scholarly journals Seasonal occurrence of three Lepidoptera on broccoli and effectiveness of planting date as a pest management tool in southeastern New Brunswick

2005 ◽  
Vol 79 (3) ◽  
pp. 129-137 ◽  
Author(s):  
P.M. Maltais ◽  
J.R. Nuckkle ◽  
P.V. LeBlanc

Seasonal variations in abundance of three lepidopterous pests, the diamondback moth, Plutella xylostella [Lepidoptera : Plutellidae], the imported cabbageworm, Pieris rapae [Lepidoptera : Pieridae], and the cabbage looper, Trichoplusia ni [Lepidoptera : Noctuidae], were monitored over two years in broccoli plantings (Brassica oleracea var. italica) in southeastern New Brunswick. Four population peaks of imported cabbageworm were seen in 1990 and 1991 with 92 and 99% of the total larval population, respectively, being recorded during the latter part of the season, after 23 July. Four population peaks were also recorded for the diamondback moth in 1990 and 1991 with 81 and 97%, respectively, of the population being recorded after 23 July. Populations of cabbage looper appeared later in the season and because of low numbers were more difficult to assess. Using cabbage looper equivalents (CLE), the effectiveness of planting date as a pest management tool was also studied. Early crops have lower mean CLE per plant

1997 ◽  
Vol 32 (2) ◽  
pp. 120-137 ◽  
Author(s):  
E. R. Mitchell ◽  
G. Y. Hu ◽  
J. Okine ◽  
J. R. McLaughlin

Experiments were conducted in commercial plantings of cabbage in spring 1994 and 1995 to evaluate the efficacy of a blend of pheromones for diamondback moth, Plutella xylostella (Linnaeus), and cabbage looper, Trichoplusia ni (Hübner), for disrupting mating when dispensed simultaneously from Yoto-con-S® ‘rope’ dispensers (Shin-Etsu Chemical Co., Ltd., Tokyo, Japan). A 12.1-ha cabbage field was treated with pheromone in 1994 using a blend of (Z)-11-hexadecenal, (Z)-11-hexadecen-l-ol acetate, and (Z)-11-hexadecanol in a 49:50:1 ratio for diamondback moth and (Z)-7-dodecen-l-ol acetate and (Z)-7-dodecen-l-ol in a 98:2 ratio for cabbage looper. The test was repeated in 1995 using a 10.1-ha cabbage field. In 1995, 24.6 ha of cabbage also were treated with a blend of diamondback moth-only pheromone: (Z)-11-hexadecenal and (Z)-11-hexadecen-l-ol acetate in a 50:50 ratio. All pheromone treatments were applied at the rate of 1,000 m rope per ha within 2 wk after the cabbage was planted. Captures of diamondback moth and cabbage looper males in traps baited with synthetic pheromones and mating by laboratory-reared sentinel females in pheromone-treated fields were significantly reduced for 7 to 9 wk post-treatment relative to control areas. Larval infestation data on cabbage were insufficient to establish the effect, if any, of the diamondback moth/cabbage looper combination pheromone treatment on cabbage looper control. In 1995, the diamondback moth pheromone only and the diamondback moth/cabbage looper combination pheromone effectively suppressed diamondback moth larval numbers below the composite economic action threshold of 0.3 larva per cabbage plant for approximately 60 days. A single application of pesticide quickly reduced the diamondback moth larval count below the action threshold in the pheromone-treated cabbage, and no further pesticide applications were required. The correspondent control field was sprayed 7 times with pesticides for control of diamondback moth.


1955 ◽  
Vol 87 (9) ◽  
pp. 400-406 ◽  
Author(s):  
D. G. Harcourt ◽  
R. H. Backs ◽  
L. M. Cass

Cabbage and related crops are attacked every year throughout Ontario by caterpillars of three species, namely, the imported cabbageworm, Pieris rapae (L.), the diamondback moth, Plutella maculipennis (Curt.), and the cabbage looper, Trichoplusia ni (Hbn.). The imported cabbageworm is generally regarded as the most abundant of the three species and is reported as doing damage of considerable economic importance each year. The cabbage looper does not occur in large numbers until late in the season, but in most years it is believed to be second only in importance to the imported cabbageworm. The diamondback moth is generally considered to be much less important than the other two species (Caesar, 19i8). As previously reported (Matthewman et al., 1952), these beliefs were not borne our by observations of field populations at Ottawa in 1950. Whereas populations of the cabbage looper were strikingly low, those of the diamondback moth were much higher than the literature indicated. This paper is a summary of four seasons' experiments, 1951-1954, undertaken to assess the abundance and relative importance of the three species in eastern Ontario.


