M. Abuhatab et al., ROLE OF PROTEASES IN PENETRATION OF INSECT GUT BY THE ENTOMOPATHOGENIC NEMATODE STEINERNEMA-GLASERI (NEMATODA, STEINERNEMATIDAE), Journal of invertebrate pathology, 66(2), 1995, pp. 125-130
The entomopathogenic nematode Steinernema glaseri enters into the host
through natural openings and penetrates through the internal walls be
fore entering into the hemocoel. In the present study we found that in
addition to mechanical means used for penetration, entomopathogenic n
ematodes release proteolytic enzymes. When nematodes were treated with
protease inhibitors and injected into Galleria mellonella gut, the pe
rcentage mortality of G. mellonella was reduced to 17 +/- 2 for iodoac
etamide and 30 +/- 4 for 1,10-phenanthroline-treated nematodes compare
d to 75 +/- 3 for control after 18 hr post anal injection. Treatment o
f the nematodes with combinations of protease inhibitors and protein s
ynthesis inhibitors did not result in a synergistic effect on G. mello
nella mortality. Nematode penetration of G. mellonella gut after their
treatment with iodoacetamide and 1,10-phenanthroline was reduced to 1
3.4 +/- 1.1 and 15.6 +/- 1.9, respectively, after 12 hr postinjection
through the anus. The antibiotic chloramphenicol inhibited the symbiot
ic bacteria Xenorhabdus poinarii cells and reduced the average viable
number retained/100 nematodes to 40 +/- 30. Cycloheximide delayed G. m
ellonella mortality but not gut penetration. This suggests that it mig
ht have some toxic effect on the nematodes. (C) 1995 Academic Press, I
nc.