Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks

 
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Ant suppression has
little effect on
termite activity and
plant decomposition
Sarah Bonney

Alan Andersen and Ben Hoffmann
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Ecological Importance

• 15,000 species described
worldwide with thousands more
undescribed

• Occupy every terrestrial habitat
except the poles

• >20% terrestrial faunal biomass

• Play many varied roles in the
ecosystem
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
The little rulers
    • Soil modification and nutrient cycling

    • Regulation of other arthropods
           Competition
           Territoriality
           Predation

    • Mutualisms
          Ant-tending
          Plant defense
          Seed dispersal

•     Seed predation
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Presence of ants and perceived
    predation risk alter termite
     behavior and distribution
Negative correlations of ants with termites
 • Arboreal – Goncalves et al 2005 - Brazil
 • Arboreal – Leponce et al 1999 – New Guinea
 • Transects – Dambros et al 2016 – Amazon rainforest

Presence of ants increases time taken for termites to occupy
baits
 • DeSouza et al 2009 - Brazil
Termites abandoned food resources quicker with
increased predation risk
 • Korb and Lisenmair 2002 – Ivory Coast

Ant suppression increased bait consumption by termites
 • Parr et al 2015 – South Africa
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
The little things that run the world: Ecological responses
            to the removal of a dominant faunal group in an
PhD         Australian tropical savanna
project:    1.How will termites respond to the removal of their most
Chapter 4   important predator?

            2. How does ant suppression affect the rate of decomposition
            of leaf litter, wood and grass?
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Study design
Two sites with contrasting ant communities:

    TWP: High abundance and diversity             TERC: Low abundance and diversity
       Primarily dominant species                     Few dominant species
       Annual fire frequency                          Low fire frequency

                                                                        Control
    BACI design
                                                                                  3 x paired
    Treatment area 50 x 50 m                                                      plots/site
                                                                           30 m
    Inner sampling area 30 x 30 m             Treatment plot    Control plot
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Ant suppression and
sampling

• Baited using catfood mixed with honey and
confidor (imacalroprid).
  • YR1 - Every 3 months
  • YR2 - Every month

• Sampled ants using pitfall traps and catfood
lures
   • Every 6 months
   • Additional lure sample 2 months after
      baiting ceased
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Termite community and
activity
  Number of Encounters
    • Transect searches
       • 100 minutes of active
         searching/plot

    • Cellulose lures
       • Paper towel lures buried just under
          the surface – checked ~ every 11
          days

  Mound growth
    • Basal circumference + height = volume
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Termite community and
activity
Attack rate and consumption
Toilet paper and wood sticks buried just
under the surface. Amount consumed
scored

   0 = 0% consumed, 1 = 1-25%, 2 = 26-
   50%, …….. 5 = 100%

Decomposition
Wood, grass and leaf litter

   • Left on soil surface for 6 months
Ant suppression has little effect on termite activity and plant decomposition - Sarah Bonney Alan Andersen and Ben Hoffmann - SANParks
Sampling schedule
                              Pre-treatment         YR1                 YR2                 YR3
   Ants                                           Oct 2015
                                                  Jan 2016         Monthly from Sep 2016 to Feb 2018
                Baiting
                                                  Apr 2016               (excluding Dec 2016)
                                                  Jul 2016
                                                  Nov 2015
                                Nov 2014                             Mar 2017
                Pitfalls                          Apr 2016
                                Sep 2015                             Oct 2017
                                                  Sep 2016
                                                  Oct 2015
                                Apr 2015                             Mar 2017         Mar 2018 (TWP
                 Lures                            Feb 2016
                                Aug 2015                             Oct 2017              only)
                                                  Sep 2016

  Termites       Lures          May 2015          May 2016           May 2017

               Transects                          Dec 2015           Jan 2017            Feb 2018

             Consumption     Mar to May 2015   Mar to May 2016    Mar to May 2017

               Mounds           Aug 2015          Apr 2016           Apr 2017

             Decomposition                     Jan to June 2016   Jan to June 2017
Results - Interpretation                              Treatment plots presented as % of control plots

                                     Positive
Percent of control

                                     response         No
                                                   response      Negative
                                                                 response
                                                                            Treatment = control

                     Pre-treatment              Post treatment
Ant suppression effectiveness
                                                   pitfalls
                                                   lures

                                            TERC
                                 TWP

               80% suppression at TWP   No suppression at TERC

* p
Termite encounters and species richness
                      TWP Transects                                                 TWP Lures
300
                                                           450
250                                                        400
                                                           350
200
                                                           300

150                                                        250
                                                           200
100                                                        150
                                                           100
 50
                                                           50
  0                                                         0
       Pre      YR1       YR2   Pre         YR1      YR2         Pre      YR1       YR2     Pre         YR1          YR2
 -50
             Encounters               Species richness                 Encounters                 Species richness