1973 ◽  
Vol 105 (1) ◽  
pp. 21-27 ◽  
Author(s):  
R. P. Jaques

AbstractThe control of larvae of the cabbage looper, Trichoplusia ni, and the imported cabbageworm, Pieris rapae, by viruses, bacteria, and chemical insecticides was compared. In small field plots five applications of the nuclear-polyhedrosis virus of T. ni (1.8 × 1011 polyhedra/acre) and the granulosis virus of P. rapae (4 ×1011 granules/acre) controlled the respective host larvae as well as five applications of the chemical insecticide methomyl (0.5 to 1 lb/acre). Dipel HD-1 (0.25 lb/acre) and Thuricide HPC (60 fl. oz/acre), formulations of Bacillus thuringiensis, were as effective against T. ni larvae as methomyl but not as effective as Fundal (0.5 lb/acre) or Dipel at a higher rate (0.5 lb/acre). The control obtained by combinations of viruses with endosulfan or methomyl suggested an effective method of reducing use of chemical insecticides. Control of T. ni and P. rapae in plots up to 3 acres in area in growers’ fields demonstrated the effectiveness of the viruses when used as commercial insecticides.


1994 ◽  
Vol 126 (2) ◽  
pp. 379-387 ◽  
Author(s):  
Andrew P. Dornan ◽  
Jeff G. Stewart ◽  
Mark K. Sears

AbstractAction thresholds for imported cabbageworm, Pieris rapae (L.), diamondback moth, Plutella xylostella (L.), and cabbage looper, Trichoplusia ni (Hübner), were evaluated on two cultivars of cabbage, Brassica oleracea var. capitata (L.), in Prince Edward Island. Thresholds were tested on plots of mid-season cabbage, cv. Minicole, and late-season cabbage, cv. Lennox, both grown for fresh market in 1991 and 1992. Management of larval populations at a threshold of 0.25 Cabbage Looper Equivalents (CLE) per plant resulted in yields equal to those obtained with bi-weekly applications or grower treatments. Higher thresholds of 0.50 and 1.0 CLE per plant were not as useful and did’ not consistently result in yields greater than untreated plots. Use of the threshold of 0.25 CLE per plant reduced the number of applications of insecticides by 30% compared with spraying insecticide at bi-weekly intervals from heading to harvest, and 43% compared with management by the grower without regard to insect populations or growth stage of the crop.


1994 ◽  
Vol 126 (4) ◽  
pp. 961-969 ◽  
Author(s):  
Andrew P. Dornan ◽  
Jeff G. Stewart ◽  
Mark K. Sears

AbstractAn investigation into the use of thresholds based on Cabbage Looper Equivalents (CLE) was conducted on Brussels sprouts, Brassica oleracea var. gemmifera (L.), cv. Valiant, grown in Prince Edward Island in 1991 and 1992. The CLE model was used to equate foliage consumption by larvae of the imported cabbageworm, Pieris rapae (L.), the diamondback moth, Plutella xylostella (L.), and the cabbage looper, Trichoplusia ni (Hübner). Management strategies included the following: (1) an untreated check; applications of insecticides after thresholds of (2) 1.0 CLE; (3) 0.50 CLE; or (4) 0.25 CLE per plant were exceeded; (5) bi-weekly applications of insecticides; and (6) applications of insecticides according to the grower’s spray schedule.In 1991, the imported cabbageworm was the most abundant species in the complex attacking the crop and high yields were obtained in all treatments. However, in 1992, the diamondback moth was the principal species and significantly reduced marketable yields in all treatments. Use of CLE as a model for threshold determination in the crop of Brussels sprouts underestimated the potential of the diamondback moth for damage and resulted in improper timing of applications of insecticide for adequate control of the diamondback moth.


1983 ◽  
Vol 115 (11) ◽  
pp. 1529-1531 ◽  
Author(s):  
M. A. Latheef ◽  
J. H. Ortiz

Public participation in home vegetable gardening and small farm operations is increasing in North America. This is expected to intensify the use of insecticides and disproportionately increase public exposure to them. For instance, von Rurnker et al. (1972) estimated that on an area basis homeowners in the midwestern United States applied ca. 5.0 lb of pesticides per acre. This amount when compared with 1½ to 3 lb per acre applied by the farmer suggests that backyard gardens receive a heavier pesticide application than most other land areas in the United States. It is, therefore, important to develop ecologically less aggressive control methods for small farm operations.


