Plant host affiliation and redescription of Phytomyza subtenella frost (Diptera: Agromyzidae)

2004·3.3 MB·

by  Stephen D Gaimari

PROC. ENTOMOL. SOC. WASH.
106(3), 2004, pp. 501-507
PLANT HOST AFFILIATION AND REDESCRIPTION OF
PHYTOMYZA SVBTENELLA FROST (DIPTERA: AGROMYZIDAE)
Stephen D. Gaimari, Lynn S. Adler, and Sonja J. Scheffer
(SDG) California State Collection of Arthropods, California Department of Food and
—
Agriculture Plant Pest Diagnostics. 3294 Meadowview Road, Sacramento, CA 95832-
1448, USA, (e-mail: [email protected]); (LSA) Department of Biology, 21 19 Derring
Hall, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061. USA,
(e-mail: [email protected]); (SJS) Systematic Entomology Laboratory. PSI, Agricultural Re-
search Service, U.S. Department of Agriculture, Building 005, BARC-West, 10300 Bal-
MD
timore Ave., Beltsville, 20705, USA, (e-mail: [email protected])
—
Abstract. The biology of Phytomyza subtenella Frost (Diptera: Agromyzidae) was
observed for the first time. This species was found to be a seed feeder on the hemiparasitic
Indian paintbrush, Castilleja miniata Douglas (Orobanchaceae), in Colorado. Biological
observations are provided, along with a redescription of the species and illustrations of
the male genitalia. Additionally, the 17 orobanch-feeding agromyzids are discussed, along
with comments on several possible lineages, based on similarities of male genitalia, within
the 13 orobanch-feeding Phytomyza.
Key Words: Agromyzidae, Phytomyza subteneUa, Orobanchaceae, Castilleja miniata,
host plant
The agromyzid genus Phytomyza Fallen groups of highly specialized insects (Eh-
contains more than 450 described species, rilch and Raven 1964, Becerra 1997, Farrell
all of which have internally feeding, plant- 1998, Becerra and Venable 1999), although
parasitic larvae (Spencer and Steyskal the processes giving rise to such patterns
A
1986). Most species of Phytomyza are leaf- are not fully understood. critical first step
miners, but some are known to feed in other in investigating either the patterns or pro-
plant parts, including stems, roots, flowers, cesses involved with insect diversification
and seeds. Members of this genus attack is gaining a clear understanding of the host
species in nearly 30 plant families, although affiliations of the species of interest.
most individual Phytomyza species are Agromyzid species attacking leaves gen-
highly restricted in diet, usually monopha- erally form an externally visible tunnel or
gous or feeding on few closely related plant "leafmine" as they feed, making them con-
species (Spencer 1990, Scheffer and Wieg- spicuous to entomologists. In contrast,
mann 2000). Within Phytomyza. morpho- those species that feed deeply within tissues
logically similar species tend to feed on such as stems, roots, flowers, or fruits often
closely related plants (those in the same ge- provide no external symptom of their pres-
nus or family) in a pattern suggestive of ence. These species are not readily discov-
host-associated radiations (e.g., Scheffer ered without targeted collection followed
and Wiegmann 2000). This type of pattern by dissection of plants. Npt surprisingly,
has been discussed for a number of other our knowledge of such species and their
502 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
'\
SS
Figs. 1-4. Phytoinyza siibtenella, S genitalia; scale bar = 0.1 mm; aa = aedeagal apodeme, bp = basiphallus,
h = hypandrium. p = paramere, sd = sperm duct, ss = surstylus. 1, Epandrial complex, dorsal view. 2. Aedeagal
complex, lateral view. 3, Ejaculatory apodeme, lateral view. 4, Distiphallus, ventral view.
host affiliations is fragmentary, limiting our Methods and Results
ability to fully investigate host-use evolu-
Morphological terminology follows
tion within Agromyzidae.
McAlpine (1981) and Spencer (1987).
