A new cryptic species of Trichogramma (hymenoptera: Trichogrammatidae) from the Mojave Desert of California as determined by morphological, reproductive and molecular data

10 Pages·1997·4.4 MB·

by  J D Pinto

PROC. ENTOMOL. SOC. WASH.
99(2), 1997, pp. 238-247
A NEW CRYPTIC SPECIES OF TRICHOGRAMMA
(HYMENOPTERA: TRICHOGRAMMATIDAE) FROM THE
MOJAVE DESERT OF CALIFORNIA
AS DETERMINED BY MORPHOLOGICAL,
REPRODUCTIVE AND MOLECULAR DATA
John D. Pinto, Richard Stouthamer, and Gary R. Platner
(JDP, GRP) Department ofEntomology, University ofCalifornia, Riverside, CA 92521,
U.S.A.; (RS) Department of Entomology, Wageningen Agricultural University, 6700 EH
Wageningen, The Netherlands.
—
Abstract. A new species of Trichogramma, T. kaykai, is described from the deserts
of southern California where it is a common egg parasitoid of the lycaenid butterfly
Apodemia mormo. The new species is closely related to T. deion, the most common
Trichogramma in western North America. It is distinguished from T. deion by morpho-
logical, allozymic and ITS2 sequence differences; the two also appearto bereproductively
incompatible.
Key Words: Trichogramma, new species, allozymes, ITS2 DNA sequences
Collections of parasitized eggs of the ly- description below is followed by a brief
caenid butterfly Apodemia mormo (C. and summary of crossing results, and allozymic
R. Felder) on Eriogonum inflatum in the and DNA sequence comparisons. The mo-
Mojave Desert in the spring of 1988 were lecular data are compared among the new
commonly parasitized by a species of species, T. deion, T. pretiosum Riley and
Trichogramma. This species was originally the Interior form of T. platneri Nagarkatti.
considered as a light color form of T. deion All taxa are similar morphologically and
Pinto and Oatman, the most conunon Trich- occur in sympatry in the Mojave Desert.
ogramma in western North America (Pinto
et al. 1986). This conclusion was ques- Species Description
tioned when typical T. deion was found at The description is based on an exami-
the same localities also parasitizingA. mor- nation of material from all localities com-
mo eggs. Subsequent study showed thatthis prising the range of the new species. The
form differed from T. deion by minor but majority of this material consists of wasps
consistent morphological traits, and by mo- individually mounted on glass slides in
lecular differences (allozymes and ITS2 se- Canada balsam. For body length and color
quences). In addition, strains of the two several specimens of both sexes [reared at
proved to be reproductively incompatible in ca. 24° C. and on eggs of Trichoplusia ni
the laboratory. Because this new species (Hiibner)], and originating from two local-
continues to be the subject of various eco- ities, were critically point dried after being
logical and cytological studies (e.g. Stou- killed in ethanol and mounted on cards. The
thamer and Kazmer 1994) it is important material of T. deion compared in the diag-
that it receive a formal name. The species nosis was reared under similar conditions.
I
VOLUME NUMBER
99, 2 239
Fig. 1. Antenna of Trichogramma kaykai male (ventral ofleft antenna) showing base offlagellum (1500X).
Arrows point to positions 1-3 (from right to left) showing presence ofa single basiconic peg sensillaatpositions
1 and 3 only. In T. deion, all three positions have a single sensilla.
mm
Unless indicated, quantitative data (means Body length 0.4-0.5 in males, 0.5-
± SD and ranges) are taken from five ran- 0.6 mm in females.
domly selected males, all from different lo- Forewing 0.28 ± 0.02 mm wide, 0.54 ±
calities. The hind tibial length of these 0.01 as wide as long, setation moderately
specimens ranged from 0.16-0.19 mm. The dense with 20-29 setae between 4th and
terminology used in the description follows 5th setal tracks, longest fringe setae 0.14-
Pinto (1992). 0.20 maximum forewing width. Hind wing
with 3-4 and 6-8 setae in anterior and pos-
Trichogramma kaykai Pinto and
Stouthamer, new species terior tracks, respectively, the latter attain-
ing 0.5-0.6 the distance from hamuli to
Trichogramma sp. near deion: Stouthamer apex of wing. Scutellum with anterior pair
and Kazmer, 1994:317. of setae short, fine, ca. 0.2 the length of
Trichogramma sp.: Pinto and Stouthamer, posterior—pair.