1952 ◽  
Vol 84 (11) ◽  
pp. 346-352 ◽  
Author(s):  
W. G. Matthewman ◽  
D. G. Harcourt ◽  
J. P. Perron

Three species of caterpillars commonly attack cabbage at Ottawa, namely, the imported cabbageworm, Pieris rapae (L.), the larva of the diamondback moth, Plutella maculipennis (Curt.) and the cabbage looper, Trichoplusia ni (Hbn.). All three species are readily controlled with DDT sprays or dusts but the timing of the applications is imporrant. Growers sometimes begin dusting or spraying too early, wasting one or more applications, or they delay the first application until mid-August, when severe damage has already occurred. This paper is a report on four seasons' experiments at Ottawa, 1947 to 1950, to determine the number and timing of applications of DDT required for control of caterpillars on late cabbage.


2005 ◽  
Vol 40 (2) ◽  
pp. 211-221 ◽  
Author(s):  
Suzanne J. Wold-Burkness ◽  
W. D. Hutchison ◽  
Jana C. Lee ◽  
R. L. Hines ◽  
P. C. Bolin ◽  
...  

Field studies were conducted near Rosemount, MN, during the years 1991–1994, 1996–1997, and 1999–2003, to assess the diversity of and parasitism by larval and pupal parasitoids of cabbage looper, Trichoplusia ni (Hübner), imported cabbageworm, Pieris rapae (L.), and diamondback moth, Plutella xylostella (L.). Species composition, parasitism rate, and species abundance (Hill's N1) were determined for each pest species. Voria ruralis (Fallen), Copidosoma floridanum (Ashmead), and Compsilura concinnata (Meigen) were the dominant parasitoids of T. ni; Phryxe pecosensis (Townsend), Cotesia glomerata (L.), and Pteromalus puparum (L.) are the dominant parasitoids of P. rapae; and Diadegma insulare (Cresson) is the dominant parasitoid of P. xylostella. In addition, the first records of the introduced parasitoid, C. concinnata, parasitizing T. ni and P. rapae, and Cotesia rubecula (Marshall) parasitizing P. rapae are documented for Minnesota.


1960 ◽  
Vol 92 (6) ◽  
pp. 419-428 ◽  
Author(s):  
D. G. Harcourt

The diamondback moth, Plutella maculipennis (Curt.), is a sporadic pest of cruciferous crops throughout Canada. It is normally held in check by a multiplicity of environmental factors, chiefly biotic; however, serious outbreaks do occur (MacNay, 1948, 1953, 1957, 1959). In eastern Ontario it has been extremely numerous since late 1951, and during the present study, 1952 – 1956, it was more abundant than the imported cabbageworm, Pieris rapae (L.), or the cabbage looper, Trichoplusia ni (Hbn.) . Two earlier papers (Harcourt, 1956, 1957) presented the history, distribution, and synonymy of the insect, giving general descriptions of the stages and many aspects of its biology in eastern Ontario. This article gives the relative abundance of its parasites and predators, and discusses certain population relationships.


2001 ◽  
Vol 36 (3) ◽  
pp. 297-304 ◽  
Author(s):  
G. Y. Hu ◽  
E. R. Mitchell

A flight tunnel bioassay was used to evaluate attraction responses of female Diadegma insulare (Cresson), a host-specific parasitoid of the diamondback moth, Plutella xylostella (L.), to collard plants (Brassica oleracea var. acephala L.) infested with host and nonhost caterpillars. Adult female wasps showed increased responses to odors of the plant-host complex after a brief contact experience with host-infested collard leaves. Such an increase shows evidence of associative learning in this parasitoid to the odor released from the larval-plant complex. The same experimental design was also used to determine responses of the parasitoid to plants infested with nonhost larvae-cabbage looper, Trichoplusia ni (Hübner), and imported cabbageworm, Pieris rapae (L.). The female wasps conditioned to the plants infested with host larvae also showed increased responses to plants infested with larvae of cabbage looper or imported cabbageworm. These results indicate that plants damaged by host and nonhost caterpillars may release general odors that are attractive to D. insulare. The general damage odors caused by host and nonhost larval feeding may enhance biological control of the diamondback moth. Host-search ability of the parasitoid increases after experiencing host damage. When host populations are low in fields, plant odors caused by generalist herbivore feeding may also attract D. insulare parasitoids to the vicinity, thereby improving encounter chances of the parasitoid encountering diamondback moth larvae.


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