Effects of mechanical stimulation and crowding on Mylonchulus dentatus

Abstract

To study the effects of crowding and cannibalism, adult and juvenile M. dentatus were placed in the plastic wells containing 3 ml tap water and kept in the dark for 12 hr at 27 ± 2°C. Head movements and the numbers of active, inactive and injured individuals were then recorded using a microscope. There were 10 replicates of each of the combinations of adults and juveniles. Groups of varying numbers of adults and juveniles placed in the plastic wells showed similar rates of head movement (40-56/ minute) irrespective of the number of individuals in the well. General activity was very variable but increased crowding resulted in more nematodes injured. For example, in a well with 15 adults and 5 jUYeniles, 6 adults and 4 juveniles were injured; with 5 adults and 5 juYeniles, 1 adult and 2 juveniles were injured. It is concluded that when the density of predators is high and prey IS not available the nematodes probably resort to cannibalism.