THE BERTHA ARMYWORM, MAMESTRA CONFIGURATA (LEPIDOPTERA: NOCTUIDAE). MORTALITY OF IMMATURE STAGES ON THE RAPE CROP, 1972–1975

1977 ◽  
Vol 109 (6) ◽  
pp. 823-837 ◽  
Author(s):  
H. G. Wylie ◽  
G. E. Bucher

AbstractLarvae of bertha armyworm, Mamestra configurata Walk., collected in 1972–75 on rapeseed in the prairie provinces of Canada (predominantly in Manitoba), were killed by one virus, one fungus, one microsporidium, seven insect parasites, and by other factors. Mortality from disease was about 24% in 1972 when bertha armyworm was abundant, but much lower in succeeding years after the host’s population density declined. The most important hymenopterous parasite, Banchus fiavescens Cress., was relatively rare in 1972 but subsequently killed over 40% of the host larvae each year. A tachinid, Athrycia cinerea (Coq.), killed over 20% of the mature bertha armyworms in each generation. Each of the other five parasite species was associated infrequently with M. configurata. Details of the biology of each pathogen and parasite are presented. About 12% of the mature host larvae died because they failed to empty the gut, with subsequent penetration of the gut wall by bacteria, or because they did not form a morphologically-sound pupa. Pupae of M. configurata died in the soil following penetration of the gut wall by bacteria, as a result of soil cultivation, and from low temperatures in winter. No pathogens or parasites were recorded in field-collected pupae, though an ichneumonid, Ichneumon canadensis Cress., parasitized pupae in a field cage and may occasionally do so in natural conditions. No pathogens or parasites of bertha armyworm eggs were recorded. A preliminary survival model for bertha armyworm, based on estimates of mortality from various causes identified in this study, is presented. The possibility of preventing or reducing future oubreaks of M. configurata by colonizing additional parasite or pathogen species in the prairie provinces is discussed.

1977 ◽  
Vol 109 (5) ◽  
pp. 747-754 ◽  
Author(s):  
H.G. Wylie

AbstractAthrycia cinerea (Coq.) is a univoltine parasite of bertha armyworm, Mamestra configurata Wlk., on rapeseed in the Prairie Provinces of Canada. Details of the parasite’s seasonal life history are presented. Females oviposit on third, fourth, fifth, and sixth instars of bertha armyworm, and the parasite larvae usually develop gregariously and mature on the fifth and sixth instars. Supernumerary parasite larvae on superparasitized hosts starve; surviving larvae develop more rapidly, form smaller pupae with a lower capacity for survival, and eventually produce a consistently though not significantly smaller percentage of female adults than parasites that develop on non-superparasitized hosts. Larvae of A. cinerea are often killed if they compete with larvae of Banchus flavescens Cress., the only other common parasite of bertha armyworm, and a small percentage of the pupae of A. cinerea are killed by a hyperparasitic ichneumonid, Phygadeuon subfuscus Cress.


1999 ◽  
Vol 131 (1) ◽  
pp. 11-28 ◽  
Author(s):  
James E. O’Hara

AbstractThe bertha armyworm, Mamestra configurata Walker, causes periodic but severe damage to canola crops in North America, particularly in the Canadian provinces of Alberta, Saskatchewan, and Manitoba. This paper provides information on the tachinid flies (Tachinidae: Diptera) recorded from bertha armyworm in North America. A key to adults is provided for separation of the genera, and each species known from bertha armyworm is characterized with respect to recognition, biology (including hosts), and distribution. The species included are Athrycia cinerea (Coquillett), Blondelia sp., Chetogena claripennis (Macquart) species complex, Chetogena tachinomoides (Townsend) (new record), Eurithia consobrina (Meigen), Exorista mella (Walker), Lespesia archippivora (Riley), Panzeria ampelus (Walker), Phryxe pecosensis (Townsend), Phryxe vulgaris (Fallén), Spallanzania hebes (Fallén) (new record), Winthemia rufopicta (Bigot), and Winthemia quadripustulata (Fabricius). Eurithia consobrina is a Palearctic species that has been introduced into Canada for control of M. configurata but is probably not established; it is included here in the event it is introduced again and establishment is achieved.


