Otiorhynchus (Pocodalemes) crataegi Germar, 1824

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 : 45-48

Otiorhynchus (Pocodalemes) crataegi Germar, 1824

Material examined: 7 larvae ( Figs. 218 , 227 ). For the description larvae from breeding in the lab and from fieldsampling could be used: 10.6.2011, 3 ex., collected under Taxus baccata trees in a tree nursery in Bad Zwischenahn ( Germany, northwestern Niedersachsen near Oldenburg; Figs. 220, 222 ); 16.11.2011, 4 ex., reared with Cotoneaster dammeri C.K. Schneid. by Thorsten Ufer, Ellerhoop, for efficacy tests of entomopathogenic nematodes against these larvae.

Further larvae of this species were sampled between March and June in a tree nursery in Bad Zwischenahn, where it occurred as single species and in rather large numbers between the roots of Taxus baccata and Taxus media Rehd. trees, usually at low soil depth (mainly between 5 and 25 cm).

Remarks about breeding and development. The life-cycle of this species, unknown up until very recently, could be clarified in great parts during the soil-dwelling weevils project (see Sprick & Stüben 2012). Oviposition of the major part of the specimens was not observed until end of July in the lab, achieved a maximum in August and September and ended in October. This largely corresponds with data on the emergence and activity of this species in the field (activity data received from pitfall traps and the regular use of a beating tray). Teneral adults, light colored and weak adults hatch from the pupa usually in great numbers in July (and in lower numbers until September) and begin to lay eggs around three weeks later when sclerotization is completed. Due to climate conditions, emergence may start up to 4 weeks earlier or even 2 or 3 weeks later in the season (see Sprick & Stüben 2012). Very likely young larvae overwinter, begin to feed early in the season and achieve the last larval stage usually in May and June. In June, larvae pupate and 2 or 3 weeks later young weevils hatch from the soil. The emergence of young adults is continued to the end of the season (with a decrease of the total number and an increase of the ratio). Due to the low soil depth, larval development is strongly influenced by soil cover and spring temperatures, and the variation in the beginning of the adults’ activity and of the egg-laying period is caused by these factors. In every year of the investigation, a varying part of overwintering adults was recorded, but their significance for the survival of the population was apparently low, as egg-laying rates were usually low, only a few of them oviposited already in June.

In 2010 and 2011, young larvae were sampled on 29.03. of both years. In 2010, 20 mature larvae were collected on 02.06.; 8 of 9 larvae kept in a box had already pupated on 11.06.2010. In 2011, 3 pupae and 4 larvae were directly collected between the roots of Taxus baccata and T. media .

Description ( Figs. 133–143 ).

Coloration. Head light yellow; all thoracic and abdominal segments white or light yellow; cuticle smooth.

Body slender, elongated ( Fig. 133 ). Chaetotaxy: Setae different in length, relatively long, filiform, white to yellow. Thorax. Prothorax with 6 long and 1 short prns; and 2 ps, different in length. Mesothorax with 1 short prs; 4 pds (ordered: 1 long, 1 short and 2 long); 1 long as (sometimes with an additional short seta); 1 eps; and 1 ps. Chaetotaxy of meso- and metathorax similar. Each pedal area of thoracic segments well isolated, with 6 pda, different in length. Each thoracic segment with 1 short eus ( Fig. 134 ). Abdomen. Abdominal segments I–VIII with 1 short prs; 5 short pds (ordered: 1 long, 1 short, 1 long, 1 short and 1 short); 1 long and 1 minute sps [abd. seg. VIII only with 1 microseta]; 2 eps, different in length; 1 long and 1 minute ps; 1 long lsts; and 2 eus ( Figs. 135, 137, 138 ). Abdominal segment IX with 3 ds, different in length; 1 very long and 1 minute ps; and 2 sts, equal in length ( Figs. 136–138 ). Lateral lobes of abdominal segment X without ts.

Head subglobose, narrowed bilaterally ( Fig. 139 ). 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 2 very short ves; all setae (except ves) almost equal in length. Stemmata (2 pairs) well visible. Antennal segment membranous, bearing 1 conical sensorium and 4–5 filiform sensilla. Clypeus 3 times as wide as long with 1 very short cls, placed posterolaterally ( Fig. 140 ). Labrum about 2 times as wide as long with 3 long, straight lms of different length, placed medially or mediolaterally; lms 2 somewhat longer than other setae, all lms exceeding the outline of the labrum; the anterior margin of labrum almost rounded ( Fig. 140 ). Epipharynx with 3 finger-like als, different in length; 3 ams, different in length; and 2 very short mes (see comments about ams and mes in Material and Methods); labral rods (lr) elongated, strongly convergent ( Fig. 141 ). Mandible ( Fig. 142 ) bifid, teeth of almost equal height; with 2 mds, different in length; internal edge with a triangular tooth. Maxilla ( Fig. 143 ) 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 3 straight vms, almost equal in length. Maxillary palpi with two palpomeres of almost equal length; basal palpomere with 1 mxps; distal palpomere with a group of 7 conical, cuticular processes apically; each palpomere with a sensillum. Praelabium heart-shaped ( Fig. 143 ), with 3 very short ligs and 1 long prms. Labial palpi with two palpomeres, relatively elongated; both palpomeres almost equal in length; praemental sclerite well visible. Postlabium with 3 pms, different in length: pms 2 very long, 2 times as long as pms 1 and 3 times as long as pms 3 ( Fig. 143 ).

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 226 – 231. Breeding and collecting of the weevil larvae. 226 — O. aurifer larvae from breeding in the climate chamber, 227 — O. crataegi larva and pupa in the field—size compared with a Taxus needle, 228 — O. rugosostriatus larva in the Panicum virgatum field in Wiesbaden-Schierstein, 229 — O. rugosostriatus, young adult, just hatched, found under Panicum virgatum, as before, 230 — O. armatus, 2 mature larvae on graph paper, 231 — O. armadillo larva in a flowerpot used for breeding. (Photos by P. Sprick).

FIGURES 220 – 225. Breeding and collecting of the weevil larvae. 220, 222 — Sampling sites of O. crataegi under Taxus in Bad Zwischenahn, 221 — Breeding of O. armadillo in flowerpots with Euonymus fortunei cultivar Emerald ' n Gold, 223, 225 — Sampling sites of O. rugosostriatus under Panicum virgatum in Wiesbaden-Schierstein, 224 — Breeding of O. aurifer in a flowerpot with Viburnum tinus. (Photos by P. Sprick).

FIGURES 133 – 138. Otiorhynchus crataegi; mature larva. 133 — habitus, lateral view, 134 — lateral view of thoracic segments, 135 — lateral view of abdominal segment I, 136 — lateral view of abdominal segments VIII – IX, 137 — ventral view of abdominal segments VIII – X, 138 — 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.

FIGURES 139 – 143. Otiorhynchus crataegi; mature larva and mouthparts. 139 — dorsal view of head, 140 — labrum and clypeus, 141 — epipharynx, 142 — left mandible, 143 — 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., so — sensory organ.