﻿JOURNAL 
  ^J'Tv. 
  

  

  OF 
  THE 
  

  

  WASHINGTON 
  ACADEMY 
  OF 
  SCIENCES 
  

  

  Vol. 
  12 
  October 
  4, 
  1922 
  No. 
  16 
  

  

  ZOOLOGY. 
  — 
  The 
  possibility 
  of 
  control 
  of 
  Heterodera 
  radicicola 
  and 
  

   other 
  plant-injurious 
  nemas 
  by 
  means 
  of 
  predatory 
  nemas, 
  especially 
  

   by 
  Mononchus 
  papillatus 
  Bastian.'^ 
  G. 
  Steiner 
  and 
  HELEN 
  

   Heinly. 
  (Communicated 
  by 
  N. 
  A. 
  Cobb.) 
  

  

  I. 
  INTRODUCTION 
  

  

  The 
  investigations, 
  the 
  results 
  of 
  which 
  are 
  described 
  in 
  this 
  paper, 
  

   were 
  carried 
  on 
  from 
  December, 
  1921 
  to 
  the 
  end 
  of 
  May, 
  1922, 
  in 
  the 
  

   Osborn 
  Zoological 
  Laboratory 
  of 
  Yale 
  University, 
  in 
  collaboration 
  with 
  

   the 
  U. 
  S. 
  Department 
  of 
  Agriculture. 
  The 
  work 
  was 
  outlined 
  by 
  Dr. 
  

   N. 
  A. 
  Cobb 
  of 
  the 
  Bureau 
  of 
  Plant 
  Industry. 
  As 
  the 
  investigations 
  

   were 
  of 
  a 
  novel 
  nature, 
  numerous 
  methods 
  for 
  the 
  rearing 
  of 
  nemas 
  had 
  

   to 
  be 
  worked 
  out. 
  A 
  large 
  quantity 
  of 
  soil-material 
  was 
  collected 
  and 
  

   washed 
  by 
  a 
  combination 
  of 
  the 
  sieve 
  method 
  described 
  in 
  an 
  earlier 
  

   paper 
  by 
  Cobb 
  (7) 
  and 
  the 
  well 
  known 
  gravity-method. 
  The 
  daily 
  

   control 
  of 
  the 
  cultures, 
  transferring 
  the 
  predatory 
  nemas 
  to 
  fresh 
  

   conditions, 
  keeping 
  records 
  of 
  the 
  victims 
  and 
  adding 
  a 
  fresh 
  supply 
  

   of 
  food 
  requires 
  much 
  time 
  and 
  patience. 
  Heterodera 
  radicicola 
  

   material 
  was 
  kindly 
  sent 
  to 
  us 
  by 
  the 
  Connecticut 
  Agricultural 
  Station 
  

   and 
  from 
  the 
  Plant 
  Introduction 
  Garden 
  of 
  the 
  Department 
  of 
  Agricul- 
  

   ture, 
  Brooksville, 
  Florida. 
  We 
  wish 
  here 
  to 
  express 
  our 
  appreciation 
  

   for 
  this 
  assistance. 
  We 
  feel 
  indebted 
  to 
  the 
  authorities 
  of 
  Yale 
  

   University, 
  particularly 
  the 
  Osborn 
  Zoological 
  Department, 
  for 
  their 
  

   permission 
  to 
  carry 
  on 
  our 
  work 
  and 
  for 
  their 
  cordial 
  cooperation. 
  

  

  II. 
  THE 
  PROBLEM 
  

  

  Numerous 
  methods 
  of 
  control 
  of 
  plant 
  injurious 
  nemas 
  have 
  been 
  

   described 
  in 
  the 
  past. 
  Although 
  some 
  of 
  these 
  methods 
  are 
  very 
  useful, 
  

   yet 
  the 
  fact 
  remains 
  that 
  today 
  the 
  damage 
  done 
  by 
  nema-pests 
  is 
  

   enormous 
  and 
  is 
  still 
  increasing. 
  

  

  In 
  recent 
  years 
  the 
  study 
  of 
  free-living 
  nemas 
  has 
  been 
  greatly 
  

   increased, 
  and 
  as 
  a 
  result 
  the 
  problems 
  connected 
  with 
  nema-pests 
  

  

  * 
  From 
  the 
  Osborn 
  Zoological 
  Laboratory, 
  Yale 
  University, 
  New 
  Haven, 
  Conn., 
  in 
  

   collaboration 
  with 
  the 
  U. 
  S. 
  Department 
  of 
  Agriculture. 
  Received 
  September 
  9, 
  1922. 
  

  

  367 
  

  

  