Distribution and biology of Anisota manitobensis (Saturniidae) in southern Manitoba

4 Pages·2002·2.1 MB·English

by  Donald C Henne

JournaloftheLepidopterists'Society
56(1),2002,5-8
DISTRIBUTION AND BIOLOGY OFAN1SOTA MANITOBENSIS (SATURNIIDAE) IN
SOUTHERN MANITOBA
Donald C. Henne
DepartmentofEntomology, 402 Life Sciences Building, LouisianaState University, Baton Bouge, Louisiana70803, USA
ABSTRACT. Theknowndistributionofthesatumiidmoth,Anisotamanitobehsisislimitedtosouthern Manitobaandnorthern Minnesota.
To date, nothinghas been reported in the literature about adult emergence times andadult matingactivity. In this paper, the known distribu-
tion ofA. manitobensis in southern Manitobais summarized, informationon larval collection techniques is provided, and newinformation on
adultemergencetimes andadult matingactivities aregiven. Adultsbegin emergingatapproximately0600h (CDT),with afewdelayingemer-
gence until between 2100 and2200h (CDT). Adult females ofA. manitobensis call from 0630 to 0900 h (CDT) and, ifnot mated, again from
0100to0300h (CDT).
Additional keywords: Anisotastigma, buroak, callingfemales,larvae, oakworms.
The satumiid moth Anisota manitobensis McDun- employed in an effort to locate colonies ofA. manito-
nough is known from southern Manitoba, northern bensis in and around Winnipeg.
Minnesota, and may possibly occur in northeastern Anisota manitobensis larvae were maintained on fo-
North Dakota (McGugan 1958, Tuskes et al. 1996). liage of O. macrocarpa. Pupae were placed in moist
Anisota manitobensis was reported from Wisconsin by peat and overwintered at 5°C. Pupae were removed
Riotte and Peigler (1981). However, these records from cold storage in early May and placed in shaded
have been disputedbyTuskes et al. (1996). The known outdoor cages to ensure exposure to ambient temper-
distribution ofA. manitobensis is based largelyonvery atures andphotoperiod. Voucher specimens have been
old collection records. There are relatively few collec- retained in the personal collection ofdie author.
tion records for A. manitobensis, and almost none
Results
from the last 25years. Nothingwas known about adult
emergence times, adult female calling times, the Historical distribution (Fig. 1). According to the
length ofthe mating period, oroviposition behavior of relevant literature (McDunnough 1921, Brodie 1929,
this species. McGugan 1958, Ferguson 1972, Riotte & Peigler
This paper summarizes most ofthe available collec- 1981, Tuskes et al. 1996), and museum records B.
(J.
tion records for this moth in southern Manitoba. Wallis Museum of Entomology [JBWM], Manitoba
These locality records were utilized in an attempt to Museum of Man and Nature [MMMN], and the
locate this species in the field. In 1996, and again in Transcona Historical Museum [THM]),A. manitoben-
1997, A. manitobensis was collected at Fullers, Mani- sis has been collected at the following southern Mani-
toba. Larvaewere located onverysmallburoak (Quer- toba localities:
cus macrocarpa Michaux) trees, in semi-open areas. Anola: 26 June 1976 (Tuskes et al. 1996), Aweme
New information about adult emergence times and fe- (8 km north of Treesbank): 23 June 1904 (McDun-
male calling times indicate tiiat adults begin emerging nough 1921), 29 June 1907 and 4 July 1907 (McDun-
at approximately 0600 h (CDT). A few individuals de- nough 1921), ([larva] August 1912 [JBWM]), Birds
layed emergence until between 2100 and 2200 h Hill: 20 July 1963 (THM), Brandon: 15 July 1950
&
(CDT). Adult females of A. manitobensis call from (JBWM), Darlingford: (Riotte Peigler 1981), Kel-
0630 to 0900 h (CDT) and again from 0100 to 0300 h wood: (Riotte & Peigler 1981), Killarney: 10 July
(CDT), ifnot mated duringthe morningcallingperiod. 1947 (JBWM), McCreary: (Riotte & Peigler 1981),
Middlechurch: July 1954 (JBWM), Pine Bidge:
Materials and Methods (Riotte & Peigler 1981), Biding Mountain National
A search for colonies of Anisota spp. in southern Park: 19 June 1936 (Ferguson 1971), Sandilands
Manitoba was conducted annually from 1989 to 1996. Provincial Forest: 25 June 1971 (C. S. Quelch field
Using the available collection records, many ofthe lo- notes—THM), Souris: June 1954 (JBWM), 1 mi. W.
