Aleiodes albitibia ( Herrich-Schaeffer , 1838)

van Achterberg, Cornelis & Shaw, Mark R., 2016, Revision of the western Palaearctic species of Aleiodes Wesmael (Hymenoptera, Braconidae, Rogadinae). Part 1: Introduction, key to species groups, outlying distinctive species, and revisionary notes on some further species, ZooKeys 639, pp. 1-164 : 34-36

Aleiodes albitibia ( Herrich-Schaeffer, 1838) Figs 20-21, 22-34

Rogas albitibia Herrich-Schäffer, [April] 1838: 156; Shenefelt 1975: 1217; van Achterberg 1991: 24 (as senior synonym of Aleiodes heterogaster ).

Aleiodes albitibia ; van Achterberg 1991: 24; Belokobylskij et al. 2003: 398.

Aleiodes heterogaster Wesmael, [May] 1838: 96; Shenefelt 1975: 1176; Papp 1991: 97 (examined).

Rhogas heterogaster ; Fahringer 1932: 258-259.

Rogas heterogaster ; Hammond and Smith 1957: 181; Tobias 1986: 82 (transl.: 136).

Type material.

Redescribed ♀ and holotype of Aleiodes heterogaster (KBIN), "[Belgium], Campine, 1833", " Aleiodes heterogaster mihi, det. C. Wesmael", "Belgique, Charleroi/teste Papp, J., 1983", "Holotypus Aleiodes heterogaster Wesm., 1838 / Papp, 1983". The type series of Rogas albitibia is lost.

Additional material.

*Austria, British Isles (England: V.C.s 3, 11, 15, 22, 58, 59, 61, 69; Wales: V.C. 49; Scotland: V.C.s 72, 77, 80, 88, 92, 96, 97, 98, 99; Ireland: (V.C.s H1, H19, H20), *Czech Republic, Finland, France, Germany, Hungary, Netherlands (DR: Wijster, LI: Asselt; Castelre, GE: Heerde; Putten; Tongeren, NB: Tilburg (Kaaistoep), NH: Muiderberg, OV: Buurse (Schipbeek)), Poland, *Spain, Sweden, Switzerland. Specimens in NMS, BMNH, BZL, CNC, OUM, RMNH, SDEI, USNM, ZSSM, I. Kakko collection, and WUIM.

Molecular data.

MRS210 (Scotland EU979574, CO1), MRS383 (Sweden JF962835/ KU682238, CO1), MRS753 (Sweden KU682248, CO1).

Biology.

Univoltine parasitoid of arboreal notodontids, overwintering in a highly distinctive mummy (Fig. 21). Specimens (in NMS unless indicated) reared from wild collected arboreal Notodontidae identified as Notodonta dromedarius (Linnaeus) (12 [5 are OUM, 2 are USNM]; T.H. Ford, M.J. Morgan, M.R. Shaw, A.W. Stelfox, W.A. Watson), Eligmodonta ziczac (Linneaus) (2:1; M.R. Shaw), Pheosia tremula (Clerck) (8 [1 is AAC]; A.A. Allen, B.T. Parsons, M.R. Shaw), Pheosia gnoma (Fabricius) (2 [BMNH]; G. Graham-Smith). Host range experiments had the following outcomes: Eligmodonta ziczac 2:32\10\\8+2; Pterostoma palpina (Clerck) 2:10\0\\-; Ptilodon capucina (Linnaeus) 1:5\0\\-; Clostera pigra (Hufnagel) 2:9\0\\-; Phalera bucephala (Linnaeus) 2:2\0\\-. The developmental biology of this species is rather unusual in several respects. On approaching the host ( Eligmodonta ziczac in all the following observations, which are based on two female Aleiodes albitibia ) the female seems to depend on its fore and middle tarsi more than its antennae for host assessment, although antennation does occur (possibly as much to desensitise the host as to investigate it). The host is not paralysed during attack: the female more or less pounces on the host once accepted and aligns herself along the host’s body, which she grasps with her front and middle legs during oviposition, and fans her wings for short bursts repeatedly during the oviposition process (this may have indicated that venom was being injected, but if so it did not appear to have a significantly paralysing action), which in some cases lasted as long as 10-15 minutes - in these cases usually with more than one insertion. In fact, probably because the host was not temporarily parasitised and so was not sluggish, self-superparasitism happened very easily. The metasoma is only weakly curled downwards during oviposition, after which the female left the host without the usual post-oviposition period of association. When young, the females host-fed non-destructively on occasion. Development of the parasitoid larva was extremely rapid at ca 22-25 °C, with mummification ensuing after as few as 7-10 days from oviposition. The unusual and highly distinctive mummy (Fig. 21) is very shiny and dark mahogany brown in colour. It consists of the caudal portion of the host (usually from abdominal segment 3 onwards), strongly delimited from the anterior portion which usually shrivels up and becomes detached, leaving a sharp rim. The parasitoid pupates in a capsule which is formed in the most caudal half of this structure (usually in abdominal segments 5-8), dorsally raised, thinly lined with silk, and sealed from a more ventral and anterior inflation of the host’s cuticle that is of approximately equal volume but fully open at its anterior end. During the mummification process this area fills with liquid and bubbles, but fluids do not spread to the substrate and the mummy does not become stuck down. Once dried and hardened, the whole structure looks as though it contains two pupating parasitoids, and indeed some authors have been misled by this ( Hammond and Smith 1957). It is possible that the empty chamber may serve to decoy pseudo-hyperparasitoids, though this seems unlikely to be its main function. The mummy forms on the host’s food plant, usually on a leaf surface from which it is easily dislodged, and overwinters in the leaf litter. Aleiodes albitibia occurs particularly in wet, bushy places: bearing in mind that its hosts (evidently rather restricted within Notodontidae ) feed on trees and shrubs ( Salix , Populus , Alnus and Betula ) that often overhang water, the form of the mummy may also be an adaptation to prevent submersion and perhaps also results in dispersion by water, as it floats easily and is not wetted. The winter is passed in the mummy, and Aleiodes albitibia is univoltine, with a flight period in Britain of roughly JuneAugust.

