Apion brevicorne Gerstaecker, 1854

Lima, Rosana Maria de, Santos, Sandreli Berenice de Oliveira, Vaz, Stephanie, Gomes, Ana Laura Soares & Sousa, Wesley Oliveira de, 2020, Description of the larva and pupa of Apion brevicorne Gerstaecker, 1854 (Coleoptera: Brentidae: Apioninae) with biological information, Papéis Avulsos de Zoologia 60 (8), pp. 1-13 : 3-11

Apion brevicorne Gerstaecker, 1854

( Figs. 1-22 ; 29-35 )

Material examined: Brazil. Mato Grosso: Rondonópolis, Campus da Universidade Federal de Rondonópolis ( UFR), April to September 2018, host plant ( Copaifera malmei Harms ), 50 larvae (10 dissected, 9 metalized for SEM) ; 50 pupae, (9 metalized for SEM) ( DBFR) .

Mature larva description ( Figs. 1 , 10 ): Measurements (in mm): body length: 2.11-2.82, body width (metathorax): 1.30-1.50, head width: 0.66-0.76.

General: Body robust, sub-circular in cross-section, strongly dorso-ventrally curved (C-shaped); cuticle minutely spiculate, without visible pigmentation, areas sclerotized and devoid of roughness.

Colouration: Body distinctly white with copious white fat within; head capsule yellowish to pale brown.

Head ( Figs. 2-3 , 11 ): Slightly sclerotized; clypeus slightly darkened at the base, darkened labrum; epicranial line narrow with endocarina as an extension; frontal lines indistinct. Epicranium with 2 lateral setae (les), les1 shorter than les2. Dorsal epicranium with 3 setae (des 1, 3 and 5). Posterior epicranium with 2 tiny setae (pes). Frons with 4 setae (fs), fs2 and fs3 very short, fs4 medial and fs5 laterally positioned close to antennae. Ventral epicranium with 2 ventral setae (vcs), near les. Postoccipital condyles absent; tentorial bridge without anterior and posterior projections; hypopharyngeal bracon absent. Clypeus transverse, bearing 1 seta (cls), inner side of cls bearing 1 sensilla. Antenna ( Figs. 13-14 ) one-segmented, with rodlike accessory sensory appendage (acap) more than 3× as long as wide, with 2 spinose projections and 1 sensillum. Stemma (ocular spots) at the base of the antenna.

Mouthparts ( Figs. 4-9 , 12 ): Labrum ( Fig. 4 ) subtrapezoidal with lateral margins sinuose, with 3 setae (lms), lms2 three times longer than two remining setae. Epipharynx ( Fig. 5 ) with 2 long, stout lateral rods (lmR), 2 anterolateral setae (als), 2 anteromedian setae (ams), and 1 median seta (mes); epipharyngeal setae stout, short and apically rounded, lacking epipharyngeal sensory pores between pairs of lmR. Mandibles ( Fig. 6 ) symmetrical, apically bidentate, length and width approximately equal, cutting edge with 1 small, but evident, rounded tooth; laterodorsal surface with 2 mandibular setae (mds 1‑2), without sensilla.Maxilla ( Fig. 7 ): palpifer indistinct; maxillary palpi (MxP, Figs. 7-8 ) with 2 segments,basal segment with 1 long, basal accessory process, 1 short seta, apical segment cylindrical, apically flattened with dense crenulate setae; mala with 5 stout, short, indistinguishable setae dms‑vms; stipes (st) with 2 stipital setae (sts 1‑2), 1 basioventral seta (mbs) and 2 palpiferal setae (pfs 1‑2), cardo completely separated from stipes. Labium ( Fig. 9 ) subconical, preapically constricted and apically rounded, almost membranous except in sclerotized area (pmsc); labial palpus (lbP) vestigial, lobe-like. Premental sclerite (pmsc) distinctly dilated,“Y” shaped, with 1 pair of sensilla. Ligulate area with 1 tiny seta (lgs). Prementum (Prmt) with 1 seta (prms); postmentum (Pmt) with 3 setae (pms) laterally, pms2 (located medially) much longer than pms3 (located apically) which is somewhat longer than pms1 (located basally).

Thorax ( Fig. 1 ): Pronotal shield simple, without fold, unsclerotized; meso- and metanotum each with 2 folds (prodorsum and postdorsum). Spiracle ( Fig. 15 ) laterally intersegmental between pro- and mesothorax, bicameral. Prothoracic epipleura indistinct, meso- and metathoracic epipleura distinct,not centrally tuberculate,without setae. Pedal area defined, pedal lobe (papillae) present, 2-segmented. Pronotum with 2 setae (pns 1‑2), transversally aligned near to middle area; meso- and metanotum each with an 1 prodorsum (prs) and 1 postdorsum (pds) setae, epipleurum without setae; pedal area with 3 setae (pda); sternum with 1 tiny seta.

Abdomen ( Fig. 1 ): Tergites I-VII, each with 2 folds, prodorsum with 1 prs, postdorsum with 1 pds; tergite VIII undivided with 2 setae; tergite IX undivided and reduced with 2 setae; with 6 pairs of subequal bicameral spiracles, each pair anterolaterally on tergites I-VI, VII and VII without spiracles; pleura I-VIII without setae, each sternum with 1 seta. Anal area with 2 lobes and 1 seta.

