LISA McNICOL FOREHAND. Evaluation of Commercial Beneficial Insect Habitat Seed Mixtures for Organic Insect Pest Management (Under the direction of David B. Orr and H. M. Linker).

       A laboratory study conducted in 2003 evaluated the purity, composition and germination of three commercial mixes: Border Patrol™ (BP), Beneficial Insect Mix (BIM), and Good Bug Blend (GBB). Regarding seed purity, BP had two weed species present and live beetles (Coleoptera: Bostrichidae) were present and actively feeding on seeds, BIM had one weed species present and one advertised species missing and GBB had fourteen different weed species present and three advertised species missing. The composition of BP found buckwheat and nasturtium to be the largest proportion by weight, while yarrow and evening primrose had the greatest seed numerical abundance. In BIM, the largest proportion of seeds by weight were coriander and candytuft, but numerically candytuft and Siberian wallflower were most abundant. The majority of seeds in GBB by both weight and numerical abundance, were clovers and alfalfa. Germination of seeds in BP was variable with two species having 0% germination, most likely due to seed feeding and pathogen growth from insect frass. BIM demonstrated good overall germination, with the exception of gayfeather. All seeds in GBB, except fennel, germinated at or above test values provided by the supplier.

        A field study was conducted in 2003 to evaluate three commonly grown flowers (Zinnia, Celosia and fennel) and three commercially available beneficial insect habitat seed blends (Peaceful Valley’s Good Bug Blend, (GBB) Clyde Robin’s Border Patrol™ (BP) and Heirloom Seed’s Beneficial Insect Mix (BIM)) to determine what insects were present in each of these different plant communities. Three experiments were conducted to evaluate mixes: 1) insect samples were collected using a D-vac, identified to family and evaluated by feeding guilds; 2) pitfall traps were collected to monitor ground beetle and ground-dwelling spider populations; and 3) dusk observations recorded visits by noctuid and hornworm moths. Celosia offered the largest diversity and abundance of predators and parasitoids in the flower plots, although the specimens collected were not found to be significant in the control of agronomic pests. Fennel, although not flowering until late summer, had the lowest overall abundance and diversity of all flowering blocks. The BP plantings had the highest diversity and abundance of herbivore crop pests as well as the highest instances of Lepidoptera pests during night observations. GBB had the highest abundance and diversity of beneficial parasitoids and predators.

        A field study was conducted in 2003 and 2004 to evaluate the effectiveness of a commercially available beneficial insect habitat (BIH) in decreasing pest caterpillar populations. Six pairs of organically managed tomato plots were established and Peaceful Valley’s Good Bug Blend transplanted around the perimeter of treatment plots, while a brown-top millet border was planted around the controls. Helicoverpa zea and Manduca spp. eggs were monitored and categorized based on the fate of each egg after one week. When analyzed for the effect from year, treatment, year by treatment, date within year and treatment by date within year, the only significant difference seen was in parasitism by date within year. Plots were scouted weekly and the fates of hornworm larvae (Manduca spp.) were evaluated to determine if the beneficial insect habitat had an effect on larval parasitism by the braconid wasp Cotesia congregata. There was no significant difference when data were analyzed for the effect from year, treatment, year by treatment and treatment by date within year for either 2003 or 2004. However, a significant difference was seen when evaluating date within year for larval populations. This study indicates that natural enemy populations were not amplified by the presence of a commercially available BIH.

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