SIZE DIFFERENCES OF LABORATORY REARED AND WILD POPULATIONS OF TRICHOGRAMMA MINUTUM (HYMENOPTERA: TRICHOGRAMMATIDAE)

1982 ◽  
Vol 114 (8) ◽  
pp. 693-698 ◽  
Author(s):  
Susan G. Southard ◽  
Mark W. Houseweart ◽  
Daniel T. Jennings ◽  
William A. Halteman
Keyword(s):  
First Generation ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Head Width ◽  
Wild Populations ◽  
Body Dimensions ◽  
Female Parasitoid ◽  
Trichogramma Minutum ◽  
Three Body ◽  
Large Host

AbstractThree body dimensions (body length, head width, and abdomen width) were used to determine size differences between laboratory-reared and wild populations of Trichogramma minutum Riley. Six separate groups of T. minutum were measured: three groups were from Sitotroga cerealella (Olivier) eggs, two from spruce budworm Choristoneura fumiferana (Clemens) eggs, and one from wild populations of spruce budworm.Female T. minutum from spruce budworm (large host) eggs were significantly larger for all body dimensions than T. minutum from S. cerealella (small host) eggs. Male T. minutum from field-collected spruce budworm eggs were significantly larger for all body dimensions than T. minutum reared for more than one generation in S. cerealella eggs.A significant reduction in female parasitoid size was observed during the initial generations of T. minutum reared in the smaller host (S. cerealella). However, this size reduction was not permanent. Following numerous generations in the S. cerealella host eggs, a significant increase in female parasitoid size was noted within the first generation of T. minutum reared in the spruce budworm host eggs.

GROUND RELEASES OF TRICHOGRAMMA MINUTUM RILEY (HYMENOPTERA: TRICHOGRAMMATIDAE) AGAINST THE SPRUCE BUDWORM (LEPIDOPTERA: TORTRICIDAE)

1987 ◽  
Vol 119 (3) ◽  
pp. 251-263 ◽  
Author(s):  
S.M. Smith ◽  
M. Hubbes ◽  
J.R. Carrow
Keyword(s):  
Optimal Strategy ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Egg Mass ◽  
Northern Ontario ◽  
Inundative Release ◽  
Egg Masses ◽  
Trichogramma Minutum ◽  
Spruce Stands ◽  
Natural Parasitism

AbstractDuring 1982 and 1984, ground releases of Trichogramma minutum Riley were assessed for control of the spruce budworm, Choristoneura fumiferana (Clemens), on 12- to 20-year-old, white spruce stands in northern Ontario. Maximum parasitism of susceptible egg masses was 16 and 87% following the release of 480 000 and 12 million female T. minutum per hectare, respectively. Releases at intervals of 1 week maintained parasitism of susceptible egg masses at constant levels throughout the oviposition period of spruce budworm. When parasitism of susceptible egg masses was maintained above 78.2% during the ovipositional period, total egg mass parasitism averaged 58.0% and resulted in an 80.3% reduction of overwintering 2nd-instar larvae. The optimal strategy for reducing spruce budworm was two releases of T. minutum at an interval of 1 week in the ovipositional period. This allowed a second generation of parasitoids to emerge from the spruce budworm eggs that were more efficient in maintaining high levels of parasitism than those emerging from the standard rearing host. Natural parasitism of spruce budworm egg masses was less than 4% and there was no carryover of parasitism in the years following inundative release. The rate of T. minutum release necessary to achieve effective mortality of spruce budworm during outbreak populations is discussed briefly.

From branch to bench: establishing wild spruce budworm populations into laboratory colonies for the exploration of local adaptation and plasticity

2021 ◽  
Vol 153 (3) ◽  
pp. 374-390 ◽  
Author(s):  
K. Perrault ◽  
A.A. Wardlaw ◽  
J.N. Candau ◽  
C.L. Irwin ◽  
M. Demidovich ◽  
...  
Keyword(s):  
Regional Variation ◽  
Life History Traits ◽  
Choristoneura Fumiferana ◽  
Common Garden ◽  
Spruce Budworm ◽  
Population Differences ◽  
Wild Populations ◽  
Laboratory Colonies ◽  
Common Garden Experiments ◽  
Disease Free

AbstractSpruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), is a destructive defoliator found throughout the Nearctic boreal forest. This pest has a broad geographic range and shows regional variation in key life history traits. These population differences may represent important adaptations to local environmental conditions and reflect underlying genetic diversity. Existing laboratory colonies of spruce budworm do not capture this regional variation, so we established five new spruce budworm colonies from across its range to explore regional adaptations among spruce budworm populations within common garden experiments. We present methods for establishing new spruce budworm laboratory colonies from wild populations. We describe the process of flushing, rearing, and disease screening used on these new populations to produce healthy disease-free laboratory stocks.