Pupal description ( Figs. 16-21 ): Measurements (in mm): body length: 3.00-4.13, body width (metathorax): 1.22-1.50.

General: Adecticous and exarate; body setae on tubercles, setae greatly reduced in number and size.

Colouration: Inner body pure white, except eyes, which are pale to dark.

Rostrum in ventral view ( Figs. 16 , 22 ): Apex extends past mesocoxae but not to metacoxae, mesorostrum dilated, mandibular theca projected; 1 distirostral seta (drs).

Head: Frons with 1 seta (os), similar in size as drs, behind eyes. Antennae basally near prosternum and apically extend to propleura, oblique to protibia.

Thorax: In dorsal view, pronotum with 1 apical pronotal seta (aps), 2 lateral pronotal setae (lps 1‑2), and 1 discal pronotal seta (dps2); in ventral view, aps and lps 1‑2 completely visible. Mesonotum without setae; metanotum with 1 seta (mtns). Legs ( Figs. 16-21 ): in ventral view, metatibiae and femora covered by pterothecae, front and middle legs and metatarsomere visible; pro-, meso- and metafemora apically bearing 1 slightly outcurved seta (fes), each seta inserted in a small rounded protuberance.

Abdomen: In ventral view, ventrites IV-IX visible ( Fig. 16 ), in dorsal view tergites I-VII about equal in length and decreasing in width ( Fig.17 ),segmentsVII-IX clearly and gradually reduced;5 spiracles present,positioned on pleura I-V, bicameral ( Fig. 18 );pseudocerci inconspicuous at segment IX, unpigmented; in ventral view, ventrites IV-VIII with 1 pair of setae; in dorsal view,tergites I-IX without setae.

Sexual dimorphism: Female with small round convexity on each side of sternum on ninth abdominal segment ( Figs. 16 , 22 ).

Biological information ( Figs. 23-28 ): Apion brevicorne is associated with C. malmei . Adults may feed on nectar in flowers at any time, day or night. Copulation and oviposition occur on fruits at any stage of development. The oviposition is endophytic and eggs are easily found only in fruits at an early stage of development.As in most weevils, the damage caused by A. brevicorne to the seed is mostly by larvae that develop within the seed, where they feed on developing endocarp. Pupae were always found within seeds (without a pupal chamber) along with feces that indicate that the larvae consumed the entire endocarp,and so development is completed within the seed. The number of adults in each seed is quite variable. Seed pods that contain larvae, pupae or adults show no external evidence of presence. This suggests that for adults to disperse, they depend on the dry dehiscence of the fruit. Dead adults and pupae can be found within dry seed pods that did not dehisce.

Figures

Figures 1-3.ApionbrevicorneGerstaecker,last instarlarva:(1) habitus,lateral;(2) headcapsule,frontal;(3) headcapsule,ventral.Abbreviations:[seta(ae)-s.]:des= dorsal epicranial s.; es = epicranial suture;fs = frontal epicranial s.; les = lateral epicranial s.; pes= posterior epicranial s.;pns = pronotal s.; prs = prodorsal s.;vcs = ventral epicranials s.

Figures 4-9.Apionbrevicorne Gerstaecker,mouthparts:(4)clypeus andlabrum,dorsal;(5)epipharynx;(6)mandible,dorsal;(7)maxilla;(8)maxillarypalp;(9) labium. Abbreviations:[seta(ae)-s.]:ams =anteromedianepipharyngeals.;als=anterolateralepipharyngeal s.;cls=clypeals.;dms =dorsalmalar s.;lbp= labialpalp;lmr= labral rods;lgs = ligular s.;lms = labral s.;mbs = basioventral seta s.;mes = medianepipharyngeal s.;mds = mandibular s.; mxp = maxillary palp;pmt = postmentum;pms = postmentals.;prmt= prementum;prms = prementals.;pmsc= premental sclerite;pfs =palpiferal s.;st = stipes;sts = stipital s.;vms = ventral malar s.

Figures 10-15. Apion brevicorne Gerstaecker,SEM micrographs larva:(10) habitus,lateral;(11) head,frontal; (12) mouthparts,frontal;(13-14) antenna;(15) spiracle.Legend:Acap = accessory sensory appendage.

Figures 16-18.Apionbrevicorne Gerstaecker,femalepupal habitus:(16)ventral;(17)dorsal;(18) lateral.Abbreviations:[seta (ae)-s]:aps= apicalpronotal s.;dps= discal pronotal s.; drs = distirostral s.; dps = discal pronotal s.; fes = femorals.;lps = lateral pronotal s.;mtns = metanotal s.;os = orbital s.

Figures 19-22. Apion brevicorne Gerstaecker, SEM micrographs pupa: (19-21) habitus: (19) ventral; (20) dorsal; (21) lateral; (22) female, abdominal segments VII-IX,ventral.

Figures 29-35. Apion brevicorne Gerstaecker:(29-30) habitus lateral,male, female;(31, 32) male pygidium,dorsal,lateral;(33) tegmen dorsal;(34) penis lateral; (35) spiculum gastrale.

Figures 23-28. Copaifera malmei host plant of the Apion brevicorne: (23) host plant habitus; (24) fruit in intermediate stages of development; (25) mature fruit in dehiscence stage;(26)A. brevicorne feeding on floral nectar;(27)attacked fruit and (28)healthy fruit.