Although most Phytomyza species are
Voucher specimens of the flies have been
leafminers, a number are known to feed in
labeled as such and deposited in the Cali-
stems or seeds (Spencer 1990), including
fornia State Collection of Arthropods
one group of primarily seed feeders that has (CSCA) in Sacramento, CA, and the Na-
apparently radiated onto plants in the Oro- tional Museum of Natural History (USNM)
banchaceae. Currently, in North America
in Washington, DC; voucher specimens of
and Europe, there are 3 Phytomyza species
1 the plants (LSA#1, 3, 5) have been depos-
known from this plant family (Table 1). Al- ited in the Herbarium of the Rocky Moun-
though phylogenetic relationships among
tain Biological Laboratory, Gothic, CO.
these and other Phytomyza species have not
In late summer 1996, numerous fly pu-
been explored, genitalic similarities suggest C
paria were observed in fruits of miniata
that there are several distinct lineages with- (voucher specimen LSA #3) at Emerald
in this group, with unknown affinities
Lake, Colorado. Pupae were collected from
among these lineages.
these fruits in September and were stored
Spencer (1969) first alluded to the pos- in 1 oz. plastic portion cups, half at room
sibility that Phytomyza subtenella Frost is a temperature and half in a 0°C freezer in an
seed (or stem) feeder, citing the elongated
attempt to simulate overwintering condi-
form of the ovipositor, and later comment-
tions. Adult emergence by either method
ing that it is "almost certainly an internal was low (<5% of —200 puparia), possibly
feeder" (Spencer 1981). Here, we report the
due to the change in microclimate by re-
host plant for this species, having reared it moval from the field. In July of the follow-
from a hemiparasitic Indian paintbrush.
ing year, adult flies were collected from the
Castilleja miniata Douglas (Orobancha-
bracts of C. miniata.
We
ceae). also report observations on its
natural history and provide a redescription Taxonomy
and more detailed drawings of genitalia
Phytomyza subtenella Frost
than were previously available in the liter-
(Figs. 1-4)
ature (only the basiphallus had been figured
thus far, cf. Spencer and Steyskal 1986: Phytomyza subtenella Frost 1924: 89. Type
figs. 1148, 1149). locality: "Mount Rainier (Washington)".
X
VOLUME NUMBER
106. 3 503
Type: LT9 in USNM (designated by brown, and first flagellomere and arista
Flick 1959, by assumption of holotype). black. Postocellar setae strong, divergent.
Subsequent references: Frick 1952: 428 Ocellar setae proclinate, as strong as pos-
(catalog); Frick 1959: 436 (inadvertent terior orbital setae, with bases same dis-
lectotype designation, diagnosis, illustra- tance apart as posterior ocelli. Frons 1.5-
tions of head and wing); Frick 1965: 805 2.Ox wider than long, and 2.0-2.8X wider
(catalog); Spencer 1969: 26 (geography). than eye width (when viewed from dorsal
221 (key), 276 (diagnosis, distribution, il- aspect); with 4 fronto-orbital setae, poste-
lustration of basiphallus); Spencer 1981: rior 2 reclinate and subequal, anterior 2
365 (key), 425 (redescription, distribu- convergent and subequal or with anterior-
tion, illustration of basiphallus, comment most one smaller; with row of small pro-
on relationship with Phytomyzxi lupini clinate setulae between fronto-orbital setae
Sehgal); Spencer and Steyskal 1986: 186 and orbital margin, anteriorly becoming
(key, diagnosis, distribution, illustration slightly larger and convergent. Lunule
mm
of basiphallus, comment on relationship 0.09-0.12 high. Gena high, 0.6-0.7
with Phytomyza eumorpha Frey). higher than eye height. Eye 1.1-1.2X high-
— er than wide (when viewed from lateral as-
Diagnosis. Face and frons mostly yel- pect). One strong oral vibrissa, with several
low; gena high; face and gena strongly re- smaller setulae along oral margin. Face and
ceding in lateral view; epistoma absent; 4 gena distinctly receding in lateral view.