3.5 SUPPRESSION OF SPRUCE BUDWORM POPULATIONS BY TRICHOGRAMMA MINUTUM RILEY, 1982–1986

1990 ◽  
Vol 122 (S153) ◽  
pp. 56-81 ◽  
Author(s):  
S.M. Smith ◽  
D.R. Wallace ◽  
G. Howse ◽  
J. Meating
Keyword(s):  
Choristoneura Fumiferana ◽  
Host Density ◽  
Spruce Budworm ◽  
Mass Rearing ◽  
Egg Parasitoid ◽  
Curvilinear Relationship ◽  
Egg Masses ◽  
Trichogramma Minutum ◽  
Egg Parasitism ◽  
Release Timing

AbstractThe ability of the egg parasitoid, Trichogramma minutum Riley, to suppress outbreak populations of the spruce budworm, Choristoneura fumiferana (Clemens), was studied annually near Hearst, Ont., from 1982 through 1986. Timing of broadcast parasitoid-releases was linked to spruce budworm moth emergence and oviposition. These phenological relationships were predicted from a regression based on larval development at least 2 weeks before expected emergence; this allowed sufficient time to regulate (program) parasitoid emergence during mass-rearing. Emergence of caged spruce budworm adults was used to monitor moth eclosion in the field. Pheromone traps provided daily information on the activity of male moths and helped to synchronize the parasitoid releases with spruce budworm oviposition. Information on parasitoid activity was obtained from sentinel (laboratory-reared) and naturally occurring spruce budworm egg masses. A curvilinear relationship between the rate of parasitoid release and parasitism of sentinel egg masses was developed. Two parasitoid releases, 1 week apart, early in the oviposition period of spruce budworm, significantly increased parasitism of host eggs by 14–83% and reduced larval populations correspondingly from 42 to 82%. Single releases were less effective and increased parasitism by 0.3–52% (single ground release, 1986). Two parasitoid releases, combined with a spring application of Bacillus thuringiensis Berliner to larval populations, was the most effective strategy and resulted in 83% egg parasitism and 93% larval reduction. Release rates greater than 12–16 × 106 ♀ ♀ T. minutum per hectare were not warranted based on impact and costs. The effects of release timing, weather, host density, and parasitoid quality on the future successful use of T. minutum are discussed.

FIELD RELEASES OF TRICHOGRAMMA MINUTUM (HYMENOPTERA: TRICHOGRAMMATIDAE) FOR SUPPRESSION OF EPIDEMIC SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE), EGG POPULATIONS IN MAINE

1984 ◽  
Vol 116 (10) ◽  
pp. 1357-1366 ◽  
Author(s):  
Mark W. Houseweart ◽  
Daniel T. Jennings ◽  
Robert K. Lawrence
Keyword(s):  
Point Source ◽  
Choristoneura Fumiferana ◽  
Single Point ◽  
Spruce Budworm ◽  
Point Sources ◽  
Slight Improvement ◽  
Parasitism Rates ◽  
Trichogramma Minutum ◽  
Multiple Releases ◽  
Better Than

AbstractTrichogramma minutum Riley was released in the field for suppression of epidemic spruce budworm, Choristoneura fumiferana (Clemens), egg populations in Maine from 1977 to 1981. Commercially reared California-strain T. minutum were released from the ground at single-point sources in 1977. In 1978, using 4-point-source releases, we found that the native Maine-strain performed better than the California strain. In 1979, broadcast and multiple releases from the ground gave slight improvement in parasitism over 4-point releases. In 1981, three closely timed, aerially broadcast releases from a helicopter yielded increases in parasitism rates significantly higher than those in control plots, but not sufficient to suppress epidemic spruce budworm populations. Important variables and suggestions for future aerial releases are discussed.

THE EFFECTS OF ZECTRAN ON THE PARASITOIDS OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

1974 ◽  
Vol 106 (5) ◽  
pp. 545-554 ◽  
Author(s):  
D. E. Leonard ◽  
G. A. Simmons
Keyword(s):  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Lower Percentage ◽  
Aerial Application ◽  
Percentage Parasitism ◽  
Trichogramma Minutum ◽  
Absolute Population ◽  
Population Numbers

AbstractWhere the insecticide Zectran was used to protect foliage from feeding of the spruce budworm, Choristoneura fumiferana (Clemens) (Lepidoptera: Tortricidae), the per cent parasitism of dipteran parasitoids (Tachinidae) showed a statistically significant lower value. In treated areas, the per cent parasitism of the hymenopteran Ephialtes ontario (Cresson) (Ichneumonidae) was lower; Meteorus trachynotus Viereck was about the same; Apanteles fumiferanae Viereck, Glypta fumiferanae (Viereck) (Braconidae), and Trichogramma minutum Riley (Trichogrammatidae) were greater. None of these differences was statistically significant. Results were consistent for the 2 years of study with the exception of E. ontario which showed a significant lower percentage parasitism in areas treated 1 year. Absolute population numbers of parasitoids were lower than is suggested by comparisons of apparent parasitism levels. The lowest absolute numbers were found in tachinids and E. ontario. Parasitic hymenopterans and dipterans were among the adult insects killed by the aerial application of Zectran but none of the species collected was a major spruce budworm parasitoid.

