The Effects of Aging On the Foraging Behaviour of Steinernema Carpocapsae (Rhabdita: Steinernematidae)

Steinernema carpocapsae infective juvenile behaviour changes with age. Soon after emergence from the host cadaver, S. carpocapsae infective juveniles spend most of their time nictating. This behaviour enhances their host finding (ambushing) success. Between two and four weeks after emergence, their mobility increases and their nictation rate decreases. These alterations in behaviour suggested that a shift in foraging strategy from ambushing to a more mobile mode may occur. We tested this hypothesis by measuring changes in behaviours that may confer success to mobile foragers, including response to host cues and attachment to sedentary vs mobile hosts. We found that the success rate of ambushing declined with age, but there was no corresponding increase in the success rate of S. carpocapsae infective juveniles as mobile searchers, as measured in a sand column assay. We suggest that entomopathogenic nematodes do not alter their foraging strategy in response to unsuccessful search or aging.