fronto-orbital setae, posterior 2 reclinate, Thorax: Notum and scutellum entirely sil-
anterior 2 convergent. Notum and scutellum very-grey pruinose. Chaetotaxy: 1+3 dor-
silver pruinose; dorsocentral setae 1+3; sin- socentral setae (occasionally with fine su-
gle row (2-6 pairs) of acrostichal setulae; pernumerary setae), with cluster of setulae
forecoxa yellow; pleuron silvery-grey pru- just anterior to anteriormost seta; single row
inose, except yellow only along dorsal and (2-6 pairs) of acrostichal setulae; presu-
1
posterior borders of anepisternum, dorsal
tural intra-alar seta; postsutural intra-alar
1
edge of meron, and surrounding posterior seta; 1 postalar seta; 1 postpronotal seta
spiracle; femora dark silver pruinose, yel- (with several supernumerary setulae); 2 no-
low apically; tibiae and tarsi dark. Abdom- topleural setae; 2 pairs scutellar setae; oth-
inal tergites and sternites brown, with yel- erwise bare, with few supernumerary setu-
low posterior edges. In male, paramere bi- lae. Pleuron silvery-grey pruinose. except
lobed distally, with inner lobe straight, and yellow along dorsal and posterior borders
outer lobe curving and overlapping with in- of anepisternum, dorsal edge of meron, and
ner; basiphallus gently S-curved in lateral surrounding posterior spiracle. Chaetotaxy:
view with edges along middle of curve wid- proepisternal seta; 3-4 anepisternal setae
1
ened slightly, strongly bilobed distally in along posterior edge, middle 1-2 strong,
ventral aspect; apex of distiphallus a single, outer ones fine, occasionally with 1—2 fine
large, membrane-bounded opening with setae in dorsal part, anterior of this edge; 2
sclerotization giving appearance of being katepisternal setae, posterior one stronger.
bilobed. In female, oviscape 1.3-1.6X lon- Legs: Forecoxa yellow, getting darker in
ger than basal width, shining brown, with dorsal Vs; mid- and hindcoxae dark. Femora
ring of long set—ae distally. silvery-grey pruinose, yellow distally. Tib-
Adults, 6, 9. Body length 2.3-2.8 mm. iae and tarsi dark brown. Wing: Length
Head: Mostly yellow, except ocellar region 2.4—2.8 mm. Distance between end of R,
and behind head (median occipital sclerite, and R2+3 1.4-1.9X longer than that between
occiput, and postgena) silvery-grey prui- R4,<, and M|,2- Halter yellow. Abdomen:
nose, clypeus and palpus light brown, pre- Tergites and sternites brown pruinose, but
mentum and lateral part of antennal scape yellow along posterior edges. Male genita-
504 i'RC)('r;i:i:)iNc;s oi'imf-: nNTOMOixx'.icAi, sociirrY ()!• Washington
lid (F'igs. 1-4): RparKlriiiin rounded, with miiiidfd, VII-1998, Fynn AdIer (I (5,3 9,
small setae in addition to eovering of small (\S('A; I r^ I —9, USNM).
hairs; surstyliis fused to epandrium. with Distribution. C^anada (Alberta, British
densely clustered hairs, many directed me- C'olinnbia); United States (California, Col-
dially (Pig. I). Cerci small. Hypandrium U- orado, Washington, Wisconsin, Wyoming).
shaped from dorsal view, with medially di- The single paraleclotype from Wisconsin is
rected process near middle, and with bi- unambiguously labelled (Polk Co. Wis.,
lobcd process dislally on each posterior arm .luly. Maker), although the presence of this
(Fig. 2). Paramere (poslgonite ol other au- species in northwestern Wisconsin (where
thors) bilobed dislally, with inner lobe the elevation is below 500 m), seems un-
straight, and outer lobe curving and over- likely, as all other known specimens are
lapping with inner (h'ig. 2). Kjaculatory from the Kocky Mountains and the Sierra
ajiodeme 2.OX longer than high, with tlistal Nevada, at elevations above 2,()()() m. Spen-
edge Ian-like (Fig. 3). Aedeagus with bas- cer ( 1969) even comments that this species
iphallus gently S-curved in lateral view, is likely to be limited to this high elevation
with edges along middle ol curve widened western /one, despite the record in Wiscon-
slightly (I'ig. 2); basi|')hallus in ventral as- sin, which he also consider—ed dubious.
