Parasitoids of Leptoglossus occidentalis Heidemann (Heteroptera: Coreidae) in British Columbia

2004·1.2 MB·English

by  Sarah L Bates

J.Entomol. Soc. Brit. Columbia 101,Dhchmber2004 143
SCIENTIFIC NOTE
Parasitoids ofLeptoglossus occidentalis Heidemann
(Heteroptera: Coreidae) in British Columbia
SARAH L. BATES* ^ and JOHN H. BORDEN* ^
—
ABSTRACT Eggs ofthe western conifer seed bug, Leptoglossus occidentalis Heide-
mann, were parasitized in the field in British Columbia, Canada, by Giyonpennsylvani-
cum (Ashmead),AnastatuspearsalliAshmeadandanunidentified Ooencyrtus spp. Ash-
mead. Leptoglossus occidentalis represents a new host record for all three parasitoids.
Gryonpennsylvanicum has notpreviouslybeen reportedin Canada.
The western conifer seed bug, Lep- mented host,L. occidentalis.
toglossus occidentalis Heidemann, feeds Leptoglossus occidentalis eggs were
on several species ofconifers (Hedlin etal. obtained by caging adult females on cone-
1981), and can cause substantial yield bearing branches of lodgepole pine, Pinus
losses in high-value seed orchards (Bates contorta var. latifolia Engelmann, at
et al, 2002; Strong et al. 2001). The gen- Kalamalka Seed Orchard, Vernon, B.C.
eralist egg parasitoid,Anastatus bifasciatus (50.27 "N, 119.28 °W). In 2001, females
(Geoffroy) (Hymenoptera: Eupelmidae), were collected from orchard trees, and in
has recently been recovered from L. occi- 2002 they were obtained from an outdoor
dentalis egg masses in Italy (Camponogara colony ofoverwintered insects maintained
et al. 2003) but little else is known about at Simon Eraser University. Eggs were
eggparasitoids ofL. occidentalis laid in a single row along needles, and
Members ofthe family Scelionidae are were collected by removing the entire nee-
egg parasitoids of several economically- dle. Ten egg masses, each bearing 10-13
important hemipteran pests (Masner 1983). eggs, were transferred to separate trees
Gryon pennsylvanicum (Ashmead) is a throughout the orchard on 5 July in 2001.
polyphagous, solitary parasitoid ofcoreids, In 2002, 24 egg masses were set out on
including Anasa tristis (De Geer) and sev- trees on 30 June. Wire paper clips were
eral Leptoglossus species other than occi- used to fasten egg-bearing needles to foli-
dentalis (Masner 1983; Mitchell 1983; age. Eggs were 0-7 d old at the time of
Yasuda 1990; Daane et al. 2001). Anas- transfer. After three weeks, all unhatched
tatus pearsalli Ashmead (Hymenoptera: eggs were transferred to Petri dishes, main-
Eupelmidae) is widely distributed through- tained at room temperature in the labora-
out the nearctic, and parasitizes hosts from tory and monitored for parasitoid emer-
several orders and families including gence. Voucherparasitoid specimens were
Coreidae (Burks 1979). Members of the deposited in Canadian National Collection
genus Ooencyrtus (Hymenoptera: Encyrti- ofInsects, Agriculture and Agri-Food Can-
dae) are also common egg parasitoids ofa ada, Ottawa, Ontario.
number of orders and families (Gordh In 2001, 32.7% of eggs were parasi-
1979). We report on the occurrence of G. tized by an unidentified scelionid(s),
pennsylvanicum,A.pearsalli and Ooencyr- prompting a more systematic study in the
tus sp. in B.C. in a previously undocu- following year. In 2002, parasitoids
'Department ofBiological Sciences, Simon Fraser University, Bumaby, British Columbia, Canada V5A
1S6
^Current address: BIOCAP Canada Foundation, Queen's University, 156 Barrie St., Kingston, ON, Can-
ada K7L3N6, [email protected]
^Currentaddress: PheroTechInc., 7572 Progress Way, Delta, B.C. V4G 1E9Canada
144 J.Entomol. Soc.Brit.Columbia 101,December2004
emerged from ca. 29% of L. occidentalis B.C. seed orchards. Further study will be
eggs. Gryon pennsylvanicum was the necessary to identify the fullparasitic guild
predominant parasitoid, attacking 87% of of this insect, its temporal synchronicity
parasitized eggs. The remaining parasi- with L. occidentalis, and the density of
tized eggs were parasitized by Anastatus wasps required to reduce seed bug popula-
pearsaUi (8%) and an unidentified tions. Anastatus bifasciatus, which was
Ooencyrtiis sp. (Hymenoptera: Encyrti- introduced into the eastern U.S. to control
dae) (4%). One parasitoid failed to com- gypsy moth in the early 1900's (Grossman,
plete its development and was not identi- 1925), may form part ofthe natural enemy
fied. Leptoglossns occidentalis has not complex ofL. occidentalis in at least some
previously been recorded as a host for any regions ofNorthAmerica.
oftheseparasitoids. We thank Lubomir Masner and Gary
Natural rates of parasitism of L. occi- Gibson, Agriculture and Agri-Food Can-
dentalis eggs may vary at other times dur- ada, for parasitoid identification, and Chris
ing the season. In addition, the use ofeggs Walsh and Ward Strong, B.C. Ministry of
that were up to 7 d old may have affected Forests, for allowing us access to
the level ofparasitism, because older eggs Kalamalka Seed Orchard and providing
would have been acceptable to parasitoids advice. We also thank Andrea Battisti,
for a shorter period oftime. However, the Universita di Padova, Italy, for helpful
relatively high level ofparasitism observed discussion. This research was supported
in this study suggests that biological con- by the B.C. Ministry ofForests, the Natu-
trol with egg parasitoids could serve as a ral Sciences and Engineering Research
potential component of an integrated pest Council ofCanada, the Science Council of
managementprogram forL. occidentalis in B.C., and 21 forest companies.
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