calities in Manitoba where species ofthis genus have Vivian: 30 June 1967 (C. S. Quelch field notes—
been collected in the past were extensively searched, THM), Winnipeg: July 1920 (JBWM), 10 June 1921
often on more than one occasion. With the exception and 16 June 1921 (JBWM), 8 June 1928 (JBWM), 29
ofa single locality record forA. virginiensis (Drury) at June 1928 (Brodie 1929), 3 July 1930 (JBWM), 22
Belair, Manitoba, efforts at locatingAnisota spp. (e.g., June 1948 (JBWM), 5 July 1949 (JBWM), 10July 1950
black lighting, searching for larvae) yielded no addi- (THM), 26 June 1954 and 2 July 1954 (THM), 14 July
tional colonies. Virgin females ofthe closely relatedA. 1955 (THM). Criddle (1932) reportedA. manitobensis
stigma Fabricius (courtesyofMr. R Turtle) were also from the areasouthofCarman,wherethree acresofbur
J.
Journal of the Lepidopterists' Society
pation. The same localitywas revisited in June 1997. A
cluster of 75 second-instar larvae was found on a ter-
minal oak leaf, only 30 cm above the ground and fac-
ingwest, in full sunlight, and along the forest-field in-
terface. Sixty-five pupae were obtained from this
collection (32 males, 33 females).
Morphological comparisons (Fig. 2). According
to Brodie (1929) mature A. manitobensis larvae pos-
sess pale tan head capsules. Examination ofthe larvae
collected near Fullers revealedthat the headcapsule is
clearly orange, as in mature larvae of the closely re-
&
lated A. stigma (Riotte Peigler 1981). In addition,
the single larva collected on 22 August 1996 differed
from the other two in that the dorsal stripe and shad-
Fig. 1. DistributionofAnisota manitobensis in southern Mani- ing described by Brodie were very faint and barely
toba. LocalityofmostrecentcollectionatFullersindicatedbyarrow. visible. Color photos ofthese larvae can be viewed at
http://www.lsu.edu/faculty/dhennel/. Brodie (1929)
also described the pupa ofA. manitobensis as reddish-
oakwere severely defoliated in 1931. Criddle also men- brown in color. Although this color was observed for
tioned Onah and Treesbank as other localities where the first few days following pupation, the pupae even-
A. manitobensis larvaewere collected that sameyear. tually darkened to a brownish-black color. Confirma-
New collection locales. On 20 August 1996, two tion ofthe larval collections as being A. manitobensis
late fifth-instar A. manitobensis larvae ofopposite sex was obtained the followingJune when adults emerged
were collected east ofFullers, Manitoba. This locality from over wintered pupae. Adults closely resembled
is approximately 5 km north of East Selkirk, along museum specimens of A. manitobensis. The speci-
highway #508. As with other saturniid larvae, larvae of mens obtained lacked anyheavyspotting ofthe wings,
Anisota can be sexed according to the presence or ab- atrait characteristic ofA. stigma. Examination ofmale
sence of a small dark spot on the venter ofthe ninth genitaliaofspecimens ofA. stigma from Anne Arundle
abdominal segment. This spot is associated with the Co., Maryland, compared with those ofthe specimens
male genitalhistoblast (Miller 1977). Larvaehavingthis collected at Fullers also confirmed the identity ofA.
spot are males and those lacking this spot are females. manitobensis.
These larvae were found feeding on the foliage of a Mating activity. Adult emergence times, female
small bur oak that was approximately 150-180 cm in calling times, length ofpairing, and oviposition habits
height. An egg cluster containing 16 eggs was located for A. manitobensis were unknown until this time.
