Title

Effects of Roundup on Behavior, Growth, and Survival of Larval Blue Dashers, Pachydiplax longipennis

Presenter Information

Kayleen ParkerFollow

Academic Level at Time of Presentation

Graduate

Major

Biology

List all Project Mentors & Advisor(s)

Dr. Claire Fuller

Presentation Format

Oral Presentation

Abstract/Description

Effects of Roundup on Behavior, Growth, and Survival of Larval Blue Dashers, Pachydiplax longipennis. KAYLEEN K. PARKER and CLAIRE FULLER, Biology Department, Murray State University, Murray, KY 42071.

The objective of this study was to determine if Roundup (active ingredient: Glyphosate) causes negative effects on behavior, growth, and mortality of larval Pachydiplax longipennis. Larvae were captured from rainwater-filled mesocosms at Hancock Biological Station in Murray, KY. Larvae were exposed to one of four concentrations of Roundup (0mg/L, 2.5mg/L, 5mg/L, or 10mg/L). Daphnia consumption, cover, and poke trials were conducted at 7 and 14 days post-exposure. Growth and survival trials were carried out for eight weeks using different larvae. There were no significant differences among treatments for whether or not larvae ate offered Daphnia for Day 7 (c2 =1.915, df =3) or Day 14 (c2 =1.283, df =3). For the trials on Day 7, Roundup concentration did not have a significant effect on the time the larvae took to consume 1, 2, or 4 Daphnia; however, exposure significantly increased the time the larvae took to consume three Daphnia (P=0.036). For the trials on Day 14, concentration did not have a significant effect on the time the larvae took to consume 1 or 2 Daphnia; however, Roundup significantly increased the time the larvae took to consume 3 (P=0.050) or 4 Daphnia (P=0.029). In the cover trials, there were no significant differences among treatments for the number of pokes required to elicit a behavioral response to hide during Day 7(c2 =9.458, df =6) or Day 14 (c2 =5.759, df =6). In the poke trials, there were no significant differences among treatments for the number of pokes required to elicit a fleeing response during Day 7 (c2 =1.336, df =3) or Day 14 (c2 =1.976, df =3). The behavioral response variables measured in the cover and poke trials were not significantly influenced by Roundup concentration, trial day, or size of the larvae. Roundup concentration and exposure week had a significant effect on growth (head width and body length) (P<0.001). Survival analysis showed that Roundup concentration did not have a significant effect on number of days survived (P=0.394). Thus, Roundup slowed prey consumption and significantly affected growth, suggesting that it could have a negative impact on larval dragonfly predation and growth rates, consequently harming their overall quality of life.

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Effects of Roundup on Behavior, Growth, and Survival of Larval Blue Dashers, Pachydiplax longipennis

Effects of Roundup on Behavior, Growth, and Survival of Larval Blue Dashers, Pachydiplax longipennis. KAYLEEN K. PARKER and CLAIRE FULLER, Biology Department, Murray State University, Murray, KY 42071.

The objective of this study was to determine if Roundup (active ingredient: Glyphosate) causes negative effects on behavior, growth, and mortality of larval Pachydiplax longipennis. Larvae were captured from rainwater-filled mesocosms at Hancock Biological Station in Murray, KY. Larvae were exposed to one of four concentrations of Roundup (0mg/L, 2.5mg/L, 5mg/L, or 10mg/L). Daphnia consumption, cover, and poke trials were conducted at 7 and 14 days post-exposure. Growth and survival trials were carried out for eight weeks using different larvae. There were no significant differences among treatments for whether or not larvae ate offered Daphnia for Day 7 (c2 =1.915, df =3) or Day 14 (c2 =1.283, df =3). For the trials on Day 7, Roundup concentration did not have a significant effect on the time the larvae took to consume 1, 2, or 4 Daphnia; however, exposure significantly increased the time the larvae took to consume three Daphnia (P=0.036). For the trials on Day 14, concentration did not have a significant effect on the time the larvae took to consume 1 or 2 Daphnia; however, Roundup significantly increased the time the larvae took to consume 3 (P=0.050) or 4 Daphnia (P=0.029). In the cover trials, there were no significant differences among treatments for the number of pokes required to elicit a behavioral response to hide during Day 7(c2 =9.458, df =6) or Day 14 (c2 =5.759, df =6). In the poke trials, there were no significant differences among treatments for the number of pokes required to elicit a fleeing response during Day 7 (c2 =1.336, df =3) or Day 14 (c2 =1.976, df =3). The behavioral response variables measured in the cover and poke trials were not significantly influenced by Roundup concentration, trial day, or size of the larvae. Roundup concentration and exposure week had a significant effect on growth (head width and body length) (P<0.001). Survival analysis showed that Roundup concentration did not have a significant effect on number of days survived (P=0.394). Thus, Roundup slowed prey consumption and significantly affected growth, suggesting that it could have a negative impact on larval dragonfly predation and growth rates, consequently harming their overall quality of life.