Selitrichodes neseri n. sp., a new parasitoid of the eucalyptus gall wasp Leptocybe invasa Fisher & La Salle (Hymenoptera: Eulophidae: Tetrastichinae)
Author
Kelly, Janine
Author
Salle, John La
Author
Harney, Marlene
Author
Dittrich-Schröder, Gudrun
Author
Hurley, Brett
text
Zootaxa
2012
3333
50
57
journal article
10.5281/zenodo.213853
ea92dde8-668c-41e7-8209-2db71a14667e
1175-5326
213853
Selitrichodes neseri
Kelly & La Salle
,
sp. nov.
Figs 2–11
Diagnosis
.
Selitrichodes neseri
is the only known species of
Selitrichodes
with a distinctly infumated patch behind the marginal vein (
Fig. 7
). Other diagnostic characters are forewing with 2 setae on submarginal vein and head and body almost entirely dark brown to black without yellow markings, except for the male where the face is yellow.
FIGURES 3–8
.
Selitrichodes neseri
female:
3
, dosolateral habitus;
4
, head in frontal view;
5
, antenna in lateral view;
6
,
mesosoma
in dorsal view;
7
, wing in dorsal view;
8
, metasoma in dorsal view.
FIGURES 9–11
. 9 and 10,
Selitrichodes neseri
male:
9
, dosolateral habitus;
10
, antenna in lateral view.
11
,
Selitrichodes neseri
eggs on a pupa of
Leptocybe invasa
(more than one egg probably a cage artefact) (Photo: Stefan Neser).
Description.
Female
(
Figs 2–8
). Length
0.87–1.08 mm
. Head black. Antenna with scape dark brown (may be lighter apically); flagellum brown.
Mesosoma
black; gaster dark brown. Coxae black (may be lighter apically); trochanters dark brown; femora dark brown to black; fore and middle tibiae light brown to yellow; hind tibia dark brown with apical third brown to yellow.
Head
(
Fig. 4
). Ocellar triangle without grooves. POL about 2.5 times as long as OOL. Scrobal area without distinct median carina; with a small transverse crack-like suture about halfway between frontal suture and torulus. Torulus level with ventral margin of eye. A broad depression (supraclypeal area) below torulus extending to clypeus and with some pilosity. Gena swollen and with malar sulcus somewhat curved near mouth margin. Clypeal margin bidentate.
Antenna
(
Fig. 5
) with 2 anelli, 3 funicular and 3 claval segments. First anellus longer than second. First and second funicular segments slightly longer than wide (F1 1.13–1.38; F2 2.00–1.38), third slightly wider than long to subquadrate (F3 0.90–1.2). Relative length of funicular segments to pedicel as follows: PDL: F1: F2: F3 = 1: 0.50–0.64: 0.55–0.60: 0.43–0.65. Clava 1.90–2.58 times longer than wide, wider than funicle, with terminal spine; C3 very short and its end broad, tapering slightly apically. Scape slightly flattened.
Mesosoma
(
Fig. 6
). Pronotum very short medially in dorsal view. Midlobe of mesoscutum with one row of 5 adnotaular setae on each side (some setae may form a partial second row). Scutellum with anterior pair of setae located behind middle. Dorsellum rounded posteriorly and overhanging propodeum. Mesosternum convex just in front of trochantinal lobes and without precoxal suture. Propodeum in dorsal view medially shorter than dorsellum. Propodeal spiracle with entire rim exposed and separated from anterior margin of propodeum by less than its largest diameter; rim of spiracle with a seta (seta of left spiracle broken in
Fig. 6
). Paraspiracular carina absent. Callus with 0 or 1 seta.
Forewing
(
Fig. 7
). Hyaline, with a distinct infumated patch behind marginal vein. Submarginal vein with 2 dorsal setae. Costal cell with one or more setae and a line of ventral setae near apex. Relative length of wing veins to stigmal vein as follows: CC: MV: STV: PMV = 2.83–4.33: 3.08–4.78: 1: 0.33–0.45: PMV one-third to just less than one-half length of stigmal vein. Speculum small and open posteriorly, the cubital line of setae not extending to basal line; speculum with one or more setae dorsally and with one to a few small setae on underside of wing. Wing disk beyond speculum densely pilose.
