Damselfly – Water Mite Interactions in Central Oregon Springs

Tracey M. Anderson

Biology 1101 Research Talk

2 November 2004

 

Slide 1: Oregon Scene

Slide 2: Oregon Map—Bridge Creek Watershed

Slide 3: Meyerıs Canyon—Semiarid landscape

Slide 4: Bridge Creek— historic overgrazing

Slide 5: Bridge Creek—Impacted steam, habitat changes, no riparian

Slide 6: Bridge Creek—beaver pond, habitat, biological diversity

Slide 7: Bridge Creek—habitat restoration, fair understanding of system, impacts

Slide 8: Meyerıs Canyon—small spring-fed habitat w/o fish; little studied

Slide 9: Stovepipe Spring—small spring; perennial habitat, uncharted biodiversity

Slide 10: Argia vivida with engorging mites: common component of insect fauna

Slide 11: Argia vivida (info from biological literature)

            Occurs throughout western North America, often associated with springs

 

            Exhibits a two-year life cycle with adult emergence synchronized by diapause

 

Larval and adult stages are predaceous

 

Association with mites unknown outside of central Oregon

 

 

Slide 12: Arrenurus (info from biological literature)

Over 1100 species described (> 200 North American species)

 

Free-living life stages predaceous on ostracods and other microcrustacea

 

Larvae parasitize Odonata and Diptera (Chironomidae and Culicidae)

 

Life stages rarely associated or described

 

 

Slide 13: Arrenurus hamrumi: scanning electron micrograph (SEM)

            Male, female, larva (binomial nomenclature, described species)

Slide 14: Illustrations for publication: larva

Slide 15: Illustrations for publication: adult

Slide 16: Water mite life cycle

            Egg                                          Hatching

 

            Larva                                      HOST LOCATION, ATTACHMENT

TO HOST, ENGORGEMENT,

DETACHMENT FROM HOST

 

 

            Nymphochrysalis                      Quiescent--Metamorphosis

 

            Deutonymph                            Free living predator

 

            Imagochrysalis                         Quiescent--Metamorphosis

 

            Adult                                        Free living predator, mating, oviposition

 

Slide 17: Intensity of water mite parasitism

                        Newly emerged damselflies

                        Damselflies with engorged mites (ca. 2 weeks old)

Slide 18: Argia vivida with fully engorged mites

Slide 19: Argia vivida with unengorged mites

 

 

Slide 20: Engorgement of mite larvae

                        Water mites must get big enough in order to survive

                        Engorgement takes ca. 2 weeks

Slide 21: Water mite life cycle: focus on detachment from host

Slide 22: Damselflies ovipositing: Mites detach during oviposition

Slide 23: Questions about water mite detachment

            Does oviposition provide the cued for mite detachment?

            Do mites preferentially detach over the aquatic habitat?

            Do mites detach from both male and female hosts?

            Could humidity be a cue in stimulating mite detachment?

Slide 24: Survey of mature damselflies

Slide 25: Experiments with caged damselflies

                        Land vs. H2O

                        Males vs. Females

                        H2O vs. Land-H2O vs. Land-Dry

Slide 26: Hand held psychrometer: Determined relative humidity

Slide 27: Damselfly cage H2O

Slide 28: Damselfly cage Land

Slide 29: Results:

            Mites detach over water

            Mites detach from male and female hosts

Slide 30: Land H2O—simulated aquatic habitat

Slide 31: Results

            Mites detach over water

            Mites do not detach away from water

            Humidity at simulated habitat is lower than ³real² habitat

Slide 32: Results: Humidity transect over aquatic habitat

            Zone of high humidity directly over habitat

Slide 33: Results: Perch height of damselflies

            Damselflies occur in zone of high humidity

Slide 34: Conclusions

            Many damselflies lose their mites prior to mating andovipositing

            Mites preferentially detach over the aquatic habitat

            Mites detach successfully from both male and female hosts

            High relative humidity is associates with high rates of mite detachment

Slide 35: The case for humidity stimulating detachment of engorged mite larvae

            Humidity provides a cue for both male and female hosts

            Damselflies often perch in areas of high humidity

            Mite larvae responding to a humidity cue would have a high probability of returning to             water (and thus be able to complete the life cycle)

Slide 36: Argia vivida with mitesŠ  Questions

 

 

 

Possible Discussion Questions:

 

What human impacts may have influenced the aquatic habitats in which the water mite research was conducted?

 

What is the value in investigating the biodiversity and ecology of small, out of the way (out of the public eye) habitats?

 

The association between Argia vivida and Arrenurus hamrumi is a parasitic association. Come up with other examples of parasitic associations.  What other types of symbiotic associations are there?  (Think of examples.)

 

What are some of the challenges that the water mites must overcome in order to complete the life cycle?

 

Thinking more generally, what are some of the challenges that all parasites must overcome in order to complete their life cycle? 

 

What are the consequences to parasites that ³overexploit² their hosts?

 

Discuss ways in which the hierarch of taxonomic classification and bionomial nomenclature were employed while presenting this research. 

 

Identify the steps in the scientific method that were employed in the research on the detachment of water mite larvae from their hosts.

            Observation

            Question

            Hypothesis

            Prediction

            Testing

            Date generation/evaluation

            Conclusions