Kirra Kent | ALES Graduate Seminar

Event details: A graduate exam seminar is a presentation of the student’s final research project for their degree.
This is an ALES MSc Final Exam Seminar by Kirra Kent. This seminar is open to the general public to attend.

MSc with Drs. Boyd Mori and Jaime Pinzon

Thesis Topic: Assessing spider (Araneae) diversity and pitfall trap retention in canola (Brassica napus L.) agroecosystems in north-central Alberta, Canada

Abstract:

Little is understood about the role of spiders (Araneae), their community composition, and predator-prey interactions in canola agroecosystems. Understanding these relationships may inform management decisions to effectively use spiders as biological control agents against insect pests. In 2021-22, a study was conducted to assess spider diversity in canola (Brassica napus L.) fields in the aspen parkland region of Alberta. The initial sampling regime installed traps on the edge and within the field interior, with few spiders captured. To overcome this, additional experiments tested modified pitfall trap designs, to improve the retention rates of all spiders. Modified trap designs consisted of a combination of three factors: trap size, presence/absence of polytetrafluoroethylene (PTFE), and presence/absence of preservative fluid (propylene glycol). PTFE is a substance used for creating non-stick surfaces, which causes spider silk to fail to adhere effectively. Traps with and without preservative were included to test if PTFE could improve the retention of live spiders. Beads were used as they provided hiding spaces without damaging the traps inner walls. Beads were only employed in the 24-hour sampling periods, all 7-day sampling periods employed only preservative filled traps, which were treated or untreated with PTFE. Traps were installed in two habitat types, herbaceous edges, and woody tree edges. Across all years of this study, the spider community in canola was dominated by two species in the family Lycosidae: Pardosa distincta (Blackwall) and Pardosa moesta Banks. Trap diameter, PTFE application and preservation method impacted the abundance, diversity and richness of spiders collected. Large trap sizes treated with PTFE increased the abundance, diversity and richness of spiders captured, but only in tree-edge habitat. Taken collectively, this research will further our understanding of the role of abundant spider species in the aspen parkland-canola agroecosystem and offer a novel technique for improving the passive-live collection of spiders.