The  Effect  of  Lawn  Treatment  on  Nematode  Diversity  Around    Lewis  &  Clark  College  

  By  Bobby  Brandt  ‘16  and  Melanie  Morris  ‘15  INTRODUCTION  

METHODS  

RESULTS   DISCUSSION  

REFERENCES  

ACKNOWLEDGEMENTS  

     Healthy   ground   soil   is   essenGal   to  providing  ecosystems  with  a    with   a   firm   base   for   maintaining   the   wellbeing   of   plants   and  animals1.   The   health   of   the   soil   is   deeply   interconnected  with   the  acGvity   of   detriGvores,   organisms   that   break   down   waste   in   the  environment,   and   their   predators.   Both   groups   contain   a   wide  range  of    diversity   that   fulfill   various   roles   to  maintain   soil  health.  These   organisms   are   sensiGve   to   soil   condiGons,   and   any  adjustments   in   the   condiGons   can   cause   changes   in   both  populaGons.  With   the  expansion  of  human   land  development,   soil  condiGons   are   rapidly   changing,   and   could   be   puOng   soil  invertebrate   populaGons   in   jeopardy1.   However,   we   can   use   soil  invertebrate   diversity   as   a   bioindicator   for   our   impact   on   soil  health2.          The  diversity  of  oil  nematodes,  the  predators  of  many  detriGvores,  has  been  idenGfied  as  being  integral  to  soil  health3.  Soil  nematodes  are   parGcularly   good   candidates   to   be   used   as   bioindicators   for  human  impact  on  soil  health  for  the  following  reasons:    •  They  are  abundant  worldwide  •  They  are  widely  diverse    •  They  are  relaGvely  easy  to  collect  •  They  are  highly  sensiGve  to  changes  in  soil      

 

    In   this   study,   we   aUempt   to   show   the   impact   of   human   lawn  treatments   around   Lewis   &   Clark   College   on   soil   nematode  diversity,  and  we  present  a  working  method  for  future  nematode  collecGons.      

HYPOTHESIS    We  predict  that  there  will  be  more  nematode  diversity  in  the  forest   areas   than   the   treated   lawn   areas   because   the   soil  condiGons   in   the   forest   are   assumed   to   be   less   affected   by  human   chemical   treatments2   and   plant   diversity   is   less  homogenous  than  on  the  lawn.        

We  would  like  to  thank  Dr.  Greta  Binford,  Dr.  Greg  Hermann,  and  Dr.  Michael  Ailion  for  their  advice  and  support  for  this  project.  We  would  also   like  to  thank  the  Hermann  lab  for  sharing  worm  maintenance  materials   and  E.   coli  plates.   Finally,  we  would   like   to   thank   the   Lewis  &  Clark  Biology  Department  for  providing  the  resources  that  made  this  project  possible.    

1.Doran,  J.  and  Zeiss,  M.  2000.  Soil  health  and  sustainability:        managing  the  bioGc  component  of  soil  quality.  Applied  Soil  Ecology.  15(1):  3-­‐11  2.  Yeates,  G.  and  Bongers,  T.  1999.  Nematode  Diversity  in  Agroecosystems.  Agriculture,  Ecosystems  &  Environment  74(1):  113-­‐35.  3.  EUema,  C.  1998.  Soil  Nematode  Diversity:  Species  Coexistence  and  Ecosystem  FuncGon.  Journal  of  Nematology.  30(2):159-­‐169.  4.  De  Ley,  P.  “A  quick  tour  of  nematode  diversity  and  the  backbone  of  nematode  phylogeny”.January  25,  2006,  WormBook,  ed.  The  C.  elegans  Research  Community,  WormBook,  doi/10.1895/wormbook.1.41.1,  hUp://www.wormbook.org.  Web.  4  October  2014.  5.  Barrière  A.,  Félix  M.  A.  “IsolaGon  of  C.  elegans  and  related  nematodes”.  May  2,  2014.  WormBook,  ed.  The  C.  elegans  Research  Community,  WormBook,  doi/10.1895/wormbook.1.115.2,  hUp://www.wormbook.org.  Web.  4  October  2014.    

FUTURE  DIRECTIONS    

We  tried  many  methods  for  nematode  collecGon  using  old  fruit   (Table  1).  However,  some  fruits  proved   to   be   more   effecGve   for   nematode   collecGons   than   others.   Apples   disintegrated   too  quickly  to  be  recovered,  and  nematodes  could  not  be  collected  from  grape  samples.  The  best  fruit  seems  to  be  the  banana,  as  nematodes  will  colonize  in  the  peel  and  the  peel  does  not  disintegrate  and  is  likely  less  palatable  to  local  wildlife.    

Table  1:  Results  from  fruit  methods  for  collecOng  soil  nematodes.    

Examples  of  IdenOfied  Nematodes    

Figure  2.  Diplogastrid  idenOfied  by  mouthparts  from  the  forest  area.    

Figure  3.  RhabdaOs  idenOfied  by  mouth  parts  from  the  lawn  area.    

