Seasonal abundance and host preference of Culicoides in Virginia: with emphasis on the ecology of Culicoides variipennis (Diptera: Ceratopogonidae)

Trap type, time and site influenced the species composition, number collected and female age. Thirty species were collected in the BLTs and 17 in the bait traps. Culicoides biguattatus, C. obsoletus, C. stellifer, C. varipennis, and C. venustus were the most abundant species collected in both traps. Eight new host records were reported in this study. The drop trap collected more midges than did the vacuum trap, and the cattle trap collected more midges than did the sheep trap. Culicoides stellifer began host-seeking activity at SS-30 in bait traps and continued to be collected in the blacklight trap the remainder of the night. Earlier in the evening, nulliparous females were collected in higher percentages than parous females. Time of flight for C. stellifer was delayed when the temperature was above 25°C. Culicoides biguttatus and C. variipennis peaked at SS+30 in the bait traps but continued to be collected in the BLTs after dark. C. venustus peaked in the bait traps at SS + 60 and continued to be collected in the BLTs after dark. The parous rate of C. variipennis was higher in the cow trap than the sheep trap at the CP site. This was also true for C. stellifer at the PP site. A morphometric study of C. variipennis indicated that in Virginia using the present taxonomic characters that only one species is present. Culicoides variipennis males swarmed 15-20 minutes before sunset and 99% of the females that entered the swarm were nulliparous. One mating pair dropped the ground every 10 sec and remain in copula from 30-120 sec. The time spend on the the ground by mating pairs significantly increased successful insemination (p<0.01). Dispersal of C. variipennis was at least 0.89 Km. More midges were collected at 1.83 m and 3.05 m than at 0.61and midges collected increased. C. variipennis was collected at least as high as 9.15m and vertical movement occurred away from the breeding site. There was a positive correlation between numbers collected at different sites. Comparison tests showed that the sticky traps, D-Vac, and the bait traps collected similar percentages of parous individuals. The Marsh BLT collected a higher percentage of parous females than did the above sampling methods. Midge parous rates from the Marsh BLT were also higher than the parous rates from the Totten or Allison BLTs. Gravid females were collected in higher percentages in the Marsh BLT (50%) than on the sticky traps (2%) or in the D-Vac (22%). Though the Marsh BLT was biased for parous and gravid females, other data indicated that nulliparous females moved away from the breeding site.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Entomology

Department dc:contributor.department

Entomology

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1981

Author dc:creator

• Zimmerman, Robert Henry

Statement dc:rights

• In Copyright

Licence dc:rights.uri

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

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/74211

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/74211