Metasoma
(
Fig. 8
). Gaster distinctly longer (1.56–1.66 times) than
mesosoma
. Hypopygium reaching less than half length of gaster. Cercus with 3 setae, subequal in length and slightly curved. Ovipositor sheath slightly protruding, short in dorsal view.
Male
(
Figs 9, 10
). Length
0.65–0.73 mm
. Head dark brown to black, with yellow markings on lower face generally extending dorsally from mouth margin beyond toruli for about half distance to anterior ocellus, and laterally to inner eye margin and not reaching malar sulcus except in lighter specimens sometimes extending beyond malar sulcus onto gena. Antennae light yellow to white, funicle darker in some specimens. Legs light yellow to white, except for darker femora.
Mesosoma
and gaster dark brown to black, with base of gaster lighter. Gastral petiole very light yellow to white.
Antenna
(
Fig. 10
) with 2 anelli, 3 funicular and 3 claval segments. F1 and F2 quadrate to slightly longer than wide, F3 wider than long, with each successive segment increasingly broader. Funicle and clava without compact subbasal whorls of long setae. Scape with ventral plaque less than one-quarter length of and situated near apex of scape.
Material Examined.
Holotype
female (
ANIC
): Laboratory reared at the Agricultural Research Council, Plant Protection Research Institute, emerged in culture
x.2010
(originally from
Australia
, Queensland, Nanango, S.
26º41’19.3”S
; E.
151º59’02.75”E
, S. Neser, ex. leaf, petiole and twig galls on
Eucalyptus
sp.,
ix 2010
).
49Ψ 115ɗ
paratypes
. Same data as
holotype
(49Ψ 54ɗ as follows: 17Ψ 24ɗ
ANIC
; 17Ψ 15ɗ
SANC
; 5Ψ 5ɗ
BMNH
; 5Ψ 5ɗ
USNM
; 5Ψ 5ɗ
QMB
); same data as
holotype
except emerged in culture
ix.2010
(61ɗ
ANIC
).
Etymology.
Named in honour of Stefan Neser, who first collected the species and provided valuable information on its biology.
Notes on biology.
Specimens of
S
.
neseri
were exposed to ungalled
Eucalyptus grandis
x
Eucalyptus camaldulensis
(hybrid/clone number: GC540) potted plants to determine their possible role as a gall former or primary parasitoid. Unlike its congener
S. globulus
(
La Salle
et al.
2009
)
, it was confirmed that
S. neseri
is not a gall former.
Selitrichodes neseri
were reared on galled
E. grandis
x
E. camaldulensis
(GC540) potted plants in the FABI quarantine facility at an average room temperature of 26º C. Males and females were released into a sleeve enclosing the galled branches and leaves, and honey paper added to the sleeves to extend the longevity of adults. Galls exposed to
S. neseri
contained mature larvae or pupae of
L. invasa
. The sleeves were removed and the branches cut shortly before the anticipated emergence of the
S. neseri
offspring. Plant material was subsequently placed in large, unventilated polyethylene containers (“cake savers”) to allow monitoring of emerging specimens. Developmental time in the laboratory (egg-to-egg) ranged from 18–30 days.
Selitrichodes neseri
can be successfully reared under laboratory conditions, even in mature galls on severed shoots (Stefan Neser, pers com.), as is evident by the number of generations (10) and large numbers of adults reared within the first year. Dissections of
L. invasa
galls exposed to
S. neseri
showed single, relatively large eggs present externally on mature
L. invasa
larvae or pupae (
Fig. 11
), as well as
S. neseri
larvae feeding on mature
L. invasa
larvae and pupae. This indicated that
S. neseri
is a primary parasitoid of
L. invasa
and not an inquiline.
Galls induced by
Quadrastichus gallicola
Prinsloo & Kelly
on
Erythrina lysistemon
(Fabaceae)
resemble galls of
L. invasa
, but were not found to be suitable for oviposition by
S. neseri
. More detailed studies of the biology and host range of
S. neseri
are underway.
The biological control of
L. invasa
has to remain a priority for all countries involved in the commercial production of susceptible species of
Eucalyptus
.
Selitrichodes neseri
is an additional parasitoid that shows much promise for biological control of this pest.