1994:23 (Table 1.1). Male. Antenna with flagellum 0.17 ±
Color sexually dimorphic. Male darker 0.01 mm in length, slightly curved, 6.03 ±
with mesosoma including coxae orange 0.24 as long as wide, 1.00 ± 0.04 as long
brown to yellow brown; pronotum and me- as hind tibia, 2.1 ± 0.05 as long as scape;
soscutum typically darkest; metasoma pri- flagellar setae elongate, gradually tapering
marily light brown; propodeum and poste- to apex, the longest of these setae 3.18 ±
rior part of scutellum typically lightest, yel- 0.21 (3.0-3.5) the basal width offlagellum;
low orange in color. Female considerably basiconic peg sensilla (BPS) relatively
lighter than male. Most of meso- and me- small, only slightly expanded apically, for-
tasoma uniformly yellow orange; only pro- mula 1-0(1)-1-0-1-1 (i.e. position 2 usually
notum, pro- and mesocoxa and ovipositor lacking a sensilla as in Fig. 1, also see be-
suffused with brown; anterior 2-3 metaso- low for explanation); flagellum lacking un-
mal terga lightly suffused with brown in socketed setae.
some specimens. Genital capsule (GC) (Figs. 2, 3) mod-
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240 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
erately broad, 0.34 ± 0.02 as wide as long; dian National Collection, Ottawa; Univer-
sides broadly constricted at level of inter- sity of California, Riverside; University of
volsellar process (IVP); parameres relative- California, Berkeley; and The Natural His-
ly straight, moderately and evenly conver- tory Museum, London. All type specimens
gent to apex; apical distance (between apex are F1-F7 generation individuals from a
of parameres and base of IVP) 0.29 ± 0.01 culture started with a single female.
—
total GC length; apical width (at base of Etymology. The specific name is an ar-
IVP) 0.63 ± 0.2 greatest width of GC; dor- bitrary combination of letters, treated as a
sal aperature (DA) relatively elongate, nar- noun in the nominative singular and faithful
rowing considerably posteriorly, its length to "KK," the informal epithet applied to
0.63 ± 0.03 that of GC; dorsal lamina this species in our laboratory for several
(DLA) arising slightly anterior to middle of years.
GC, moderately notched at base and nar- Diagnosis. Trichogramma kaykai is
rowing directly posterior to notch forming morphologically most similar to T. deion
shoulders which usually do not approach and T. pretiosum. All three have similar
sides of GC; posterior extension of DLA genitalic structure and relatively elongate
relatively elongate, linguiform, its width at setae on the male antenna. Males of T. kay-
level of IVP subequal to aedeagus width; kai and T. deion are separated from T. pre-
DLA length from apex of DA = 0.79 ± tiosum by the more distinctly sclerotized
0.10 the apical distance and occupying 0.5- posterior extension ofthe dorsal lamina and
0.6 of this distance, usually extending the BPS formula on the antenna. Unlike T.
slightly beyond apex of volsellae (VS); VS kaykai and T. deion, T. pretiosum has a pair
slightly bowed, occupying 0.4-0.5 the api- of BPS at the second and third positions.
cal distance; IVP narrowly triangular, mod- Differences in this trait and male genitalia
erately elongate, occupying 0.3-0.4 the api- in T. deion and T. pretiosum are summa-
cal distance, its apex usually slightly ante- rized in Pinto et al. (1986).
