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An identification key to hymenopteran parasitoids on cutworms
in field crops in the Canadian Prairies
R.W.M.Udari M. Wanigasekara, Andrés Herrera-Flórez, and Barbara J. Sharanowski
Department of Entomology, Faculty of Agricultural and Food Sciences, University of Manitoba, Canada.
Introduction
Materials and Methods
Results
Conclusions
References
Acknowledgments
1. Small body size (1.0—2.0 mm);
forewing with reduced venation,
no enclosed cells (Fig. 1)
Encyrtidae
(2)
1’. Large body size (>3.0 mm);
forewing with numerous veins and
at least two enclosed cells (Fig. 2)
3
•Cutworms cause economic damage to canola across the Canadian prairies every
year. Cutworms are difficult to control in agricultural crops as they are subterranean
and nocturnal and are usually sporadically distributed within fields.
•Parasitoid wasps are one of the most important natural enemies of arthropods in
natural environments. However, the parasitoid species attacking cutworms and the
phenology of these parasitoids have not been well documented.
•Although there has been some work on parasitoids (Schaaf 1972; Turnock et al.
1993), there are no taxonomic resources for the identification of parasitoids
attacking cutworms or the parasitoids found in canola in general.
• Without identification keys or appropriate taxonomic resources, the parasitoids
attacking cutworms will remain an underutilized natural resource.
•To develop an identification key to common Hymenopteran parasitoids of
cutworms in field crops
Objective
Field Collection and Rearing
Cutworm samples from infested field crops in Manitoba, Saskatchewan and
Alberta from 2013-2015. Following the methods outlined in Shaw (1997),
cutworms were individually reared in the laboratory until parasitoids wasps
emerged.
Identification
Parasitoids were identified using taxonomic keys (Gibson et.al, 1997, Wharton
et.al, 1997, Goulet and Huber 1993). Identifications were confirmed by sending
specimens to the Canadian National Collection (CNC). Images were taken with a
Nikon D5200 camera attached to an Olympus SZX16 microscope and a Canon
EOS 7D (with a Canon Macro Lens MP-E 65mm and a Canon Macro Lens EF 100
mm) camera attached to a Copy Stand CS-170 Tripod, plugged to a Stack Shot
System. Images were taken at multiple levels of focus, and stacked into a single
image using the program Helicon Focus 6 (Helicon Soft Ltd 2014).
Fig 1. Forewing without enclosed cells
Fig 2. Forewing with at least two
enclosed cells
2 (1) Ovipositor barely extended, not
visible from dorsal view (Fig. 3)
Copidosoma bakeri
(Howard, 1898)
2’ Ovipositor exerted 0.15-0.25 x
length of metasoma, readily
visible from dorsal view (Fig. 4)
Copidosoma
cuproviridis
Springate & Noyes
1990.
Fig 3. Ovipositor barely extended
Fig 4. Ovipositor exerted 0.15-0.25 x length of
metasoma
Results (continued)
3(1)
.
Forewing vein 2m-cu absent,
Rs+M present (Fig. 5a);
metasomal tergite 2 and 3
fused to form a inflexible
junction (Fig. 5b)
Braconidae
(4)
3’. Forewing vein 2m-cu present,
Rs+M absent (Fig. 6a) ;
metasomal tergite 2 and 3
separated to form a flexible
junction (Fig. 6b)
Ichneumonidae (8)
a
Rs+M
b
a
2m-cu
b
Fig 5. (a) Forewing vein 2m-cu absent, Rs+M present
(b) Metasomal tergite 2 and 3 fused
Fig 6. (a) Forewing vein 2m-cu present, Rs+M absent
(b) Metasomal tergite 2 and 3 separated
4(3). Occipital carina absent (Fig. 7)
5
4’. Occipital carina present (at least partially)
(Fig. 8)
Meteorinae
Meterous spp.
Fig 7. Occipital carina absent
Fig 8. Occipital carina present
5(4).
Forewing with distinct non sclerotized
radial vein (Fig. 9), small second
submarginal cell; Antenna with 16
flagellomeres (may appear as 32); first
metasomal tergum with spiracle on
laterotergite
Microgastrinae
(6)
5’. Forewing with distinct tubular sclerotized
radial vein (Fig 10), distinct trapezoid
shaped second submarginal cell; Antenna
with more than16 flagellomeres ; first
metasomal tergum with spiracle on
median tergite.
Macrocentrinae
Macrocentrus
innuitorum
Walley, 1936
Fig 9. Forewing with distinct non sclerotized radial vein
Fig 10. Forewing with distinct tubular sclerotized radial
vein
6(5). Propodeum ruguose with median
carinae present but obscured
partially by rugulae
7
6’. Propodeum punctate with obvious
median carinae
Sathon neomexicanus
(Muesebeck, 1921)
Fig 11. Propodeum ruguose with partially obscured
median carinae
Fig 12. Propodeum punctate with obvious median
carinae
7 (6). Forewing with 2r-m crossvein absent,
areolet absent (Fig. 13a); T2 rugulose
(Fig. 13)
Cotesia sp.
7’. Forewing with 2r-m crossvein
present, enclose areolet (Fig. 14a); T2
smooth (Fig. 14b)
Microplitis sp.