1979 ◽  
Vol 111 (1) ◽  
pp. 91-95 ◽  
Author(s):  
Warren Steck ◽  
E. W. Underhill ◽  
M. D. Chisholm ◽  
C. C. Peters ◽  
H. G. Philip ◽  
...  

AbstractTraps baited with the sex pheromone of the bertha army worm moth, Mamestra configurata (Walker), were operated at 36 sites across the prairie provinces in 1976 and 1977. They captured ca. 15 times as many bertha moths as did light traps and were considered to constitute a useful method for detection of adults of this species.


1979 ◽  
Vol 111 (6) ◽  
pp. 747-748 ◽  
Author(s):  
H.G. Wylie ◽  
G.L. Ayre

Banchus flavescens Cress. and Athrycia cinerea (Coq.) were reared each year (1972–1975) from larvae of bertha army worm, Mamestra configurata Walk. (Lepidoptera: Noctuidae), collected during an outbreak of this species on rapeseed in Manitoba. Neither parasite was reared from other Lepidoptera collected at that time from rapeseed; two separate attempts to propagate the parasites on native Lepidoptera other than M. configurata were unsuccessful (Wylie and Bucher 1977; Ewen and Arthur 1976). Since 1975 M. configurata has been rare in Manitoba. In 1976 both B. flavescens and A. cinerea were reared from bertha armyworm larvae from temporary artificial populations on rapeseed at Glenlea, south of Winnipeg. The presence of the two parasites in this locality, where M. configurata was not found during the outbreak, suggested that both B. flavescens and A. cinerea parasitize other lepidopterous species in Manitoba, especially when bertha armyworms are not present.


1984 ◽  
Vol 116 (2) ◽  
pp. 257-267 ◽  
Author(s):  
W. J. Turnock ◽  
R.J. Bilodeau

AbstractThe survival of Mamestra configurata Wlk. was determined from autumn and spring samples in 1973/74, 1980/81, and 1981/82 taken from unfilled and tilled portions of 12 fields of canola (Brassica campestris L. and B. napus L.). Survival from the pre-pupal stage in the autumn to post-diapause pupae in the spring varied from 2.9 to 56.5% in unfilled soil and from 0 to 25.4% in tilled soil. In untilled soil, the variations among fields in total mortality of M. configurata were related to parasitism by Banchus flavescens and to overwintering mortality. In tilled soil, overwintering mortality accounted for most of the variability in total mortality among fields. The percentage of mortality from injury to pupae, and their disappearance following tillage, greatly increased but this type of mortality did not account for much of the variability in total mortality. The disappearance of pupae following tillage was attributed to predation. In both untilled and tilled soils, the amount of overwintering mortality was related to the depth of accumulated snow, and mortality was lower in untilled soil because the stubble trapped more snow. The survival of M. configurata was not related to soil type, the type of tillage equipment, or the frequency of tillage. The number of adults emerging from untilled and tilled soil in one field were 2.58 and 0.27/m2 for M. configurata, 5.22 and 2.85/m2 for the parasite B. flavescens, and 4.46 and 3.60/m2 for the parasite Athrycia cinerea, indicating that the survival of the parasites was less affected by tillage than that of their host.Tillage may reduce the frequency and severity of outbreaks of M. configurata not only by increasing mortality but also by differentially affecting the survival of its main parasites.


