Aphidius ericaphidis Pike & Starý, 2011

Pike, Keith S., Starý, Petr, Graf, George, Raworth, David A., Mathur, Sneh, Tanigoshi, Lynell K. & Murray, Todd, 2011, A new Aphidius Nees (Hymenoptera, Braconidae, Aphidiinae) of Ericaphis fimbriata (Richards) (Hemiptera, Aphididae) and key to parasitoids of blueberry aphid in the Pacific Northwest, Zootaxa 2802, pp. 58-62 : 59-60

Aphidius ericaphidis Pike & Starý , new species

( Figs 1 a–d, g)

Diagnosis. The female is characterized by a 15–16 segmented antenna, filiform (only slightly thickened to apex) with flagellomere placodes FI, FII, and FV = 0 (rarely 1, then only on one antenna), 1–2 (rarely 3), and 0–5 (rarely 6), respectively; forewing pterostigma length about 4.0 times width; R1 (= metacarpus) about half the length of the pterostigma; petiole costulate (7–10 costulae), length greater than 4 times width at spiracles; and aphid host predominately Ericaphis fimbriata . The most similar Aphidius is A. avenaphis (Fitch) , but the latter species is easily distinguished by non-overlapping differences in: 1) the number of antennal placodes [ A. avenaphis FI + FII + FV = 12.5 (range 9.5–14.0) vs. A. ericaphidis FI + FII + FV = 5.1 (range 3.0–8.0)], 2) pterostigma length / width ratio [ A. avenaphis = 3.0 (range 2.7–3.4) vs. A. ericaphidis = 3.9 (range 3.5–4.9)], and 3) pterostigma length / R1 forewing vein [ A. avenaphis = 1.4 (range 1.2–1.5) vs. A. ericaphidis = 2.1 (range 1.7–2.7)]. The range in antennal segments for A. avenaphis is 16–17, and hosts are commonly grass aphids such as Diuraphis noxia (Kurdjumov) , Rhopalosiphum padi (L.) and Sitobion avenae (F.) (see Liu 1977; Marsh 1979; Pike et al. 2000)]. To distinguish A. ericaphidis from other aphidiines that attack blueberry aphid, see key below.

Description. Female (n = 18). Body length 2.1 mm (range 2.0–2.2).

Head: width across eyes 0.44 mm (0.39–0.49); eye medium sized, length about 4.0 malar space, very sparsely setose; malar space slightly longer (1.1x) than tentorio-ocular line; tentorio-ocular line / intertentorial line 0.44 (0.34–0.55); clypeus twice as long as broad, with 7–11 long setae; maxillary palp 4–segmented and labial palp 3– segmented; antenna 15–16 segmented, filiform, very slightly thickened to apex; flagellomere 1 (= FI) length 2.9 (2.4–3.4) times width, setae equal two-thirds segment diameter, and usually without placodes (rarely 1, and then only on one antenna); FII length / width 2.9 (2.5–3.5); FIII length / width 2.4 (1.9–2.9); medial F and preapical F slightly broader than FII. Mesonotum: Notaulices distinct only anteriorly, effaced on disc but traced by two parallel irregular rows of sparse setae on each half until prescutellar groove. Legs: fore femur length 0.38 mm (0.36–0.39) with sparse long setae, the longest about half femur width; hind femur length 0.42 mm (0.39–0.43); fore tibia length 0.41 mm (0.39–0.42); hind tibia length 0.61 mm (0.55–0.63); hind tarsus I length 0.27 mm (0.23–0.30); hind tarsus II length 0.12 mm (0.10–0.13). Forewing ( Fig. 1 a): pterostigma length 0.45 mm (0.39–0.51), width 0.12 mm (0.09–0.13); R1 0.22 mm (0.18–0.26); r-rs 0.17 mm (0.14–0.21); r-m 0.08 mm (0.06–0.09); pterostigma length / width 3.92 (3.53–4.85), on average about 4x longer than wide; R1 / pterostigma 0.49 (0.38–0.58), on average about half as long as pterostigma; r-rs / pterostigma width 1.50 (1.15–1.87); R1 / pterostigma width 1.90 (1.45–2.33). Propodeum ( Figs 1 b–c): areolate, with narrow central areola which may be incomplete due to reduced bifurcation of the central carina. Propodeal setae on anterior half 9.5 (5.0–14.0), posterior half 5.9 (2.0–9.0). Metasoma: petiole length / width at spiracles 4.14 (3.82–4.50), surface partially rugose, with 7–10 costulae on anterolateral area ( Fig. 1 d); ovipositor sheath length less than 2.0 times width ( Fig. 1 g).