on the tip of an oak leaf at the end of a branch, ap- Adults obtainedfrom these collections emerged in the
proximately 45 cm above ground level and facing morning, around 0600 h (CDT). Females began call-
south. Ofthese 16 eggs, 12 had eclosed and the other ing as soon as their wings were fully expanded, often
four contained dead embryos. On 22 August 1996 a within 30 minutes ofeclosion. Most females had their
second collection consisting ofa single late fifth-instar ovipositors everted from approximately0630 to 0900 h
female larva was also made, approximately 1 km west (CDT). If unmated during this time these females
of the first collection. This larva was also collected would exhibit a second calling time, from approxi-
from asmallburoaktree thatwas only75 cm in height mately 0100 to 0300 h (CDT). These calling times are
and >90% defoliated; no egg cluster was located. It similar to those reported for A. stigma (Tuskes et al.
was evidentthat several otherlarvae were also present 1996). Some adults delayed emergence until between
on this tree but had probably wandered away to pu- 2100 and 2200 h (CDT), which is shortly after sunset
pate. At both collection points, the oak trees on which in southern Manitoba during early June. Length of
these larvae were collected were isolated (i.e., >150 pairing at night was variable, ranging from one to sev-
cm) from othertrees, had low surroundingvegetation, eral hours. Adults matedduringthe morninghours re-
and were receiving full sunlight. In the laboratory, all mained in copula until dusk, at which time females
three larvae wandered for approximately two days af- would begin ovipositing. This behavior is very similar
ter feeding was completed, and pupated approxi- to that reported for A. stigma in Tuskes et al. (1996).
mately three days after wandering ceased. All larvae Oviposition behavior afterseparation ofadults was dif-
turned a mottled green color several days prior to pu- ficult to observe. Most females placed in paper sacks
Volume Number
56, 1
Fig. 2. Fifth-instarlarvaeofAnisota manitobensis. (A) lateralview, (B) dorsalview
afterpairingceased refusedto layeggs. A single female, variant ofA. stigma. Unfortunately, there is ahuge gap
however, deposited 185 eggs inside apaper sack, overa in collection records betweenA. manitobensis in Man-
three-dayperiod. Egg laying activitywas not observed. itoba and the nearest records for A. stigma in Min-
nesota andWisconsin. Material from this region could
Discussion
be useful in solvingthe question as towhetherA. man-
Anisota manitobensis was a very difficult species to itobensis should be recognized as a full species or not.
locate in the field. McGugan (1958) reportedA. mani- The failure ofA. stigma females to attractA. manito-
tobensis larvae as locallyabundant in some areas ofthe bensis males does not necessarily indicate that some
Red RiverValley ofsouthern Manitoba but also stated form of prezygotic isolating mechanism isolates the
that itis generallyfound in small numbers. This would two species. Instead, it maymean thatA. manitobensis
appear to be the case with the population at Fullers, was simply not present in the localities where A.
Manitoba. Evidence of bur oak defoliation typical of stigma females were deployed. Unfortunately, live-
feeding by larval Anisota was also noted near East stock ofA. stigma was not available to be tested on a
Selkirk, and in an area east ofWinnipeg, just south of known population ofA. manitobensis.
Pine Ridge. No larvae or egg clusters were found at
Acknowledgments
these localities. Gregarious larvae ofDatana ministra
(Drury) were common in these areas and were noted I would like to thank the following individuals for their helpful
for the similar method by which they defoliated bur comments, insights, and suggestions in reviewingthis manuscript:
R. S. Peigler(SanAntonio, Texas), K. Diehl and R. E. Roughley
oak. Larvae ofAnisota and Datana consume all ofthe (UniversityofManitoba), andtotheJ.followinginstitutions forallow-
oak leaf, with the exception ofthe midvein. Riotte and ingmetorecordspecimenlabel data:J. B.Wallis MuseumofEnto-
Peigler (1981:113) also found Datana to be common mology (University ofManitoba), Manitoba Museum of Man and
Nature, and the Transcona Historical Museum. I would also like to
and similarly interfered/confused their searching for thank Mr. Derek Bridgehouse forproviding specimens ofAnisota
Anisota. It was also noted that agricultural areas now stigma from Maryland and Mr. Helios Hernandez (Manitoba De-
isolate many of the localities where A. manitobensis partmentofNaturalResources)forassistanceinobtainingnecessary
scientific research andcollectingpermits to studyAnisota in Mani-
was collected in the past. Local extirpations ofthis in- tobaProvincial Parks. I am also gratefulto Ms. StacyClayton (LSU
sect have likely occurred on a large scale, but it is be- DepartmentofEntomology) forassistance inpostingdieweb site.
yond the scope ofthis paperto speculate on the popu-
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