SIMULATED MANAGEMENT OF AN HISTORICAL SPRUCE BUDWORM POPULATION USING INUNDATIVE PARASITE RELEASE

1990 ◽  
Vol 122 (6) ◽  
pp. 1167-1176
Author(s):  
M. You ◽  
S.M. Smith
Keyword(s):  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Integrated Approach ◽  
Light Level ◽  
Green River ◽  
Egg Parasite ◽  
Life Table Data ◽  
Trichogramma Minutum ◽  
Table Data ◽  
Inundative Releases

AbstractSummary life table data of historical spruce budworm, Choristoneura fumiferana (Clemens), populations from the Green River Project in New Brunswick, Canada (1947–1958), provided information for developing a management strategy using annual inundative releases of the egg parasite Trichogramma minutum Riley. Three threshold levels (39, 169, and 201 budworm egg masses per 10 m2 foliage) were assigned to the spruce budworm population and a simulation model employed to manage it at or below each level. Based on field data, the lowest threshold represented a light level of defoliation while the other two thresholds represented moderate defoliation levels. With the exception of 3 years at the low level, annual inundative releases of T. minutum successfully suppressed the spruce budworm population below the three thresholds in the model. Annual releases of T. minutum were also simulated during the inclining, plateau, and declining phases of one outbreak cycle of the spruce budworm. At the same rate (12 × 106 female T. minutum per hectare), inundative releases during the inclining phase were more effective than during either the plateau or declining phases. The results suggest that some low and moderate populations of spruce budworm can be effectively managed using annual inundative releases of an egg parasite, particularly toward the end of the inclining phase of an outbreak, but when populations reach severe levels, additional mortality agents probably will have to be considered in an integrated approach.

DEVELOPMENT RATES OF TRICHOGRAMMA MINUTUM (HYMENOPTERA: TRICHOGRAMMATIDAE) AND IMPLICATIONS FOR TIMING AUGMENTATIVE RELEASES FOR SUPPRESSION OF EGG POPULATIONS OF CHORISTONEURA FUMIFERANA (LEPIDOPTERA: TORTRICIDAE)

1985 ◽  
Vol 117 (5) ◽  
pp. 557-563 ◽  
Author(s):  
Robert K. Lawrence ◽  
Mark W. Houseweart ◽  
Daniel T. Jennings ◽  
Susan G. Southard ◽  
William A. Halteman
Keyword(s):  
Host Species ◽  
Choristoneura Fumiferana ◽  
Spruce Budworm ◽  
Oviposition Period ◽  
Sitotroga Cerealella ◽  
Development Rates ◽  
Trichogramma Minutum ◽  
Augmentative Releases ◽  
Parasitoid Development

AbstractDevelopment rates of the parasitoid, Trichogramma minutum Riley, were studied to provide information required in timing field releases of T. minutum for suppression of egg populations of the spruce budworm, Choristoneura fumiferana (Clemens). Development was observed in eggs of 2 host species, C. fumiferana and Sitotroga cerealella (Olivier), at constant temperatures of 14, 21, and 27 °C. Parasitoid development varied directly with temperature. Parasitoids developed more rapidly in eggs of S. cerealella than in those of C. fumiferana. Parasitoid males developed faster than females in some host-temperature treatments. Development of T. minutum is apparently rapid enough to allow progeny of parasitoids released early in the spruce budworm's oviposition period to mature and be available to oviposit in budworm eggs deposited later in the budworm oviposition period. Potential release strategies are discussed.

Derivation of Pheromone-Based Larval Thresholds in Spruce Budworm Accounting for Distance to Defoliated Forest Stands

2021 ◽  
Author(s):  
Marc Rhainds ◽  
Ian DeMerchant ◽  
Pierre Therrien
Keyword(s):  
Boreal Forests ◽  
Large Scale ◽  
Choristoneura Fumiferana ◽  
Intervention Strategy ◽  
Spruce Budworm ◽  
Interactive Effects ◽  
The Novel ◽  
Forest Stands ◽  
General Guideline ◽  
Number Of Males

Abstract Spruce budworm, Choristoneura fumiferana Clem. (Lepidoptera: Tortricidae), is the most severe defoliator of Pinaceae in Nearctic boreal forests. Three tools widely used to guide large-scale management decisions (year-to-year defoliation maps; density of overwintering second instars [L2]; number of males at pheromone traps) were integrated to derive pheromone-based thresholds corresponding to specific intergenerational transitions in larval densities (L2i → L2i+1), taking into account the novel finding that threshold estimates decline with distance to defoliated forest stands (DIST). Estimates of thresholds were highly variable between years, both numerically and in terms of interactive effects of L2i and DIST, which limit their heuristic value. In the context of early intervention strategy (L2i+1 > 6.5 individuals per branch), however, thresholds fluctuated within relatively narrow intervals across wide ranges of L2i and DIST, and values of 40–200 males per trap may thus be used as general guideline.

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