Nematode  CollecOon  Fruit   Method:   Chunks   of   fruit   were   buried   approximately   1.5cm  under  soil  in  either  the  Lewis  &  Clark  College  Forest  or  on  a  treated  lawn   area  with   exposed   soil.   The   samples  were   lel   six   to   twelve  days  and  then  collected.  The  fruit  was  put  on  a  bacteria  lawn  of  E.  coli  and  the  nematodes  were  allowed  one  hour   to  crawl  onto  the  plate.  Soil  Method:  Approximately  one   tablespoon  of   soil  was   scaUered  on  an  E.   coli   lawn  and  moistened5.  Nematodes   that   crawled  onto  the  lawn  within  24  hours  were  collected.      Nematode  Maintenance  Nematodes  were  kept  at  room  temperature  and  “chunked”  onto  new  plates  when  old  one  became  crowded  (every  2-­‐3  days)      Adult  nematodes  were  picked  onto  an  agar  pad  and  suspended  in  a  soluGon  of   levamisole   to   immobilize   them,  and  they  were   imaged  using  AxioImager  at  100x  zoom.    We  compared  the  images  and  characterisGcs  to  known  organisms  classified  in  the  WormBook4,5.    

MounOng  Specimens  and  Imaging  

IdenOfying  Nematodes  

                               

Fruit  Number  of  Samples  in  Forest  

Number  of  Samples  on  

Lawn  ProtecGon   Days  Lel  

on  Soil  Sample  

Recovered  Nematodes  

Found  Nematode  Eggs  

Found    

Grape   3   3   Buried  only   7   Yes   None                    None  

Apple   4   4   Petri  dish  cover  and  buried   7   No   N/A                    N/A    

Apple   1   1   Buried  only   12   No   N/A                    N/A  Banana   1   1   Buried  only   12   Yes   Yes                    Yes    

Banana   1   1   Buried  only   12   No   N/A                    N/A  

Banana   1   1   Cup  cover  and  buried     6   Yes   Yes   None  

We   have   provided   a   starGng   point   for   many   future  experiments   that   wish   to   look   at   nematode   diversity   and  abundance   as   a   bioindicator   for   soil   health.   Future  experiments  should  consider  the  following:    •  Increase  sample  size  and  Gme  of  collecGons  •  Include  non-­‐bacteria  feeding  nematodes  •  Increase  of  soil  collecGon  by  taking  soil  cores  •  Measure  soil  condiGons  including:  

o  pH  o  Moisture  o  Mineral  content  

•  Refine  taxonomic  classificaGon  by  using  molecular  data  

 

We   expect   groups   that   take   these   future   direcGons   into  consideraGon  will   gain   greater   insight   on   human   impact   on  soil  condiGons  around  Lewis  &  Clark  College.    

IllustraGon  from  Barrière,  20145  

IllustraGon  from  Barrière,  20145  

                   

Family     LocaGon   Method  of  CollecGon  

Number  of  Nematodes    Collected    

Number  of  Egg  Clusters  Collected    

Rhabditae        Subfamily:        Diplogastrid  

Rhabditae     Forest   Banana  6  Days   1   0  

Rhabditae     Forest   Soil   1   0  

Rhabditae     Lawn   Banana  12  Days   1   1  

Rhabditae     Lawn   Banana  6  Days   1   0  

Rhabditae     Lawn   Soil   1   0  

Table  2:  Nematodes  collected   from  the  different  locaOons   idenOfied   to   the   family   level.   There   is  no   significant   difference   in   the   diversity   or  abundance  of  nematodes  between  the  two  areas.  

Nematode  Diversity    We   imaged  and   idenGfied  all   collected  nematodes   to   the   family   level,   which  was   the   highest   taxonomic   resoluGon  possible.   Molecular   analysis   would  need  to  be  done  for  further  resoluGon.  A   comparison   between   the   number   of  families   found  between   the   forest   and  lawn   locaGons   shows   that   there   is   no  significant   difference   in   nematode  diversity,   as   all   specimens   are   in   the  Rhabditae   family   (Table   2).   Because  one  nematode  specimen  was  collected  from   each   type   of   sampling   at   each  locaGon,   there   is   also   no   significant  difference   between   the   abundance   of  nematodes  in  either  locaGon.    

      The   goal   of   this   study   was   to   use   nematode   diversity   as   a  bioindicator   for   soil   health   around   Lewis   &   Clark   College.   We  hypothesized  that  we  would  find  more  nematode  diversity,  in  the  form   of   a   greater   number   of   families,   present   in   our   forest  samples   when   compared   to   the   lawn   samples.   However,   our  preliminary   data   suggest   that   there   is   no   significant   difference  between   the  diversity   of   nematodes   in   either   condiGon,   as   only  one  family  could  be  idenGfied  from  all  of  the  samples.  Molecular  analysis  would  refine  the  taxonomic  resoluGon  and    indicate  show  differences  in  nematode  diversity  that  we  cannot  idenGfy  now.           Although   our   data   do   not   show   significant   differences,   it   is  important   to   conGnue   working   on   valid   methods   to   monitor  human   impact   on   soil   invertebrate   diversity.   The   work   of   soil  invertebrates,   including   nematodes,   improves   the   quality   of   the  soil  and  supports  healthy  ecosystems,  making  a  healthier  planet.  It   is   therefore   important   that   we   monitor   our   impact   on   soil  invertebrates,  so  we  do  not  end  up  harming  the  rest  of  the  world.    

     Forest              Banana  12  Days                          1                                            0  

Family Location Method of Collection Number of Nematodes Collected

Number of Egg Clusters

Collected

Rhabditae Subfamily: Diplogastrid Rhabditae Forest Banana 6 Days 1 0

Rhabditae Forest Soil 1 0 Rhabditae Lawn Banana 12 Days 1 1

Rhabditae Lawn Banana 6 Days 1 0

Rhabditae Lawn Soil 1 0

Forest Banana 12 Days 1 0