rior to that of VS; ventral processes posi- Trichogramma kaykai is separated from
tioned at base of IVP, slightly protuberant; T. deion by color, minor but consistent dif-
ventral ridge relatively short and indistinct, ferences in the male genitalia, BPS formula,
occupying ca. 0.3 the distance from the and ovipositor length. Color in T. deion is
base of the IVP to the base of GC. Aede- not obviously sexually dimorphic as it is in
agus length subequal to that ofGC and 0.70 T. kaykai. In T. deion the mesoscutum and
± 0.03 that ofthe hind tibia; apodemes con- metasoma of both sexes are typically
sisting of c—a. 0.5 entire aedeagus length. brownish. Males ofT. kaykai are similarbut
Female. Antenna with funicle segments usually a lighter brown; females, however,
subquadrate; usually with 1 BPS on the first are almost uniformly yellow or yellow or-
funicular segment; second funicular seg- ange and are easily separated from T. deion
ment usually lacking BPS. Ovipositor sub- on this basis.
equal in l—ength to hind tibia (see below). In most Trichogramma there are one or
Types. Holotype 6 and allotype 9 two basiconic peg sensilla (BPS) at each of
from CALIFORNIA, San Bernardino Co., the first three positions of the male flagel-
Sheephole Pass, 3 mi. N. on Amboy Rd.; lum. The presence of these sensilla are rel-
ex. Apodemia mormo on Eriogonum infla- atively stable within species, although they
tum Torr. & Frem.; iv-30-93; K. Cooper, J. may be reduced or completely absent at
&
Pinto G. Platner, collrs.; in the National these positions in abnormally small individ-
Museum of Natural History, Smithsonian uals. T. deion almost always has a single
Institution, Washington, D. C. Eight 6 and BPS at the first three positions. In T. kaykai
3 9 paratypes with same data as primary a single sensilla is present at positions 1 and
type deposited in collections of the Cana- 3 but usually not at position 2 (Fig. 1). This
VOLUME 99, NUMBER 2 241
DLA
DA
Figs. 2-4. Genital capsule of male (posterior end above). 2, Trichogramma kaykai (dorsal view), DLA =
dorsal lamina, DA = dorsal aperature, VS = volsella. 3, T. kaykai (ventral view). 4, T. deion (dorsal view).
Note in T. kaykai the DA is narrower apically, and the DLA is narrower at its base (immediately posterior to
notch) and extends beyond the apex ofthe VS.
feature is variable, however. Whereas the notch, and, most importantly, the dorsal
formula in T. deion is relatively stable, aperature is somewhat longer and narrows
about 35% of 135 non-sib males of T. kay- considerably at its posterior end. Correlated
kai examined had a sensilla at this position. with this difference, the length ofthe dorsal
Females of T. kaykai can also usually be lamina, measured from the posterior border
separated from T. deion by the absence of of the dorsal aperature to its apex, is less in
a BPS at the equivalent antennal position, T. kaykai and averages 0.79 the apical dis-
i.e., the apex of the second funicular seg- tance; in T. deion this ratio averages 0.93
ment. the apical distance. Also, in T. kaykai the
Most males of T. kaykai can be separated lamina typically extends to a level slightly
from T. deion by genitalia structure {cf. posterior to the apex ofthe volsellae; it usu-
Figs. 2, 4). In T. kaykai the genital capsule ally does not extend that far in T. deion.
is narrower apically, the dorsal lamina is Females of T. kaykai are most easily dis-
narrower immediately posterior to its basal tinguished by color. However, the longer
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242 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
ovipositor also helps distinguish it from T. J. Pinto, R. Stouthamer. San Bernardino
deion. Samples of 10 females of each spe- Co. Barstow, ca. 10 mi. NE., and ca. 8 mi.
cies from localities where the two were E.; v-29-96, v-15-96; L. Bolijn, B. Deijkers.
sympatric were compared. All originated Beacon Station; vi-6-96; L. Bolijn, B.
from different host eggs and had a hind tib- Deijkers. Danby; iv-11-88, iv-30-88, iv-27-
ial length ranging from 0.19-0.21 mm. In 95; G. Pratt/D. Kazmer/R. Stouthamer.