1988 ◽  
Vol 120 (5) ◽  
pp. 401-413 ◽  
Author(s):  
W. J. Turnock

AbstractPopulations of larvae of the bertha armyworm, Mamestra configurata Wlk., in four physiographic regions of Manitoba showed similar trends over time: a decline from the outbreak of 1971–1972 to very low densities in 1975–1977, an increase to a peak during the years 1979–1981, and a subsequent decline. During the period of peak larval populations, brief (1 or 2 years) outbreaks [at least some fields with > 20 larvae per square metre) occurred at five locations in two regions, the Swan River Plain and the Valley River Plain, but not in the Western Uplands or the Manitoba Lowlands. In the first two regions, larval densities rose rapidly (from < 1.6 to > 13.8/m2) in 1 year. Although the general trend of population density was similar, there were differences in density among and within regions, and in the timing, severity, and duration of peak populations. Two parasitoids (Banchus flavescens Cress., Athrycia cinerea (Coq.)) and two pathogens (a nuclear polyhedrosis virus (NPV) and fungi of the Entomophthorales) occurred regularly in larval populations. Of these, B. flavescens had the highest constancy among collections and may help to keep bertha armyworm populations at low densities. NPV was rarely found among larvae from low-density populations but appeared in all populations that reached outbreak levels. No single biotic agent could be associated with the population declines because of multiple parasitism and the difficulty in partitioning mortality when only a single sample could be taken. The rapid increase of bertha armyworm larvae from very low to outbreak levels in 1 year will prevent predictions of outbreaks from being based on larval densities in the preceding year.


1983 ◽  
Vol 115 (8) ◽  
pp. 1039-1042 ◽  
Author(s):  
B. M. Hegdekar

AbstractThe critical photoperiod for diapause induction in pupae of Mamestra configurata Walker in Manitoba was 16 h 06 min at Glenlea (49°38′ N), 16 h 20 min at Grandview (51°10′ N), and 16 h 42 min at Birch River (52°24′ N). The differences in cirtical photoperiods observed at Glenlea and Grandview were not significant. At least two different photoperiods exist, one in the Glenlea and Grandview areas and the other in the Birch River area. In the laboratory, the critical photoperiod was 13.5 h when larvae were exposed to a daily fluctuating temperature regime of 12 h at 25 °C and 12 h at 10 °C. Longer critical photoperiods found for the field populations may be related to the relatively low ambient temperatures to which the larvae were exposed in field cages.


1986 ◽  
Vol 118 (12) ◽  
pp. 1221-1230 ◽  
Author(s):  
M.A. Howlader ◽  
G.H. Gerber

AbstractThe effects of age, egg development, and mating on calling behavior of the bertha armyworm, Mamestra configurata Walker, were studied at 20°C, 60% RH, and a 16-h L: 8-h D photoperiod. Most virgin females called and copulated for the first time during the second or third scotophase after emergence. The first copulation was 17.0 ± 0.2 h (mean±SE) long and was terminated within 1 h after lights off in the scotophase following the initiation of copulation. The ovaries contained the first chorionated eggs before the beginning of the second scotophase after emergence. The first egg laying occurred during the same scotophase in which the first copulation was terminated, i.e. scotophase three or four. Almost 75% of the eggs were laid by the end of the seventh scotophase after emergence. Mated females resumed calling after a refractory period of about 2 days. Once calling was resumed after copulation, most females laid eggs and called nightly, with egg laying occurring during the first 5–6 h and calling during the last 2–3 h of the scotophase. Mated females called for a shorter period during each scotophase than virgin females of the same age (1–3 h vs. 4–6 h). In virgin females, the diel periodicity of calling was advanced and the length of the daily calling period was increased with age until the seventh scotophase after emergence; thereafter, both remained relatively unchanged.


1972 ◽  
Vol 104 (11) ◽  
pp. 1745-1750 ◽  
Author(s):  
Y. W. Lee ◽  
R. J. Ford ◽  
H. McDonald ◽  
K. S. McKinlay ◽  
L. G. Putnam ◽  
...  

AbstractResidues of methomyl in rape plants and seed were determined after its application for bertha armyworm control. In one experiment application of 3 oz of methomyl per acre left 17 p.p.m. residue on the rape plants immediately after application. This level rapidly declined to 1.5, 1.0, 0.4, and 0.2 p.p.m. 1, 2, 5, and 9 days later, respectively, and no residue was detected (less than 0.02 p.p.m.) in seed harvested 22 days after application of the toxicant. Rape plant samples collected from several farms immediately after the application of 3 to 4 oz of methomyl per acre had 2.5 to 16 p.p.m. residues, indicating inefficient application of the insecticide in some cases. Analysis of rape seed samples collected from 36 farms showed little residue in three samples (0.02 to 0.03 p.p.m.) and none in 33, indicating that the use of methomyl for bertha armyworm control is not likely to contaminate rape seed with undesirable levels of residues.


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