Improving the control of the cabbage moth (Mamestra brassicae) with entomopathogenic nematodes

The cabbage moth (Mamestra brassicae) is a cryptic pest that feeds mainly on the leaves of cruciferous crops. It resides mostly at the underside of these leaves, which makes it a difficult target for chemical or biological control agents applied by spray applications. This research focuses on the use of a yeast extract as an attractant in a spray suspension with entomopathogenic nematodes (EPN). This attractant might lure the cabbage moth out of its normal habitat, towards the EPN, potentially improving the biological control capacity of the EPN.
The effect of a yeast extract on the mortality and the feeding preference of the cabbage moth and the amount of leaf damage done by the cabbage moth.
In this lab test, large square petri dishes were filled with two cauliflower leaf circles in opposite corners. The leaf circle in one corner received a control treatment (i.e., spraying with water), while the leaf circle in the opposite corner was (a) not treated, (b) treated with water, (c) treated with an EPN spray, or (d) treated with an EPN spray with a yeast extract added to it. A cabbage moth larva was put in a third corner of each petri dish. The mortality, feeding preference and the leaf damage done by these larvae were followed during 5 days after starting of the experiment.
The test revealed that the EPN caused a higher mortality of the cabbage moth, when they were sprayed together with a yeast extract. It did however not reveal the mode of action of the yeast extract. There was no significant difference between the feeding preference within petri dishes.No consistent effect of yeast on the leaf damage done by the cabbage moth could be distinguished.
The yeast extract was taken into a field experiment to test if it can effectively improve control of the cabbage moth. These results will be presented at the conference