This study measured trap induction and trapping on agar disks as affected by juvenile stages (J1, J2, J3, and J4) of the nematode Caenorhabditis elegans and by species of nematode-trapping fungi. Eight species of nematode-trapping fungi belonging to the family Orbiliaceae and producing four kinds of traps were studied: adhesive network-forming Arthrobotrys oligospora, A. vermicola, and A. eudermata, constricting ring-forming Drechslerella brochopaga, and Dr. stenobrocha, adhesive column-forming Dactylellina cionopaga, and adhesive knob-forming Da. ellipsospora, and Da. drechsleri. The number of traps induced generally increased with increasing juvenile stages of C. elegans. The ability to capture the juveniles tended to be similar among isolates that produced the same kind of trap but differed among species that produced different kinds of traps. Trapping by Dr. stenobrocha and Da. cionopaga was correlated with trap number and with juvenile stage. A. oligospora and A. vermicola respectively captured more than 92 and 88% of the J1, J3, and J4 but captured a lower percentage of J2. The knob-producing isolates captured more younger than elder juveniles. Partial correlation analyses demonstrated that the trap induction of the most fungal species positively correlated with the juvenile size and motility, which was juvenile stage dependent. Overall, trap induction and trapping correlated with C. elegans juvenile stage (size and motility) in six species of trapping fungi.

Lectin binding sites on the surface of Meloidogyne incognita Races 1, 2, 3, and 4; M. javanica; M. arenaria Races 1 and 2; and M. hapla Races A and B were determined with lectins conjugated to fluorescein isothiocyanate or colloidal gold. The amphidial exudate, which was demonstrated histochemically to contain carbohydrate, was the principal binding site. Some lectins also bound to the external cuticular surface. Species and race specific binding patterns were observed for both amphidial and cuticular binding sites.

The occurrence and distribution of several lectin binding sites on the outer surfaces of eggs, preparasitic second-stage juveniles (J2), parasitic second-stage juveniles (PJ2), females, and males of two tylenchid nematodes, Anguina tritici and Meloidogyne incognita race 3, were compared. In both species, a greater variety of lectins bound to the eggs than to other life stages; lectin binding to eggs was also more intense than it was to other life stages. Species-specific differences also occurred. More lectins bound to the amphids or amphidial secretions of M. incognita J2 than to the amphids or amphidial secretions of A. tritici J2. Lectins also bound to the amphids or amphidial secretions of adult male and female A. tritici, but binding to the cuticle occurred only at the head and tail and was not consistent in all specimens. Canavalia ensiformis and Ulex europaeus lectins bound specifically to the outer cuticle of M. incognita. Several other lectins bound nonspecifically. Oxidation of the cuticle with periodate under mild conditions, as well as pretreatment of the nematodes with lipase, markedly increased the binding of lectins to the cuticle of A. tritici J2 but not, in most cases, to M. incognita J2 or eggs of either species.

The conidia of the endoparasitic fungus Meria coniospora (Deuteromycetes) had different patterns of adhesion to the cuticles of the several nematode species tested; adhesion in some species was only to the head and tail regions, on others over the entire cuticle, whereas on others there was a complete lack of adhesion. After adhesion, the fungus usually infected the nematode. However, adhesion to third-stage larvae of five animal parasitic nematodes, all of which carry the cast cuticle from the previous molt, did not result in infection. M. coniospora infected animal parasitic nematodes when this protective sheath was removed. Seven preparations of sialic acid (N-acetylneuraminic acid) gave three types of response in adhesion-infection of nematodes:(i) a significant reduction in conidial adhesions;(ii) no interference with adhesion, but a 10-day delay in infection; and (iii) a delay in infection by 2 to 3 days. The current results support previous findings indicating involvement of sialic acids localized on nematode cuticles in recognition of prey by M. coniospora.