Sample information

Our group found this small spider near a stone tile on the edge of a school garden in the spring on a sunny day near school. We collected it in the morning, 9AM, at around 70 degrees F outside. We attached a picture of the area we collected the pillbug from above, and there did not appear to be additional spiders of its kind in the area.

Methods

DNA Extraction

The spider was too small to precisely isolate and separate the abdomen DNA extraction, so the entire specimen was crushed up thoroughly for our sample DNA extraction.

Gel Electrophoresis

The following lane order for our gel:

1. N/A
2. N/A
3. Steatoda triangulosa (3-1; small spider)
4. N/A
5. N/A
6. Steatoda grossa (3-2; big spider)
7. N/A
8. Armadillidum vulgare (3-2; isopod)
9. N/A
10. Wolbachia positive sample (3-4)
11. Wolbachia negative sample (3-5)
12. DNA positive sample (3-6)
13. Ladder
14. DI Water

Data Analysis

We had problems with our positive and negative Wolbachia controls, namely we had to rush part of the process for running our samples due to time constraints. The small spider sample well displayed one single visible band, a different quantity and position as the two visible bands from the positive Wolbachia DNA control. The putative identification for this small spider specimen was revealed to be Mermessus fradeorum, not Steatoda triangulosa. The assumption for the latter considered frequently-appearing native spider species to Southern California, but while the specimen we assessed has no recorded sightings in California, it is still frequently sighted in North America and is extremely small relative to other spiders, making visual detection difficult. This species is confirmed to be infected by Wolbachia for the most part.

Results

While the DNA positive sample and ladder went well, the Wolbachia positive and negative samples showed no bands. This is likely a mishap during Wolbachia sample extraction, and keeps us from fully confirming the precision of our samples. Despite this, at least one band should have appeared on both Wolbachia samples, and the single band in our small spider sample (Mermessus fradeorum) indicates that the sample was successfully extracted, but may not contain Wolbachia DNA exactly as the electrophoresis band distance results indicate unequal band sizes between the Mermessus fradeorum sample and the positive Wolbachia DNA control. Furthermore, we did not run into problems with the small spider DNA extraction in the process, and so we can be relatively confident that the small spider (Mermessus fradeorum) was not infected with Wolbachia. While the species is known to be frequently infected by Wolbachia, it could be possible this particular individual sample was not infected, and we have minimal method to precisely confirm either result.