Subterranean termites encounter numerous kinds of fungi during foraging and feeding
activities. Nearly nine decades of research have exposed only a small fraction of the termitefungal
interactions that exist in nature. The first portion of research presented here focused on
how feeding behaviors of Reticulitermes virginicus (Banks) were affected by the fungus
Trichoderma virens (Miller, Giddens & Foster) von Arx. Tests were performed with 'P' (GLT+)
and 'Q'(GLT-) strains of T. virens. Both strains were applied to filter paper and wood disks cut
from southern yellow pine and Sentriconî monitoring devices. The first bioassay assessed the
termites' feeding responses to fungal extracts removed from liquid media on days 2 through 7,
and again on day 15. Only the GLT+ extracts from days 6 and 7 inhibited termite feeding
significantly from the controls (16% and 54% less area loss, respectively). Response to wood
covered by live T. virens mycelia was tested in the second bioassay. No significant differences
in termite consumption were seen between fungal strains, but both substantially reduced the area
loss due to termite feeding of treated wood by an average of 35%. A vacuum impregnation
system was used to inoculate wood disks with fungal homogenate in the third bioassay. The
wood treated with either GLT+ or GLT- homogenates did not have significant differences in area loss due to termite feeding. Overall, these results reiterated the plasticity that exists with termitefungal
relationships.
The second research topic addressed the applicability of labrum-based identification
techniques to Reticulitermes Holmgren in Texas. Soldier labral morphology of four species, R.
flavipes (Kollar), R. hageni (Banks), R. tibialis Banks, and R. virginicus (Banks), was evaluated
as a character to separate species. Length and width measurements of five soldier labra were
taken from each of the eight collection sites. These results were then judged against molecular
analysis of the mtDNA 16S rRNA gene. Findings showed that labral shape was an unreliable
diagnostic characteristic when comparing all species. A combination of length and length-towidth
ratio successfully segregated all four Reticulitermes species. Comparison of a
morphology-based dendogram to the phylogenetic analysis revealed a shared pattern between
phenotypic and genotypic variations.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/5963 |
| Date | 17 September 2007 |
| Creators | Heintschel, Bryan P. |
| Contributors | Gold, Roger E. |
| Publisher | Texas A&M University |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Thesis, text |
| Format | 6272465 bytes, electronic, application/pdf, born digital |
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