T. kaykai, the ratio ofovipositor to hind tib- Joshua Tree; vi-15-96; L. Bolijn, B. Deijk-
ial length was 1.00 ± 0.03; in T. deion this ers. Hwy. 66 between Bagdad and Siberia;
ratio was 0.93 ± 0.04. Although the range iv-27-95; R. Stouthamer. Interstate 15, be-
of variation does overlap, this feature used tween Victorville and Barstow; v-29-96; L.
with the significantly lighter coloration and Bolijn, B. Deijkers. Kramer Hills; v-14-88,
absence of a BCP on the second funicular iv-24-95; D. Kazmer, R. Stouthamer/J. Ben-
segment should provide straightforward nett, R. Stouthamer. Lucerne Valley, ca. 12
separation of females. mi. N.; v-29-96; L. Bolijn, B. Deijkers.
Geographic distribution. Trichogram- Sheephole Pass area; v-14-88, iv-27-95; D.
ma kaykai has only been collected in south- Kazmer, R. Stouthamer. Sheephole Pass, 3
em California -in the Mojave Desert and at mi. N. (on Amboy Rd.) (type locality);
the north—ern limits of the Sonoran Desert. iv-30-93; K. Cooper, J. Pinto, G. Platner.
Hosts. The primary host of this species Yucca Valley; vi-1-96; L. Bolijn, B. Deijk-
is the egg of Apodemia mormo (Lycaeni- ers. —
dae) laid on Eriogonum inflatum. This ly- Notes. Both thelytokous and arrheno-
caenid has been divided into several sub- tokous populations of T. kaykai have been
species (Miller and Brown 1981). All re- collected. As in many species of Tricho-
cords of T. kaykai are from A. m. deserti gramma, thelytoky in this species is caused
Barnes and McDunnough. Trichogramma by Wolbachia infection and can be cured
kaykai also has been taken a single time with antibiotic treatment (Stouthamer et al.
(Pinyon Mt., Kern Co.) on the egg of an- 1990). Populations with both modes of re-
other lycaenid, Icaricia lupini (Boisduval), production occur together in the Mojave
on Eriogonumfascicu—latum Bentham. Desert. The few collections from the So-
Material examined. 401 specimens of noran Desert are all thelytokous.
both sexes. The material examined includes Unlike T. deion which has very broad
specimens emerging from field collected host and geographic ranges in western
host eggs and from cultures initiated with North America (Pinto et al. 1986), T. kaykai
these parent—als. has been retrieved almost totally from eggs
Records. Except for the single record ofApodemia mormo in the deserts ofsouth-
from Pinyon Mt. (see Hosts), all following em California. Both species are known to
collections originatedfromthe eggs ofApo- occur together on Apodemia at several lo-
demia mormo on Eriogonum inflatum. calities, although T. kaykai is more com-
UNITED STATES. California. Kern Co. mon and appears to be the dominant egg
El Paso Mts. (Bickel Camp); vii-29-96; R. parasite ofthis butterfly in the Mojave Des-
Stouthamer. Pinyon Mt.; vi-4-87; G. Pratt. ert. Of a sample of 256 parasitized A. mor-
Walker Pass, 2 mi. E.; iv-19-89; G. Pratt. mo eggs collected at several sites of sym-
Last Chance Cyn.; v-14-88; D. Kazmer, R. patry during the spring of 1995, 212 or
Stouthamer; also numerous collections by 82.9% were attacked by T. kaykai; only 38
several collectors from iv-vi-95/96. Rands- or 14.8% were parasitized by T. deion. The
burg; V-14-88; D. Kazmer, R. Stouthamer. remainder (2.3%) were attacked by a third
Riverside Co. Dillon Rd., several collec- and undescribed species. In a few cases, T.
tions between immediately east of Indio deion and T. kaykai emerged from the same
and Fun Valley (all thelytokous); iv-26-95; egg.
