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Indirect interactions between plants mediated by insect herbivores Alejandro Benhumea.

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Presentation on theme: "Indirect interactions between plants mediated by insect herbivores Alejandro Benhumea."— Presentation transcript:

1 Indirect interactions between plants mediated by insect herbivores Alejandro Benhumea

2 Water + - + - Associational Susceptibility Direct Interactions Indirect Interactions

3 Overview Plants Bugs Hypothesis Methods Data conclusion Q&A

4 Opuntia imbricata (cholla) & Opuntia phaeacantha (Prickly Pear)

5 Cholla Cacti Grows in cylindrical segments. Main plant density occurs at the base of los pinos. Structure prevents plant from being eaten by larger mammals Cholla are much more abundant than the prickly pear

6 Prickly Pear Cacti Fruits Cladodes

7 Juveniles/Adults Reproduction Predators Insect abundance Narnia pallidicornis

8 Adult Old Fruit Juvenile Proboscis

9 Reproduction Eggs Juveniles will depend on their host plant until they are adults. Juveniles that have hatched

10 Hypothesis 1 “Bug abundance on cholla cacti is greater on plants closer to the prickly pear cacti”.

11 Method Chose random Prickly pear and surveyed the surrounding cholla within a 15 m Radius. Surveyed 108 Cholla plants Took GPS coordinates for each plant with an accuracy of ~.5-1 meter to be able to measure plant distances.


13 Data 5-10 0 0-5 m 10-15 0.5 1 1.5 2 2.5 3 3.5 4 Bugs per cholla no significant effect of distance A A A 2006 Observational Data Distance from prickly pear

14 2004 Observational Data. 0 1 2 3 4 5 6 7 8 9 10 0-5 m5-10 m10-15 m bugs per plant significant effect of distance,P = 0.015 A B B Distance from prickly pear

15 04-06 comparison of prickly pear Fruit Production 0 10 20 30 40 50 60 70 80 # of fruits Per Plant 2006 fruits 2004 fruits

16 L Hypothesis 2 “insects released on high quality plants will stay closer than insects released on low quality plants. H

17 Methods Bug capture, marking and releasing. With a 24 hr wait time. 24 hr. I will be marking and releasing 30 insects per plant.


19 Fruits 15 Or 5 Fruits were taken from nearby prickly pear and placed on the plant that would be in the experiment. Prickly pear outside of experiment Prickly pear inside the experiment

20 Predictions By simulating Over Population, the bugs will move out with proportion to the available food source. Bugs will feed on fruit even though it had been cut off from the plant. I am expecting the dispersal to be gradual over 2 or 3 days. Changed it to 24 hours I am also expecting this experiment to follow closely with My first hypothesis.

21 Results of experimental release 0 0.02 0.04 0.06 0.08 0.1 0.12 0-55-1010-15 proportion recovered per plant low quality high quality no significant effects of treatment or distance Distance from prickly pear

22 Predators Jumping SpiderPraying Mantis Northern Mockingbird

23 Conclusion. The associational interaction from insects varies from one time frame to another In a Arid ecosystem climate changes over the years influence fruit abundance and the indirect interaction of plants through a mediated insect herbivore.

24 Questions ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

25 A Big Thanks to… Sevilleta LTER Fish and Wildlife Jennifer Johnson Brenda Nieto Andrew Romenger Ashwana Fricker Tom Miller

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