Phytoseiidae (Acari: Mesostigmata) from cover crops in western North Carolina

Six cover crop species that might be candidates for establishment in Fraser fir (Abies fraseri) plantations were sampled for Phytoseiidae: Poa pratensis, Festuca arundinacea, Muhlenbergia schreberi, Dactylis glomerata, Trifolium subterraneum and Rumex acetosella. For comparison, Phytoseiidae were also surveyed from a multiple-species feral ground cover in a Fraser fir plantation. The cover crops had been established for a separate study. Sixty 20 m2 plots in a randomized complete block design with 5 blocks of 12 ground cover treatments were laid out at the North Carolina State University (NCSU) Mountain Horticultural Research Station, Fletcher (F), Henderson, North Carolina (NC), USA. The 6 cover crop species were sampled on 18 October 1982, 17 April, 21 June, 20 July, 3 and 16 August, and 6 and 17 September 1983. The feral ground cover was located on an experimental Fraser fir plantation at the NCSU Mountain Research Station, Waynesville (W), Haywood County, NC. This untended ground cover consisted of Aster curtisii [Symphyotrichum retroflexum], P. pratensis, Trifolium repens, T. pratense, F. arundinacea, Stellaria pubera, M. schreberi, Dactylis glomerata, Carduus lanceolatus, Veronica persica and wild Daucus carota and several less common species. In 1982, four samples were taken on 4, 11, 18 and 25 September for a total of 17 sample dates. In 1983, at each sample date, a Fraser fir tree was randomly selected and 5 samples were taken, 3 from under the canopy of the tree and 2 from the cover crop in an adjacent alley. Arthropods collected from the cover crop plots at F included Acari (Mesostigmata, Prostigmata and Oribatida), Chilopoda, Collembola, Diptera (larvae), Homoptera and Thysanoptera. Mesostigmata included the families Ascidae, Parasitidae and Rhodacaridae; Scutacaridae was the predominant family of Prostigmata. Trifolium subterraneum growth was meager and much bare ground occurred in its blocks. Consequently, few arthropods were collected from this crop. At W, the mesofauna from the feral ground cover was similar to that in the cover crop plots at F. Protura was found in the fir needle litter at W. Nine phytoseiid species in 4 genera were collected in the cover crops at F. The predominant species were Proprioseiopsis asetus, P. clausae and Neoseiulus setulus. Fifteen phytoseiid species in 8 genera were collected from the feral ground cover in the Fraser fir plantation at W, including 2 new species (Proprioseiopsis sp. and Typhlodromips sp.). The most abundant species were Neoseiulus cucumeris, N. fallacis and Typhlodromips sessor [Amblyseius sessor]. Phytoseiid diversity and abundance appeared to be similar among the 6 cover crops at F. Although the feral ground cover at W was sampled more intensely and for a longer period of time, it had fewer total specimens than the crops at F. However, it had a greater species diversity than the individual crops at F, both individually and collectively. For the W collections, there was little difference between the number of specimens collected from samples taken from under the canopy of the Fraser fir trees and those samples collected between the tree rows (49% vs 51% of total specimens, respectively).