VOLUME NUMBER
99, 2 243
The eggs ofA. mormo are relativelylarge phoglucomutase (2.7.5.1), Pgm. These loci,
and several Trichogramma typically among others, were also compared between
emerge from a single egg. In a sample of T. pretiosum and T. deion in our earlier
33 eggs collected in 1988 from several lo- study.
calities the average number of T. kaykai The four T. kaykai cultures examined
emerging from each was 4.6 ±1.2 (range were from Walker Pass (KWPA), Last
= 1-7). Most of the progeny were female; Chance Cyn. (KLC187), and between Bag-
most parasitized eggs result in a single male dad and Siberia (KRB85), three Mojave
and 3-4 females. The average number of Desert localities, and Dillon Rd. (N. of In-
males emerging from this sample (exclud- dio) (KAW73), a Sonoran Desert site. The
ing eggs resulting in thelytokous wasps) cultures of T. deion examined represent
was 1.19 ± 0.75 (range = 0-3, n = 31). much ofthe range of the species in western
Collections of other species of host at North America. The origin of the compar-
sites where T. kaykai occurs are minimal. —ison cultures were as follows: T. pretiosum
The only such collection was made on 14 /Riverside, CA (PRV4) and Wyndham,
May 1988 at Last Chance Canyon in Kern Aust—ralia (PAWD). Interior form of T. pla—t-
NV
County. The eight parasitized eggs of A. neri Mesquite, (IMSQ). T. deion
mormo collected on Eriogonum inflatum Riverside, CA (DRV4); Seven Pines, CA
were attacked by both T. deion (5) and T. (DSVP); Covelo, CA (DCLO); Portal, AZ
NM
kaykai (3). However, only T. deion emerged (DPTL); Granite Gap (Hidalgo Co.),
MT
from 23 parasitized eggs of an undeter- (DGGP); Miles City, (DMCT); Paul's
mined Pieridae collected from a species of Place (Kern Co.), CA (DPPL); and Last
Stanleya (Brassicaceae). Chance Cyn (DLCl). All but two of these
comparison cultures (DPPL and DLCl)
Molecular Data also were examined in our previous paper
AUozymes (Pinto et al. 1993). The culture IMSQ was
originally assigned to the interior form of
An earlier paper compared allozymes in T. platneri (Pinto et al. 1992). This form
T. pretiosum and T. deion (Pinto et al. represents a new species and will be de-
1993) and reported consistent allelic differ- scribed in the near future. Until then we
ences between these close relatives. Forthis continue to refer to it as before.
study we examined ten loci in four cultures All cultures compared represented iso-
of T. kaykai, and compared them with one female lines. One culture of T. kaykai
culture of the interior form of T. platneh (KAW73) was originally thelytokous; all
Nagarkatti, two cultures of T. pretiosum others were arrhenotokous. In the latter
and seven of T. deion. All exemplars were case, the female used to initiate a culture
run concurrently. The cultures chosen ofthe had mated with a brother.
latter three species represented most of the Electrophoretic analysis followed meth-
known allelic diversity in Trichogramma at ods in our earlier studies (Pinto et al. 1992,
the loci examined. The enzyme systems 1993) and were originally detailed by Kaz-
used are as follows: Aconitase (4.2.1.3), mer (1991). Briefly, two females perculture
Aeon; acid phosphatase (3.1.3.2), Acp-II; were individually analyzed at each locus by
fumarase (4.2.1.2), Fum; a-glycerolphos- isoelectric focusing in one to two layers of
phate dehydrogenase (1.1.1.8), aGpd-IT, cellulose acetate membranes using a single
glucose-phosphate isomerase (5.3.1.9), Gpi; blend of carrier ampholytes (8% pH 4-6.5
glucose-6-phosphate dehydrogenase (1.1.1.49), and 2% pH 3-10 pharmalytes) (Sigma
G6pd; isocitrate dehydrogenase (1.1.1.42), Chemical, St. Louis, MO) and an effective
Idh; malate dehydrogenase (1.1.1.37), Mdh- gel length of 4.5 cm. Each culture repre-
ir, malic enzyme (1.1.1.40), Me; and phos- sented an isofemale line initiated from a
244 PROCEEDINGS OF THE ENTOMOLOGICAL SOCIETY OF WASHINGTON
Table L Allelic comparison of Trichogramma kaykai with closely related species at eight loci.^''
VOLUME NUMBER
99, 2 245
Table 2. The size of the ITS2 gene and size of the restriction fragments generated by restriction enzymes
MSEl and ECORl.
