Spiders associated with apple trees in Virginia with notes on their importance in controlling orchard insect pests

The species complex and population dynamics of spiders were studied in an abandoned and several commercial apple orchards in Virginia. There were 68 and 45 species found in the abandoned and combined commercial orchards respectively. Species numbers in individual commercial orchards ranged from 18-28. There were 16 species common to all sprayed orchards. Members of the Salticidae, Philodromidae, Thomisidae, Theridiidae, Anyphaenidae, and Dictynidae, together comprised about 90% of the total spiders collected in the abandoned orchard during a one year study. Results from commercial orchards reflected similar findings. Two peaks of spider abundance were usually observed in all orchards; a small one in the spring and a larger one in the late summer-fall. Spiders often represented over 50% of the total predators collected in commercial orchards during the spring and fall. Studies of the association of spiders and various pest-prey indicate that spiders may be important suppressive or regulatory agents especially with regards to aphid and tortricid leafroller populations. Results of an evaluation of the seasonal efficiency of the limb beating sampling technique indicated that the sampling method was acceptable for quantitative spider population estimates. The time of sampling did not effect the population estimates of spiders during the normal sampling periods of 6 a.m. - 6 p.m. Spider feeding tests on insect pests-prey and beneficials showed that one pest species could be preyed upon by a complex of spider species. Beneficial insects such as Lepthothrips mali (Fitch) also were susceptible to capture by several spider species.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Entomology

Department dc:contributor.department

Entomology

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1978

Author dc:creator

• McCaffrey, Joseph P.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-10302008-120717

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/45329