INHIBITION OF CRICONEMELLA-XENOPLAX EGG HATCH BY PSEUDOMONAS-AUREOFACIENS

Nine fluorescent pseudomonad strains and one strain each of Escherichi a coli and Rhizobium fredii were tested for potential to inhibit Crico nemella xenoplax egg hatch. One strain, Pseudomonas aureofaciens BG33, and its genetically modified derivative, BG33CL1R, effectively inhibi ted egg hatch at 2.0 X 10(8) cfu mi-1. Strain BG33CL1R inhibited egg h atch by 5, 50, and 95% when present at 1.0 X 10(7), 4.8 X 10(7), and 2 .4 X 10(8) cfu ml-1, respectively. Eggs were sensitive to BG33CL1R fro m the time of deposition until second-stage juveniles were formed insi de eggs 6.5 days later. In contrast, activity of second-stage juvenile s and adults did not appear to be affected by incubation in BG33CL1R f or up to 2 wk. Seven strains of P. aureofaciens and one strain each of E. coli, P. chlororaphis, and R. fredii did not inhibit egg hatch in similar tests. Therefore, general septic conditions apparently are not responsible for egg kill. The potential for P. aureofaciens BG33 and BG33CL1R to kill C xenoplax eggs could explain in part their suppressi on of nematode population increase in greenhouse tests.