Differential behaviour of the survival stages of Nacobbus aberrans (Nemata: Pratylenchidae) under sub-optimal environments

The biology of Nacobbus aberrans is poorly understood, including the behavi our of third and fourth stage juveniles (J3 and J4) under sub-optimal envir onmental conditions. To assess the effect of such conditions on J3 and J4, tomato plants infected by N. aberrans were grown under optimal conditions, and then were submitted to sub-optimal day length and temperature during th e periods when J3 or J4 predominated in the population. Even under optimal conditions, some J4 became quiescent. The suboptimal conditions prevented b oth J3 and J4 moults, and affected nematode development when optimal condit ions were restored: the J3 immediately moulted into J4, but many J4 remaine d quiescent and did not moult to the adult stage. These unanticipated diffe rences in how J3 and J4 endured unfavourable conditions suggest that the la tter stage is better adapted for survival.