and pms 3 ( Fig. 88 ).

Differential diagnosis. See “Key to larvae of selected Otiorhynchus species” and Tables 1, 2.

Figures

FIGURES 211 – 219. Mature larva, lateral view. 211 — O. aurifer, 212 — O. meridionalis, 213 — O. clavipes (= O. tenebricosus), 214 — O. fuscipes (= O. tenebricosus), 215 — O. lugdunensis, 216 — O. salicicola, 217 — O. ovatus, 218 — O. crataegi, 219 — O. rugosostriatus. (Photos by R. Gosik).

FIGURES 78 – 83. Otiorhynchus meridionalis; mature larva. 78 — habitus, lateral view, 79 — lateral view of thoracic segments, 80 — lateral view of abdominal segment I, 81 — lateral view of abdominal segments VIII – IX, 82 — ventral view of abdominal segments VIII – X, 83 — dorsal view of abdominal segments VIII – X. Abbreviations: Ab. — abdominal segment, Th. — thoracic s., I – X—number of segments, prns — pronotal seta (e), prs — prodorsal s., pds — postdorsal s., pda — pedal s., as — alar s., lsts — laterosternal s., eus — eusternal s., ps — pleural s., sps — spiracular s., sts — sternal s., ds — dorsal s., ts — terminal s.

FIGURES 84 – 88. Otiorhynchus meridionalis; mature larva and mouthparts. 84 — dorsal view of head, 85 — labrum and clypeus, 86 — epipharynx, 87 — left mandible, 88 — maxillo-labial complex. Abbreviations: des — dorsoepicranial seta (e), fs — frontal s., les — lateroepicranial s., ves — ventroepicranial s., at—antenna, st—stemmata, cls — clypeal s., lms — labral s., ams — anteromedial s., als — anterolateral s., mes — medial s., lr—labral rods, mds — mandible dorsal s., dms — dorsal malae s., vms — ventral malae s., mxps — maxillary palps s., pfs — palpiferal s., stps — stipal s., mbs — mandible basiventral s., prms — prelabial s., pms — postlabial s., ligs — ligular s.