246 PROCEEDINGS OFTHE ENTOMOLOGICAL SOCIETY OF WASHINGTON
terns using a Prism Ready Reaction 1994). In this study, four cultures ofT. kay-
DyeDeoxyo Terminator Cycle sequence kai were crossed (at 25°C) with a culture of
kit). The size of digestion products of the T. deion from Dillon Rd., near Indio, CA
ITS2 gene using different restriction en- (DAW6) and among themselves. The T.
zymes was determined. Characteristic dif- kaykai cultures used included two from
ferences among the species were found us- Danby, CA (KDA22, KDA23), and two
ing ECORl—and MSEl. from Last Chance Cyn., CA (KLCl8,
Resuhs. The sequences of the ITS2 KLC21). Crossing procedures employed
genes have been deposited in the EMBL, closely followed those detailed in Pinto et
GenBank and DDEJ Nucleotide Sequence al. (1991). All crosses are based on individ-
Databases. Accession numbers for the spe- ual pairings. All combinations of hetero-
cies and cultures indicated in Table 2 are as gamic crosses were performed concurrently
follows: T. deion—lJ76223 (DCLO), with homogamic controls, resulting in a to-
U76224 (DLCl), U76225 (DSVP); T. pre- tal of 20 crosses. All crosses included 20
tiosum—Ul6226 (PRV4), U76227 (PIRV); replicates in each direction. For determin-
T. kaykai—U7622S (KSHl), U7622—9 ing relative compatibility between cultures
(KLCl); Interior form of T. platneri the mean sex ratio (MSR) was calculated as
U76230 (IMSQ). the percentage of female progeny. The rel-
The size of the T. kaykai ITS2 gene is ative compatibility of an interculture cross
consistently larger than that of either T. (A X B) is expressed as two percentages:
deion and T. pretiosum. The size of the 100% X MSR (A female X B male)/MSR
ITS2 gene in order from large to small is: (A female X A male); and the same based
Interior form of T. platneri > T. kaykai > on the reci—procal.
(T. deion, T. pretiosum). The consistent and Results. The crosses between cultures
characteristic differences found in the ITS2 of T. kaykai and T. deion were completely
sequences in these four species arereflected incompatible. Female production is the ev-
in differences in restriction length frag- idence for reproductive compatibility in ar-
ments when the ITS2 gene is restrictedwith rhenotokous Hymenoptera and not a single
the enzymes MSEl and ECORl as shown female was produced in any of the four
in Table 2. The interior form of T. platneri heterospecific trials. The mean relative
differs from the other species in the size of compatibility among the 12 homospecific
its ITS2 gene (515 bp) and in the presence crosses of T. kaykai cultures was 78.0 and
of the restriction site for ECORl. Tricho- ranged from 49.0 to 97.5. The least com-
gramma kaykai differs from both T. deion patible cross (49.0) was between KDA22
and T. pretiosum in the size of its ITS2 females and KLC21 males. The reciprocal
gene (470 bp vs 400-410 bp). Also, the cross was considerably stronger (83.1).
ITS2 gene of T. kaykai is cut in two large There was no evidence that the sympatric
fragments by MSEl (270 and 200 bp) cultures (mean compatibility = 74.2, n =
whereas T. deion is cut into three fragments 4) were more compatible than the allopa-
with the largest ca. 300 bp; T. pretiosum is triates (mean compatibility = 79.8, n = 8).
not restricted by this enzyme. As with al- In fact, the highest levels (92.6, 97.5) were
lozymes, the differences between T. deion among allopatric cultures.
and T. kaykai occur in both allopatric and
Concluding Remarks
sympatric collections.
