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
Author
Rafał Gosik
Author
Peter Sprick
Author
Jiří Skuhrovec
Author
Magdalena Deruś
Author
Martin Hommes
text
Zootaxa
2016
4108
1
1
67
journal article
39126
10.11646/zootaxa.4108.1.1
015bce14-fc37-4afb-b997-4b1e974770f9
1175-5326
265725
B802F2B1-944E-4B84-A856-8091E60D88FC
Otiorhynchus
(
Pendragon
)
ovatus
(Linnaeus, 1758)
Material examined:
16 larvae
(
Fig. 217
). JKI, Braunschweig, climate chamber, breeding in flowerpots with frigo strawberries (
Fragaria
x
ananassa
(West.) Duch. ex Roz.) and
Fragaria vesca
cultivar ‘Regina’,
13.12.2012
, 2 ex.;
10.01.2013
, 1 ex.;
29.04.2013
, 4 ex.; 0 5.05.2013, 3 ex.;
19.05.2013
, 3 ex.;
27.05.2013
, 1 ex.
Remarks about breeding and development.
All larvae used for the description were obtained from at least 1 breeding effort in the climate chamber of JKI. In 2011 only a few adults were released on 2 flowerpots with
Euonymus fortunei
and
Fragaria vesca
. The results were unsatisfactory as only
Otiorhynchus sulcatus
was obtained. In 2012 breeding was started at 2 dates in
May 2012
and at one date in July. 8 weevils were released on 14.05. and 24.05. on 2 flowerpots with frigo strawberries and 2 with
Fragaria vesca
; on
25.07.
36
adult specimens and 1 flowerpot with
Fragaria vesca
and 5 pots with frigo strawberries were added to the breeding cage. The first mature larvae were taken out on
13.12.2012
, but may have developed earlier, as on 0 1.11. this breeding had not been controlled. On
14.03.2013
1 flowerpot with many larvae was taken to Hannover for regular pupae control and revealed
1 pupa
on
27.05.2013
. Afterwards this breeding attempt was terminated.
In the field larvae of
Otiorhynchus ovatus
were found more or less by chance: 1 mature larva was collected on
29.03.
2011
in Bad Zwischenahn under
Thuja occidentalis
cultivar ‘Smaragd’ and revealed an adult weevil already on
26.04.2011
. The pupa was seen first on 18.04., but the exact date of pupation is unknown.
The life-cycle of this species is rather well-known and was studied by
Treherne (1914)
,
Spessivtseff (1923)
,
Wilcox
et al.
(1934)
and
Stein & Küthe (1969)
in different regions and at different occasions.
Treherne (1914)
published the first life table, and
Spessivtseff (1923)
was the first who gave a detailed description of the larva. According to
Treherne (1914)
eggs were laid from mid-June to end of August, and larvae develop from late summer to spring, with a dormant period in winter, pupate from April to June, and young, at first light brownish adults emerge mainly in June and July on the soil surface. Usually adults die when the oviposition period is over, but according to
Wilcox
et al.
(1934)
, at higher elevations a significant proportion overwinters and starts to lay eggs early in the season (in May). This widespread species is described as harmful in strawberry plantations (“Strawberry Root Weevil”) as well as in young conifer plantings.
Description
(
Figs. 122–132
).
Coloration
. Head light yellow; all thoracic and abdominal segments from white to yellowish; body covered with very fine cuticular processes.
FIGURES 122–127
.
Otiorhynchus ovatus
; mature larva. 122—habitus, lateral view, 123—lateral view of thoracic segments, 124—lateral view of abdominal segment I, 125—lateral view of abdominal segments VIII–IX, 126—ventral view of abdominal segments VIII–X, 127—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 128–132.
Otiorhynchus ovatus
; mature larva and mouthparts. 128—dorsal view of head, 129—labrum and clypeus, 130—epipharynx, 131—left mandible, 132—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.
Body
elongated (
Fig. 122
).
Chaetotaxy
: Setae different in length, relatively long, filiform; white to yellow.
Thorax
. Prothorax with 4 long and 6 medium long to short
prns
; and 2
ps,
different in length. Mesothorax with 1 medium long
prs
; 5
pds
(ordered: 1 long, 1 minute, 1 very long, 1 long and 1 very long); 1 long
as
(sometimes with an additional microseta); 1 long
eps
; and 1 long
ps
. Chaetotaxy of meso- and metathorax similar. Each pedal area of thoracic segments well isolated, with 5
pda,
different in length. Each thoracic segment with 1 short
eus
(
Fig. 123
).
Abdomen
. Abdominal segments I–VIII with 1 short
prs
; 5
pds
(ordered: 1 long, 1 short, 1 long, 1 short and 1 long); 1 long and 1 minute
sps
[abd. seg. VIII without
sps
]; 2
eps,
different in length; 1 long and 1 medium long
ps
; 1 medium long
lsts
; and 2
eus
(
Figs. 124, 126, 127
). Abdominal segment IX with 3
ds
, different in length; 1
ps
very long; and 2
sts,
equal in length (
Figs. 125–127
). Lateral lobes of abdominal segment X with 2 minute
ts
each.
Head
subglobose, narrowed bilaterally (
Fig. 128
). 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
. Postepicranial area with a group of 2 pairs of sensilla, and frons with 2 pairs of sensilla. Stemmata (2 pairs) feebly visible. Antennal segment membranous, bearing 1 conical sensorium and 4–5 filiform sensilla.
Clypeus
2.7 times as wide as long with 1 very short
cls
, placed posterolaterally (
Fig. 129
).
Labrum
about 2 times as wide as long with 3 long, straight
lms
of different length, placed medially or mediolaterally;
lms
2 shorter than other setae, all
lms
exceeding the outline of the labrum; the anterior margin of labrum rounded (
Fig. 129
).
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, parallel (
Fig. 130
).
Mandible
(
Fig. 131
) feebly bifid, teeth almost of equal height; with 2
mds,
different in length; internal edge with small triangular teeth.
Maxilla
(
Fig. 132
) with 1 very long
stps
and 2 very long
pfs
, placed ventrolaterally; 1 very short
mbs
, situated ventrally. Mala with 5
dms,
different in length and 4 straight
vms
, different in length. Maxillary palpi with two palpomeres; basal palpomere wider than distal; 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. 132
), with 2 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
pms
3 (
Fig. 132
).
Differential diagnosis
. See “Key to larvae of selected
Otiorhynchus
species” and
Tables 1
,
2
.