Progress 09/01/01 to 08/31/04
Outputs
Yellow rocket, Barbarea vulgaris (R. Br.) var. arcuata, was evaluated as a trap crop for diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), in cabbage, Brassica oleracea L. var. capitata, in New York in 2003 and 2004. In 2003, the numbers of P. xylostella larvae found in field plots of cabbage alone were 7.0 times higher than those on cabbage plants in plots that included cabbage and several rows of yellow rocket. In an outdoorexperiment in screenhouses, P. xylostella oviposition on cabbage was compared among six treatments that varied in the percentage of yellow rocket in relation to cabbage (0, 4, 8, 16, 24, and 32 percent of the plants were yellow rocket). Results indicated that the percentage of eggs laid on cabbage decreased as the percentage of yellow rocket in the treatment increased, but this decrease was not significant beyond 20 percent of the plants being yellow rocket. In 2004, the numbers of P. xylostella larvae in field plots of
cabbage alone were 1.8 and 2.0 times Again, these numbers and not in the text higher than numbers in treatments with 10 percent and 20 percent trap crop, respectively. Sticky trap and sweep net captures of P. xylostella adults indicated that within-field dispersal was reduced by the presence of yellow rocket and aggregation occurred around yellow rocket plants. Our studies suggest that using yellow rocket as a trap crop may reduce P. xylostella infestations in cabbage fields and this possibility is discussed in the context of general insect pest management in crucifers.
Impacts
These results indicate the yellow rocket may be a useful trap crop for diamondback moth, but additional work needs to be done to determine how best to deploy this plant in time and space.
Publications
- Badenes-Perez, F., A. M. Shelton and B. A. Nault. 2004. Evaluating trap crops for diamondback moth. J. Econ. Entomol. 97: 1365-1372.
- Lu, J., S. Liu and A. M. Shelton. 2004. Laboratory evaluations of a wild crucifer Barbarea vulgaris as a management tool for the diamondback moth. Bull. Ent. Research 94:509-516.
- Shelton, A. M. and B. A. Nault. 2004. Dead-end trap cropping: a technique to improve management of the diamondback moth. Crop Protection 23: 497-503
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Progress 01/01/03 to 12/31/03
Outputs
Potential trap crops for the diamondback moth, Plutella xylostella (L.) (Lepidoptera: Plutellidae), were evaluated through a series of ovipositional preference and larval survival experiments in outdoor screenhouses in 2002 and 2003. Hosts examined as trap crops were glossy and waxy collards, Brassica oleracea L. var. acephala, Indian mustard, Brassica juncea (L.) Czern, and yellow rocket, Barbarea vulgaris (R. Br.) var. arcuata. More eggs were laid on the potential trap crops than on cabbage, with the exception of waxy collards. When P. xylostella was offered multiple hosts at the same time, numbers of eggs laid on glossy collards, Indian mustard, and yellow rocket were 3, 18, and 12 times greater than on cabbage, respectively. Similarly, when P. xylostella was offered a single trap crop host and cabbage, numbers of eggs laid on glossy collards, Indian mustard, and yellow rocket were 300, 19, and 110 times greater than on cabbage, respectively. Our studies suggest
differences in oviposition between the potential trap crops and cabbage were likely due to host volatiles, or leaf morphology and color, or a combination of these factors, rather than to total leaf areas, leaf shape, or plant architecture. Two-choice tests with a Y-tube olfactomer showed that plant volatiles were major factors in P. xylostella host preference. The percentage larval survival from egg to pupation was 22.2 on cabbage, 18.9 on waxy collards, and 24.4 on Indian mustard, whereas survival was significantly lower on glossy collards (6.7) and yellow rocket (0). No larvae survived until pupation on yellow rocket.
Impacts
These results indicate the yellow rocket may be a useful trap crop for diamondback moth, but additional work needs to be done to determine how best to deploy this plant in time and space.
Publications
- No publications reported this period
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Progress 01/01/02 to 12/31/02
Outputs
Designing a trap-cropping approach to manage diamondback moth (DBM) in cabbage requires identification of a host of the same or different species that is highly preferred over cabbage at the time the DBM is searching for a host. Additionally, the dispersal behavior/colonization pattern of DBM must be known in order to determine the best spatial arrangement of the trap crop in the field. Presently, we have documented through choice tests that DBM prefers to lay eggs on glossy collard plants than on cabbage. We also have found that DBM larval survival on glossy collards tends to be lower than on cabbage. Taken together, these results suggest that glossy collards may be an effective trap crop for DBM in cabbage fields because adults will preferentially lay eggs on the glossy collards than on cabbage, and the glossy collards may be a poor host for larvae. This is advantageous because the glossy collards may not serve as a significant nursery for subsequent DBM generations
that could continually infest the cabbage field. DBM colonization patterns were investigated by monitoring larval populations in small cabbage fields that either contained or did not contain large, glossy collard plants. We found more DBM larvae on cabbage plants near the location where adults were released into the field than on plants at increasing distances away from the release point. We also noted that the relative size of the DBM larval infestation was lower in cabbage fields containing large, glossy collard plants than in plantings of cabbage only. Data on the number of eggs and adults captured at varying distances from the release point have been collected but not yet processed. Results from experiments conducted this summer have helped us better understand the two most important areas (host preference and DBM movement) needed to design a trap cropping strategy for DBM in cabbage. Yet, some of the experiments need to be repeated next summer and future studies are needed to
identify how glossy collards can best be used as a trap crop in commercial fields.
Impacts
This project is in its initial stage.
Publications
- No publications reported this period
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Progress 01/01/01 to 12/31/01
Outputs
Crucifers are attacked by a complex of insects from several different orders but the major pests in the northeast and midwest are Lepidoptera, such as the diamondback moth (DBM), the imported cabbageworm (ICW) and the cabbage looper (CL). The primary tool for management of Lepidoptera has been insecticides and growers typically use a variety of carbamate and organophosphate insecticides and nearly all fields are treated several times. Furthermore, at least one species of Lepidoptera, the DBM, is resistant to many of the available insecticides. An alternative to the use of insecticides is the practice of trap cropping, i.e. planting strips of a highly preferred but economically less important plant within a commercial crucifer field. Barbarea vulgaris (commonly known as Yellow Rocket) appears to be a "dead end" trap crop for the lepidopteran complex in the northern US. Barbarea vulgaris is a common biennial weed found along roadsides, in pastures and in old fields in
the northeast and midwest. In laboratory studies we have documented a nearly 6-fold preference for DBM to lay its eggs on B. vulgaris compared to another common crucifer, but a total lack of survival of DBM larvae on B. vulgaris. Preliminary tests conducted in large field cages in 2001 confirmed these earlier findings, and field studies are planned for 2002.
Impacts
The project is in its initial stages.
Publications
- No publications reported this period
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