Behavioral observations. Adult F. suh-
pect strongly bilobed dislally (big. 4). Dis-
tciH'lld were observed on leaves and bracts
tiphallus scleroti/.ed in three parts: central
of C. niiniald in late .luly 1998 at FJneraltl
speiin duel (Fig. 2), paired, elongated, an-
Fake, Colorado, where most were in llower.
leriorly-direeled sclerites, and paired pos-
Pairs of adults, or occasionally three adults,
teriorly-directed ajiical sclerites (big. 4);
were observetl in what appeared to be mat-
elongated sclerites conlluent with apical
ing positions.
sclerites through membrane; apex ol disti-
Approximately two weeks later, adult
phallus a single, large, membrane-bounded
Hies were no longer observed, but lly larvae
opening, des|"»ile appearance ol being truly
were common inside the locules of matur-
bilobed. I'ciiuilc icnniiKilid: Oviscape
ing fruits. Up to three larvae were found
0.36-0.46 unn wide at base, length 1.3-
per single fruit. Because there was no ob-
I.6X greater than basal width; shining
vious damage to these fruits (i.e., no evi-
brown, with ring of long hairs dislally; with
dence ()f larval entry holes), it seems likely
light covering of silver-grey pruinosity in that ovipositilion was directly into fruits.
basal '/. Farvae consumed seeds while leaving be-
Type material. LT9 (USNM), Ml.
hind the netlike outer seed coat, causing ex-
Kainier, Wash] ingtonj., above Fongmire's, tensive damage (AdIer 2002).
5,000 It., Aug. 3, I \')\i)5 Idate handwritten!/ By early September, C. niiiiidid fruits had
Type No. .^0021 U.S.N.M |red; number matured anil begun tiehiscing, and the Hies
handwritten |/l'hytomy/a subtenella F'rt)st had pupaiiated. These puparia were fe)und
I handwritten; black submargin—|. both inside and outside fruits, hi the latter
Other material examined. UvSA: Wis- case, exit holes were evident in the capsule
consin, Folk Co., .July, Raker (IFFT9, wall and at times puparia were found pro-
USNM); C^ililbrnia, b:i Dorado C\)., bxho truding through these holes. The duration of
Fake 12,250 m el.|, b:.l. Schlinger, 23-VIF the puparial stage in the field is not known;
F)5.S (I ci, I V, USNM); C\>lorado, (Jun- lield collected puparia emerged after sev-
m
nison Co., I^merald Fake, 3,150 el., eral months in the laboratory.
39"()()'41"N l()7"()2'32"W, reared Irom (V/.v-
Discussion
lilU'Jd tiiinidtd. 5.X1.IW6 (emer. lll-IW?),
Fynn Adier (I c^, 2 9, CSCA; I c^, I 9, The grtnip of riiyiomyzd presented in Ta-
USNM), hand collected from Cdslillcja ble all attack Orobanchaceae, parasitic
I
VOLUME NUMBER
106, 3 505
Tabic I. Plivloiiiyzci species known to Iced on jilants in ihc laniily Orobanchaccac, arranged by hosl genus;
* = new record; ' = probable feeding silc. All hosl gcneia are in the heniipaiasiiic tribe Rhinantheae, except
for Orohiinchc which is in the holoparasitic tribe Orobanchcac.
S|K-CICS
PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
506
orobanchia, P. eumorpha and P. orinden- LSA, who thanks Judah Dinnel for help
sis, and in fact, the genitalia of P. eumorpha with field work. This work was funded by
appear most similar to P. siibtenella. National Science Foundation Dissertation
Castilleja species, and other Orobancha- Improvement Grant DEB98-00885 to LSA.
ceae, are known to parasitize species of Lii- We also thank Wayne N. Mathis (USNM)
pinus and obtain alkaloids, secondary com- for providing access to and help with the
pounds implicated in resistance to herbi- lectotype of Phytomyzci siibtenella, Eric
vores, as well as nitrogen resources from Fisher (CSCA) for reviewing the manu-
this association (Stermitz and Harris 1987, script, and Fred Hrusa (California Depart-
&
Stermitz et al. 1989, Arslanian et al. 1990, ment of Food Agriculture) for help with
Boros et al. 1991, Stermitz and Pomeroy understanding botanical issues surrounding
1992). Because of the putatitive close re- the circumscription of Orobanchaceae.
lationships among some of these taxa, one
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