Color. Body variably brownish, typical of many Aphidius spp., with legs, petiole, and metasomal tergite II usually lighter.

Male. Similar to female, but with 17–18 antenna segments and generally slightly darker in color.

Field information. Aphidius ericaphidis and Praon unicum Smith were the two preeminent species parasitizing Ericaphis fimbriata in commercial blueberries in the Pacific Northwest. Pooled parasitoid rearing from sampled aphids across all sampled locations in southwestern British Columbia, eastern and western Washington, and northeastern Oregon, 2002–2009, showed 47.2% were A. ericaphidis , 44.6% were P. unicum . No other individual parasitoid species exceeded 3% of the pooled population. Seasonal occurrence of the active adults of the two species ran from April to November, with peak activity periods occurring between June and July.

Aphid hosts. Ericaphis fimbriata (main host), Macrosiphum parvifolii Richards (rare).

Etymology. The species is named after its main aphid host, Ericaphis fimbriata .

Distribution. The new species range extends from southern British Columbia to northeastern Oregon. Though not documented, it likely occurs further south through Oregon’s blueberry production areas.

Material examined. Holotype female (whole mount, dry): UNITED STATES, Oregon, Umatilla Co., Mill Cr., 8.VII.2005, 45.9888N 118.0934W, elevation 691 m, collector G. Graf (A5G069, deposited in USNM). Reared from Ericaphis fimbriata (Richards) on blueberry, Vaccinium corymbosum L. Paratypes [all reared from E. fimbriata on Vaccinium corymbosum and deposited in WSU unless indicated otherwise]: CANADA, British Columbia, Abbotsford, 9 & 23.VII.2002 (3f–A2D013, A2D021), 4 & 17.IX.2002 (3f, 1m –A2D031, A2D037), 17.IX.2003 (1f– A3D023); Cloverdale, 14.VI.2005 (3f, 1m –A5D013), 12 & 26.VII.2005 (2f, 1m –A5D022, A5D027); Mission, 21.VI.2005 (3f, 4m –A5D015, A5D016), 5 & 19.VII.2005 (31f, 42m –A5D019, A5D020, A5D024, A5D025 part in CNC, SCZ, USNM), 2.VIII.2005 (1f, 4m –A5D028), and 11.VII.2006 (1f, 1m –A6D063, A6D066); Pitt Meadows, 28.V.2002 (1f–A2D001), 25.VI.2002 (1f, 1m –A2D007), and 16.VII.2002 (3f, 1m –A2D019); Richmond, 16.VII.2002 (2f, 1m –A2D016 in SCZ), 1.VII.2003 (1f–A3D001), 14.VI.2005 (1f, 4m –A5D014 part in SCZ), and 12 & 26.VII.2005 (8f, 6m –A5D021, A5D026); UNITED STATES, Oregon, Umatilla Co., Mill Cr., 8.VII.2005 (34f, 21m –A5G069, part in CNC, SCZ, USNM), 29.VII.2005 (3f–A5G116), 1.IX.2005 (2f–A5G178), 21.X.2005 (1f, 1m –A5G234), and 5.VII.2006 (3f–A5G086); Washington, Clark Co., Vancouver, 25.VI.2005 (31f, 15m – A5L001, A5L002, A5L003); Columbia Co., Skyline Dr., 8.VII.2005, ex huckleberry Vaccinium membranaceum and V. sp. (2f–A5G073, A5G076) and 26.VII.2005, ex V. sp. (1f–A5G127); King Co., Bellevue, 18.V.2005, (2m – A5M805), 22.VI.2005 (4f, 5m –A5M805, A5M810), Skagit Co., Mt. Vernon, 10.VII.2009, (2f, 5m –A9L190); Yakima Co., Naches, 25.X.2005 (1f, 4m –A5G239), 25.VII.2006 (5f–A6G097), and Sunnyside, 25.IX.2008 (13f, 9m –A8G308).

Figures

FIGURE 1. Aphidius spp. parasitoids of the blueberry aphid. Aphidius ericaphidis sp. nov. (female): a, forewing; b – c, propodeum showing variation in carina; d, petiole; g, genitalia. Aphidius vaccinii (female): e, petiole. Aphidius ervi (female): f, petiole.