|Johanowicz, Denise - DEPT OF ENT, UNIV OF FL|
Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 29, 1999
Publication Date: March 1, 2000
Interpretive Summary: The diamondback moth and cabbage looper are among the most important insect pest of cruciferous crops (cabbage, broccoli, and mustard) worldwide. They cost growers an estimated $1 billion annually in pest control costs and crop losses. Growers traditionally have relied on pesticides to manage these pests. To help reduce problems caused by applying chemical pesticides, such as pesticide resistance, environmental pollution, and increased cost, scientists at the Center for Medical, Agricultural, and Veterinary Entomology at Gainesville, Florida are developing an integrated pest management program for these pests in Florida cabbage. Components of the program include the use of pheromones to disrupt mating, release of natural enemies, planting of trap crops, and application of natural insecticides such as Bt. Two native parasitic wasps, Diadegma insulare and Cotesia marginiventris, are reared in the laboratory and released into cabbage fields earlier than they naturally appear so that they will be available when pest numbers start to build up. Since parasitic wasps need a carbohydrate (sugar) source for longevity, planting flowering plants with accessible and appropriate nectar in and around cabbage fields may help retain and maintain released parasites so that they can control pest populations for a longer period of time. Sweet alyssum is an annual which flowers in the winter, and may survive in cabbage fields since both plants grow best in the cooler months. When caged with flowering sweet alyssum, both of these parasite species lived much longer than when provided with water alone. Sweet alyssum could be a useful companion plant in the cabbage agroecosystem to help maximize the effectiveness of biological control agents.
Technical Abstract: The effects of sweet alyssum (Lobularia maritima) (Brassicaceae) flowers on the longevity of two augmentatively-released parasitoids, Cotesia marginiventris (Cresson) (Hymenoptera: Braconidae) and Diadegma insulare (Cresson) (Hymenoptera: Ichneumonidae), were studied in a greenhouse experiment. C. marginiventris and D. insulare survived approximately 4.8 and 12.7 times longer, respectively, when provisioned with honey or with sweet alyssum than with water alone. Sweet alyssum planted in northern Florida cabbage fields may be one way to improve biological control by augmentatively-released natural enemies of lepidopteran pests by increasing adult parasitoid longevity during times when few wild plants are in bloom.