I. Glazer et al., BIOLOGICAL CHARACTERISTICS OF THE ENTOMOPATHOGENIC NEMATODE HETERORHABDITIS SP IS-5 - A HEAT TOLERANT ISOLATE FROM ISRAEL, Nematologica, 42(4), 1996, pp. 481-492
Entomopathogenic nematode isolate (IS-5), from under the canopy of fru
it trees in the arid ''Negev'' region of Israel was found to be highly
tolerant to temperatures above 30 degrees C. Morphological measuremen
ts did not distinguish this isolate from Heterorhabiditis bacteriophor
a Poinar, 1976. However, DNA extracted from four different genotypes (
Heterorhabditis sp. IS-5, HP88 and IS-3 and H. megidis HSH2) amplified
with six random primers yielded products from which it was calculated
that the similarity between IS-5 and HP88 was 20%, between IS-3 and H
P88 85% and between IS-3 and H. megidis 15.6%. Two hours at 37 degrees
C killed 79% HP88 infective juveniles but only 18% IS-5. Eight hours
at 37 degrees C killed 87% of HP88 but only 28% of IS-5. One hour at 4
0 degrees C killed all infective juveniles of the HP88 isolate but onl
y 26% of IS-5. Heat shock treatment for 2 h at 37 degrees C before exp
osure to 40 degrees C enhanced the survival of IS-5 juveniles to 43% a
s compared with non heat-shocked control. At 25 degrees C IS-5 caused
100% mortality of Galleria melioneila larvae after 36 h and HP88 after
48 h. At 30 degrees C IS-5 caused 100% mortality in 24 h. The average
number of nematodes in cadavers exposed to IS-5 and HP88 for 48 h ran
ged from 15 to 16.3 and 7.3 to 10.8, respectively. At 25 degrees C bot
h these heterorhabditid isolates produced an average of 90,000 infecti
ve juveniles per cadaver. At 30 degrees C and 33 degrees C yields of I
S-5 increased by 10% but those of HP88 reduced by 90%. At each tempera
ture IS-5 juveniles emerged 2-3 days earlier than HP88.