ATTRACTIVENESS OF CABBAGE MAGGOT (DIPTERA, ANTHOMYIIDAE) TO ENTOMOPATHOGENIC STEINERNEMATID NEMATODES

The cabbage maggot, Delia radicum (L.), an important pest of crucifer crops, is a good candidate for control by nematodes, because different parts of its life-cycle occur in the soil. To understand the interact ion between nematodes and both eggs and larvae of the cabbage maggot, we examined their attractiveness to the Steinernema carpocapsae All st rain in muck soil. We also quantified the ability of some steinernemat ids to intercept migrant Ist instars before root penetration and to fo llow larvae into root tunnels in a seminatural environment (soil, plan t, host). S. carpocapsae All strain was not attracted by cabbage maggo t eggs, whereas they oriented toward newly hatched cabbage maggot larv ae. S. carpocapsae All and UK (Biosys 252) strains killed a significan t proportion of migrant cabbage maggot larvae before they could penetr ate into radish roots. Although most steinernematids tested followed l arvae into the radish roots, only S. feltiae (=bibionis) induced signi ficant infection. Our results indicate that steinernematids have the a bility to intercept cabbage maggot 1st instars and to follow and infec t developing cabbage maggot larvae in roots. However, studies must be undertaken to select the best interceptor and tunnel follower nematode species to control the cabbage maggot, as well as to determine the be st timing of nematode application.