250 likes | 352 Views
Indirect interactions between plants mediated by insect herbivores. Alejandro Benhu mea. Direct Interactions. Water. Associational Susceptibility. -. -. +. +. Indirect Interactions. Water. Overview. Plants Bugs Hypothesis Methods Data conclusion Q&A.
E N D
Indirect interactions between plants mediated by insect herbivores Alejandro Benhumea
Direct Interactions Water Associational Susceptibility - - + + Indirect Interactions Water
Overview Plants Bugs Hypothesis Methods Data conclusion Q&A
Opuntia imbricata (cholla)&Opuntia phaeacantha (Prickly Pear)
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
Prickly Pear Cacti Cladodes Fruits
Narnia pallidicornis Juveniles/Adults Reproduction Predators Insect abundance
Adult Proboscis Old Fruit Juvenile
Reproduction Eggs • Juveniles will depend on their host plant until they are adults. • Juveniles that have hatched
Hypothesis 1 “Bug abundance on cholla cacti is greater on plants closer to the prickly pear cacti”.
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.
4 A no significant effect of distance 3.5 3 A 2.5 A Bugs per cholla 2 1.5 1 0.5 Data 2006 Observational Data 5-10 10-15 0-5 m 0 Distance from prickly pear
2004 Observational Data. 10 significant effect of distance, P = 0.015 A 9 8 7 6 B 5 bugs per plant B 4 3 2 1 0 0-5 m 5-10 m 10-15 m Distance from prickly pear
04-06 comparison of prickly pear Fruit Production 80 70 60 50 2006 fruits # of fruits Per Plant 40 2004 fruits 30 20 10 0
L Hypothesis 2 • “insects released on high quality plants will stay closer than insects released on low quality plants. H
Methods Bug capture, marking and releasing. With a 24 hr wait time. 24 hr. I will be marking and releasing 30 insects per plant.
Fruits Fruits were taken from nearby prickly pear and placed on the plant that would be in the experiment. 15 Or 5 Prickly pear inside the experiment Prickly pear outside of experiment
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.
Results of experimental release 0.12 no significant effects of treatment or distance 0.1 0.08 proportion recovered per plant low quality 0.06 high quality 0.04 0.02 0 0-5 5-10 10-15 Distance from prickly pear
Predators Jumping Spider Praying Mantis Northern Mockingbird
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.
Questions ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
A Big Thanks to… • Sevilleta LTER • Fish and Wildlife • Jennifer Johnson • Brenda Nieto • Andrew Romenger • Ashwana Fricker • Tom Miller