                  No significant change in encounters or species richness
Termite encounters and species richness
                      TERC Transects                                                TERC Lures
                                                           300
 500
 450                                                       250
 400
                                                           200
 350
 300
                                                           150
 250
 200
                                                           100
 150
 100                                                       50
 50
  0                                                         0
       Pre      YR1       YR2   Pre         YR1      YR2         Pre      YR1         YR2        Pre         YR1          YR2
             Encounters               Species richness                 Encounters                      Species richness

                      No significant change in encounters or species richness
Termite encounters – feeding guilds
                         TWP Transects                                              TWP Lures
                                                          500
 500
 400                                                      400
 300                                                      300
 200              *                                       200
 100                                                      100
   0                                                        0
-100     pre     YR1       YR2      pre     YR1     YR2   -100       pre     YR1     YR2     pre       YR1        YR2
                 Wood                      Debris                            Wood                     Debris

                          TERC Transects                                             TERC Lures
   400                                                     1000
   350
   300                                                       800
   250
                                                             600
   200
   150                                                       400
   100
    50                                                       200
     0
                                                                 0
           pre     YR1       YR2     pre     YR1    YR2                pre     YR1     YR2      pre       YR1       YR2
                                                            -200
                  Wood                     Debris                             Wood                       Debris           *p
Mound growth
                                      YR1                                   YR2
                         Control            Treatment        Control              Treatment
 TWP
 No. measured               18                    20             14                     15

 No. damaged/lost            4                    3               5                     7

 No. with no growth          6                    6               3                     1

 No. growing                 8                    11              6                     7
 Mean growth (cm2)       1,618.14             8,484.4         333.83               58,224.38       NS
                (± SD)   (± 768.14)          (± 12,676.91)   (± 264.21)            (± 96,478.63)

 TERC
 No. measured               35                    33             29                     33

 No. Damaged/lost           17                    18             13                     18

 No. with no growth          0                    0               0                     0

 No. growing                18                    15             16                     15
 Mean growth (cm2)        829.57              651.78         2,464.97               2,133.3        NS
                (± SD)   (± 297.36)           (± 303.49)     (± 2,306.77)           (± 130.21)
Attack rate of lures
            TWP Paper               300
                                                  TWP Wood
200
                                    250
                                                       **
150                                 200
100                                 150

 50                                 100

  0                                 50
      Pre          YR1        YR2    0
                                           Pre          YR1        YR2
               no. attacked
                                                    no. attacked

            TERC Paper                            TERC Wood
140                                 300
120
100                                 200
 80
 60
                                    100
 40
 20
  0                                   0
      Pre          YR1        YR2           Pre         YR1        YR2
                                    -100
               no. attacked                         no. attacked
                                                                         **p
Consumption                      250
            TWP Paper                         TWP Wood
                                 200
150                              150
100                              100
 50                              50

  0                                0
      Pre         YR1      YR2          Pre         YR1      YR2

               intensity                         intensity

            TERC Paper                        TERC Wood
200                               400

150                               300

100                               200

                                  100
 50
                                   0
 0
                                        Pre        YR1       YR2
      Pre        YR1       YR2   -100
                                                 intensity
               intensity
Decomposition bags
 400                             TWP
 300

 200

 100
                                                 *
   0
        YR1          YR2   YR1             YR2   YR1           YR2
 -100
              Wood                Litter               Grass

                                 TERC
 350
 300
                           *
 250
 200
 150
 100
  50
   0
        YR1          YR2   YR1             YR2   YR1           YR2
              Wood                Litter               Grass
Results summary
                                                                TWP                                              TERC
             Ant abundance                               Drop of 80% by YR2                                    No change

 Termite abundance, species richness and                      No change                                        No change
              composition

             Feeding groups                  Lower abundance of wood feeders in YR1 in                         No change
                                                            transects

                Mounds                        Higher in treatment plots but variable - NS                     No difference

           Attack rate of lures                Higher attack rate of wood lures in YR1                        No difference

          Consumption of lures                              No difference                                     No difference

             Decomposition                 Lower decomposition of grass in treatment plots   Higher decomposition of leaf litter in treatment
                                                              in YR1                                         plots in YR1

 Conclusion: Ant suppression has caused small and inconsistent changes
             Contrasting results to those of previous studies
Possible explanations

1. Ants are not so abundant in Australia

2. Termites are not such as important dietary component of
Australian ants

3. Australian termites are more resilient
Thank you!
Any Questions?
References
• Desouza et al (2009) Trophic controls delaying foraging by termites:
  reasons for the ground being brown? Bulletin of Entomological
  research, 99, 603-609
• Dambros et al (2016) Association of ant predators and edaphic
  conditions with termite diversity in an Amazonian Rainforest.
  Biotropica 48(2), 237-245
• Leponce et al (1999) Community interactions between ants and
  arboreal-nesting termites in New Guinea coconut plantations.
  Insectes soc 46, 126-130
• Gonvalves et al (2005) Predation and interference competition
  between ants and arboreal termites. Sociobiology 46(2)
• Parr et al (2005) Suppression of savanna ants alters invertebrate
  composition and influences key ecosystem processes. Ecology 97(6)
  1611-1617
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