Diagnosis.

Third antennal segment robust (Fig. 34); area in front of anterior ocellus without tubercle; OOL 0.4-0.5 × diameter of posterior ocellus (Fig. 32); mesopleuron strongly shiny and precoxal area not impressed (Fig. 24); pterostigma dark brown; vein 1r-m of hind wing about as long as vein 1-M (Fig. 23); inner hind tibial spur 0.4-0.5 × hind basitarsus; inner side of basal half of hind tibia whitish, rarely largely dark brown; inner side of hind tibia with bristly setae and no comb apically; third tergite curved medio-posteriorly in dorsal view (Fig. 25) and longer than second; metasomal tergites largely black (also laterally so), sometimes with a large yellow or ivory central patch on second tergite.

Description.

Holotype of Aleiodes heterogaster , length of fore wing 5.4 mm, of body 5.6 mm.

Head. Antennal segments of ♀ 46, long setose, length of antenna 1.2 × fore wing, its subapical segments distinctly longer than wide; frons weakly depressed, finely rugose medially, remainder superficially micro-granulate; OOL 0.4 × diameter of posterior ocellus, and finely granulate; vertex finely granulate, with some rugulae posteriorly, rather dull; clypeus normal, micro-granulate; ventral margin of clypeus thick and not protruding forwards; width of hypoclypeal depression 0.5 × minimum width of face (Fig. 29); length of eye 2.8 × temple in dorsal view (Fig. 32); occiput behind stemmaticum granulate with some rugulae, narrow; clypeus near lower level of eyes; length of malar space 0.2 × length of eye in lateral view; occipital carina widely interrupted medio-dorsally and ventrally (Fig. 30).

Mesosoma. Mesoscutal lobes largely granulate and with punctulation, matt; prepectal carina complete, rather weak; precoxal area of mesopleuron largely smooth (but in other specimens usually micro-granulate with some punctulation); mesopleuron above precoxal area strongly shiny and smooth; metapleuron largely coriaceous; scutellum granulate and finely punctate, no distinct carina; propodeum evenly convex, short, anteriorly granulate, medially and posteriorly rugose, median carina complete, without tubercles.

Wings. Fore wing: r 0.5 × 3-SR (Fig. 22); 1-CU1 horizontal, 0.35 × 2-CU1; r-m 0.5 × 3-SR; second submarginal cell rather long (Fig. 22); cu-a inclivous, curved posteriorly; 1-M straight posteriorly. Hind wing: marginal cell subparallel-sided, its apical width 1.0 × width at level of hamuli (Fig. 23); 2-SC+R shortly longitudinal (but in other specimens subquadrate); m-cu absent; M+CU:1-M = 5:3; 1r-m about as long as 1-M.

Legs. Tarsal claws yellowish setose; hind coxa sparsely punctulate, and granulate; hind trochantellus robust; length of fore femur, hind femur and basitarsus 5.4, 3.7 and 6.6 × their width, respectively (Figs 26, 28); length of inner hind spur 0.5 × hind basitarsus, as long as outer spur.

Metasoma. First tergite robust (Fig. 25); first and second tergites rather coarsely longitudinally (reticulate-)rugose, robust, with distinct median carina; medio-basal area of second tergite minute, triangular; second suture shallow; third tergite as long as second tergite and largely granulate, anteriorly with some rugulae; remainder of metasoma smooth, compressed; fourth and apical half of third tergite without sharp lateral crease; ovipositor sheath slender and rather shiny.

Colour. Black; malar area, narrow stripe along eyes dorsally, fore and middle legs (but telotarsi infuscate), hind coxa, trochanter trochantellus and femur, palpi and teg ulae yellowish; pterostigma and most veins dark brown; basal 0.6 of hind tibia ivory; remainder of hind tibia and tarsus blackish.

Variation. Antennal segments of ♀: 43(8), 44(14), 45(14), 46(3), 47(3), 49(1); of ♂: 39(1), 40(7), 41(7), 42(4), 43(3), 44(2). Second metasomal tergite may be largely yellowish or ivory (except laterally), or only with pale basal patch; hind tibia may be largely dark brown; base of pterostigma and first tergite medio-apically completely black (typical Aleiodes heterogaster ) or yellowish (typical Aleiodes albitibia ); width of hypoclypeal depression 0.4-0.5 × minimum width of face; mesopleuron usually with faint brownish longitudinal streak ventrally.

Notes.

Males average about four fewer antennal segments than females. As is the case for the vast majority of Aleiodes species, only one parasitoid develops in each host (pace Hammond and Smith 1957).