H. Koltai et al., REPRODUCTION OF THE ENTOMOPATHOGENIC NEMATODE HETERORHABDITIS-BACTERIOPHORA POINAR, 1976 - HERMAPHRODITISM VS AMPHIMIXIS, Fundamental and applied nematology, 18(1), 1995, pp. 55-61
The present study was aimed at elucidating the mode of fertilization (
self vs cross) in 2nd generation non-male adults of the entomopathogen
ic nematode Heterorhabditis bacteriophora strain HP88. For this purpos
e dumpy mutants (Hbdpy-1 and Hbdpy-2) were used as genetic markers. Fo
rty hours after eggs hatching two types of juveniles were evident in t
he 2nd generation of either the wild-type or the mutant populations cu
ltured in vitro: half of the 2nd generation individuals developed to t
he 4th developmental stage (J4) with discernible reproductive systems.
The other individuals were, on average 1.4-2 times shorter and 1.6-3
times thinner (p < 0.05, t test) than the above described ''normal'' J
4. They were less developed then the J4 type and had no identifiable r
eproductive system. Among 550 of the J4 type juveniles (either wild-ty
pe of dumpy) that had been individually transferred to culture plates,
only 9 (i.e. 1.8%) gave rise to progeny. However, when dumpy non-male
adults, originating from J4 type juveniles were crossed to wild-type
males, 30-71% of them gave rise to progeny all of which were wild-type
, indicating that reproduction occurred solely by cross-fertilization.
These non-male adults were termed ''females''. Among 105 smaller-type
juveniles which had been individually transferred to culture plates,
80% reproduced indicating a high rate of self-fertilization i.e. a hig
h proportion of hermaphrodites. The smaller type juveniles were termed
''HJ'' (H for hermaphrodite). When dumpy HJ type juveniles were cross
ed with wild-type males, 70% (n = 30) gave rise to progeny. Each succe
ssful cross yielded both dumpy (46%-69%) and wild-type (31%-54%) proge
ny, indicating reproduction by self as well as cross-fertilization, re
spectively. The importance of the co-existence of these two reproducti
ve strategies and their implication to genetic studies are discussed.