A study of the fine structure and the function of the ocellus of the adult cabbage looper (Trichoplusia ni, Hübner) (lepidoptera: noctuidae)

The structure of the cabbage looper ocellus was examined by light and electron microscopy. Rhabdoms were found in the distal region of the retinula cells. These were formed by the apposition of microvillar borders of adjacent cells, thus, an interrupted network of rhabdoms was found to exist in cross section. No convergence of first order neurons to second order neurons was found anywhere above the protocerebrum as is typical of insect photoreceptors in general. No synapses were found to exist anywhere above the brain. It is hypothesized that the cabbage looper ocellus plays a major role in determining the light intensity at which crepuscular flight is initiated. This hypothesis was tested in the following manner. Laboratory reared moths were divided into five groups each with a different or no treatment. These were: 1. Compound eyes and ocelli occluded. 2. Compound eyes occluded. 3. Ocelli occluded. 4. Controls. 5. Controls sham treated. All groups were placed in transparent flight chambers and submitted to a simulated sunset. Test results were compared using the Duncan Multi-Range Test and Standard errors. The results indicate that the cabbage looper ocellus plays a role in determining the light intensity at which crepuscular flight is initiated.

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

1975

Author dc:creator

• Dow, Matthew Allen

Chair dc:contributor.committeechair

• Eaton, John L.

Committee members dc:contributor.committeemember

• Grayson, James McD.
• Turner, E. Craig Jr.
• Pienkowski, Robert L.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

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

Dc Identifier Other

etd-06082010-020231

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/42933