Arthropod population and community dynamics in turfgrass

Abstract

Non-target arthropod and nematode populations in ographics. fungal and nematode treated bermudagrass were contrasted with populations in a chlorpyrifos and an untreated control treatment. Fifty-five arthropod families or suborder, herein referred to as species groups, were recorded during a two year period. Staphylinidae, Sminthuridae, lsotomidae, and Oribatida were the four most abundant species groups accounting for 97.0 % of the cumulative density. Three orders and a miscellaneous nematode category were recorded during the same period. Tylenchida was the most abundant nematode species group accounting for 77.2 o/o of the cumulative density. Analyses of variance were conducted for each of the 20 most abundant arthropod species groups with treatment, year, and sample date as factors. The treatment effect was significant for the Lycosidae, miscellaneous Araneae, Oribatida, Staphylinidae, lsotomidae. Fonnicidae, and Scelionidae. Chlorpyrifos significantly reduced the population densities of Lycosidae, miscellaneous Araneae, Staphylinidae, Isotomidae, Formicidae, and Scelionidae compared with the untreated control. A second analysis of variance was conducted for the arthropod data with inhabitance category-tropic level as an additional factor. Treatment had a significant effect on the abundance of all the inhabitance-trophic levels, except the plant-inhabiting herbivores. The impact of seven fungal and nematode treatments, a chlorpyrifos treatment, and an untreated control on the association between non-target arthropod and nematode populations in bermudagrass was evaluated. The number of significant pairwise correlations between arthropod species groups was highest (40 = 21. 1%) in the S. bassiana treatment while the chlorpyrifos treatment had the lowest number of significant arthropod correlations (25 = 13.2%), contrasted with the untreated control (33 = 17.4%). ABSTRACT highest number of significant conelations (47 = 28.6%), while the Gryllidae had the lowest number (7 = 4. 1%). Neither the mean density of each arthropod species groups nor treatment as a factor significantly affected the number of significant pairwise correlation. A cluster analysis of the arthropod and nematode pairwise correlation coefficients indicated that the similarity across the treatments was the highest in the HL bacteriaphora and S. riobravis treatments, followed by the f-'. bacteriaphora + #. bassiana and S. carpocapsae + .8. bassiana, then followed by the S. riobravis + B. bassiana treatment and the untreated control.