Fig 13. (a) Forewing vein 2r-m
crossvein absent
(b) T2 rugulose
Fig 14. (a) Forewing vein 2r-m
crossvein present
(b) T2 smooth
8(7). Metasoma with tergite 1 (T1) with spiracle
at or before the middle (Fig. 15)
9
8’. Metasoma with tergite 1 (T1) with spiracle
behind the middle (close to the apex) (Fig.
16)
10
Fig 16. Metasoma with tergite 1 (T1) with spiracle
behind the middle
Fig 15. Metasoma with tergite 1 (T1) with spiracle at
or before the middle
9 (8). The distance between eye and lateral
ocellus smaller than the diameter of the
ocellus (Fig 17); tarsal claws comb shaped;
mandibles with upper tooth longer than
lower
Tryphoninae
Netelia ocellata
(Viereck, 1909)
9’. The distance between eye and lateral
ocellus larger than or equal to the
diameter of the ocellus (Fig 18); tarsal
claws not comb shaped; mandibles with
similar sized teeth
Banchinae
Exetastes syriacus
Schmiedeknecht,
1910
Fig 17. Ocelli big and close to the eye
Fig 18. Ocelli smaller and not closer to the eye
10(9). Margin of the clypeus flat (truncate)
(Fig 19); metasoma depressed (wider than
higher)
Ichneumoninae
(12)
10’. Margin of the clypeus convex (Fig);
Metasoma laterally compressed (higher
than wider)
11
11 (10). Propodeum without areola; distance
between occipital carina and lateral
ocellus smaller than diameter of the
ocellus
Anomaloninae
(Erigorgus sp. )
11’. Propodeum areolate with area of
superomedia fully ended (completely
defined) (Fig. 21); occipital carina apart
from posterior ocellus by a larger
distance than the diameter of the ocellus
Campopleginae
(Campoplex spp.)
Fig 21. Propodeum areolate with
area of superomedia fully ended
12 (10). Apex of hypopygium developed in to a
lobular process (Fig. 22)
Spilichneumon sp.
12’. Apex of hypopygium not developed in
to a lobular process (apex from slightly
concave to straight) (Fig. 23)
13
Fig 22. Apex of hypopygium
developed in to a lobular process
Fig 23. Apex of hypopygium not
developed in to a lobular process
13 (12) Areola longer than wide, semi-elipitacal
or hexagonal
Diphus sp.
13’ Areola subquadrate, almost as long as
wide (Fig. 24)
Ichneumon sp
(14)
14 (13’) Areola indistinct, without a distinct
anterior transverse carina; posterior
transverse carina curved (Fig. 25)
Ichneumon sp. 1
14’ Areola distinct, with a distinct anterior
transverse carina; posterior transverse
carina straight (Fig. 26)
Ichneumon sp. 2
Fig 19. Margin of the clypeus flat
Fig 20. Margin of the clypeus flat
1. Gibson, G.A., Huber, J.T.,and Woolley, J.B. 1997. Annotated keys to the genera of Nearctic
Chalcidoidea (Hymenoptera). NRC Research Press, Ottawa.
2. Goulet, H.,and Huber, J.T. 1993. Hymenoptera of the world: an identification guide to families.
Research Branch, Agriculture Canada.
3. Schaaf, A. 1972. The parasitoid complex of Euxoa ochrogaster (Guenee)(Lepidoptera: Noctuidae).
Quaest Entomol, 8: 81-120.
4. Shaw, M.R. 1997. Rearing parasitic hymenoptera. Amateur Entomologists' Society.
5. Turnock, W., Timlick, B.,and Palaniswamy, P. 1993. Species and abundance of cutworms (Noctuidae)
and their parasitoids in conservation and conventional tillage fields. Agriculture, ecosystems &
environment, 45(3): 213-227.
6. Wharton, R.A., Marsh, P.M.,and Sharkey, M.J., (eds.) 1997. Manual of the New World genera of the
family Braconidae (Hymenoptera). International Society of Hymenopterists, Washington, DC.
The authors are deeply grateful to Dr. Jose Fernandez-Triana, Dr. Andrew Bennett and Dr. Gary
Gibson (Canadian National Collection, Ottawa, Canada) for species identification, and also thank
Leah Irwin for taking pictures. Further, we will thank Dr. Kevin Floate, Jenifer Otani, Jeremy
Hummel, Dr. John Gavloski, and Manitoba farmers for providing us specimens. Finally, we would
like to thank all the summer students worked in Sharanowski’s lab from 2013-2015.
•Correct identification of natural enemies is crucially important for safe and efficient biological
control programs.
• A few of the parasitoids reared from cutworms were unidentifiable to species due to a lack of
taxonomic knowledge of the genus. This highlights the need to increase bioliteracy of parasitic
wasps through taxonomic research.
•This key will be very useful for researchers and agronomists to identify common hymenopteran
parasitoids on cutworms in field crops in the Canadian Prairies, which will hopefully facilitate future
biological control programs.
a b
b
a
2r-m
Radial vein
Radial vein
Fig 25. Propodeum, arrow pointing to
posterior transverse carina.
Fig 26. Propodeum, red arrow pointing to
posterior transverse carina; blue arrow
pointing to areola.
Fig 24. Areola subquadrate, almost
as long as wide
