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Continued Studies of Insect Population Dynamics in Crimson Clover and Refugia/Cotton Systems. Part II: Pitfall Trap Sampling

Philip B. Haney, W. Joe Lewis, Sharad Phatak


 
ABSTRACT

Linear and transect pitfall traps were used to monitor and compare the seasonal abundance of epigeal (ground-dwelling) arthropods in three cotton fields in Dooly and Tift county, in the Coastal Plain region of south Georgia. In Dooly county linear pitfall traps were placed in a 20 ha conservation-tilled (Crimson clover) field and in a nearby 20 ha conventional-tilled (fallow) field. In Tift county linear pitfall traps were also placed in a 10 ha conventional-tilled field interspersed with six permanent 3-row refugia strips comprised of Crimson clover and annual weeds. Pitfall traps were also placed in two transects across the Tift county field. Arthropod taxa commonly captured at all three study sites included two species of Collembola, Bourletiella hortensis (Sminthuridae) and Podura aquatica (Poduridae), the striped earwig Labidura riparia, fire ants, Solenopsis invicta, twenty Carabid species and seven Staphylinid species. Other abundant epigeal arthropods included Wolf spiders (Pardosa) and Thomisids, and one species of centipede, nr. Lithobius forficatus. The Anthicid (ant-like beetle), Notoxus monodon, two Cicindelids (tiger beetles), Megacephala carolina and Cicindela nr. sexguttata, and one unidentified Pedilid were also captured, but at low levels.

In Dooly county, 1994-95 seasonal densities of Collembola and L. riparia in the conventional-tilled clover field were significantly higher than densities in the conservation-tilled fallow field. Densities of spiders and centipedes were significantly higher in the clover field. Wolf spiders (genus Pardosa), and Thomisids were the predominant spider species collected in the traps. S. invicta and Carabid densities were numerically, but not significantly, higher in the clover field. Staphylinid densities were not significantly different.

In Tift county, seasonal densities of Collembola and L. riparia captured in the linear traps were also significantly higher in the conventional-tilled cotton strips. S. invicta, Carabid, spider and centipede densities were all significantly higher in the refugia strips. Staphylinid densities were not significantly different. Densities of spiders and Carabid beetles captured in the transect traps were significantly higher in the cotton strips lying between or immediately adjacent to the refugia strips. The overall density and distribution of epigeal beneficials in the Tift county field, even within the cotton strips most distant from the refugia strips, remained high throughout the 1995 season.



Reprinted from Proceedings of the 1996 Beltwide Cotton Conferences pp. 1115 - 1119
©National Cotton Council, Memphis TN

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Document last modified Sunday, Dec 6 1998