Morphologically similar species of
Reproductive Data
Trichogramma as exemplified by T. kaykai
Reproductive compatibility has frequent- and T. deion are apparently quite common
ly been used to support species hypotheses (Pinto and Stouthamer 1994). Yet, we feel
in Trichogramma (Pinto and Stouthamer that in this genus such cryptic species
VOLUME NUMBER
99. 2 247
should be described only after putative checklist of the butterflies of America north of
morphological differences are shown to be Mexico. The Lepidopterists' Society MemoirNo.
geographically stable and, ideally, found to 2, 280 pp.
Pinto, J. D. 1992. Novel taxa ofTrichogramma from
correlate with other character sources. This the New World tropics and Australia (Hymenop-
requires extensive collecting of all forms tera: Trichogrammatidae). Journal of the New
involved and an attempt to delineate at least York Entomological Society 100:621-633.
rough geographic distributions. One goal of Pinto, J. D. and R. Stouthamer. 1994. Systematics of
such work should be the identification of the Trichogrammatidae with emphasis on Tricho-
gramma, Chapter 1, pp. 1-36. In Wajnberg,E.and
areas of sympatry since it is at such local- S. A. Hassan, eds.. Biological control with egg
ities that the stability of character differ- parasitoids. CAB International, Wallingford.
ences can be most rigorously tested for. In Pinto, J. D., E. R. Oatman and G. R. Platner. 1986.
the case of T. kaykai, we have shown that Trichogramma pretiosum and a new cryptic spe-
this species has only minor morphological cies occurring sympatrically in southwestern
North America (Hymenoptera: Trichogrammati-
differences from T. deion but that these are dae). Annals of the Entomological Society of
consistent at several localities including America 79:1019-1028.
those where the two occur together. Differ- Pinto, J. D., R. Stouthamer, G. R. Platner and E. R.
ences in allozymes and the ITS2 sequence, Oatman. 1991. Variation in reproductivecompat-
as well as crossing incompatibility, give ibility in Trichogramma and its taxonomic signif-
icance (Hymenoptera: Trichogrammatidae). An-
greater confidence that species recognition nals ofthe Entomological Society ofAmerica 84:
is warranted. Thus far we have no evidence 37-46.
of gene flow between these two species. Pinto. J. D., D. J. Kazmer, G. R. Platner and C. A.
However, a focus of future work should in- Sassaman. 1992. Taxonomy of the Trichogram-
maminutumcomplex (Hymenoptera:Trichogram-
clude additional crossing and molecular
matidae): allozymic variation and its relationship
studies in zones of sympatry. Our efforts in toreproductiveandgeographicdata. Annalsofthe
both areas are preliminary. Entomological Society ofAmerica 85:413-422.
Pinto, J. D., G. R. Platner and C. A. Sassaman. 1993.
Acknowledgments Electrophoretic study of two closely related spe-
We thank Gordon Pratt, University of cies of North American Trichogramma: T. pre-
tiosum and T. deion (Hymenoptera: Trichogram-
California, Riverside, for his contribution to matidae). Annals ofthe Entomological Society of
this study. He was the first to collect the America 86:702-709.
new species and also provided valuable in- Stouthamer, R., R. E Luckand W. D. Hamilton. 1990.
formation on its host, A. mormo. We also Antibiotics cause parthenogenetic Trichogramma
thank F. J. P. M. van Kan for determining etomryevoefrtStcoiesnecxe.sP,rUocSeAedi8n7g:s24o2f4t-h2e4N2a7t.ionalAcad-
the ITS2 sequences reported in this study, Stouthamer, R., and D. J. Kazmer 1994. Cytogenetics
and L. Bolijn and B. Deijkers for several of of microbe-associated parthenogenesis and its
the collections made in the Mojave Desert consequences for gene flow in Trichogramma
in the spring of 1996. wasps. Heredity 73:317-327.
Swofford, D. L. and R. B. Selander 1989. BIOSYS-I.
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