Mamestra brassicae

Scientific Name Mamestra brassicae (L.)
Synonyms Barathra brassicae
Common Names English: Cabbage moth; German: Kohleule; French: Noctuelle du chou; Spanish: Noctuido de la col; Swedish: Kålfly
Description The adult moth has a wingspan of 35-45 mm (1.36-1.75 inch). It is mottled in blackish-brown to gray colors. The caterpillar is about 40-45 mm (1.57-1.75 inch) long, mostly grayish-brown to green. Both adult and larva are very variable in coloration.

Biology

Damage

The caterpillars of M. brassicae feed on, and preferably bore themselves into, fruits, inflorescences and leaves of their host plants, mainly varieties of cabbage (Brassica sp.). At first, they produce numerous irregular holes in the outer layers of the head, then they advance deeper into its core. They soil the head by leaving behind a considerable amount of frass, which is in turn rapidly colonized by fungi and bacteria, causing rotting.
Even heads that are only superficially damaged lose in market value, often to the point of complete unmarketability. Those tunneled by larvae are unfit for human consumption.

Lifecycle

The adult moths occur from May to October. During this time, 1-3 generations are produced. If there is more than one, the generations often overlap later in the year.
Each female lays on average 500-2,000 eggs in batches of 30-60 on the lower surfaces of leaves. After 1-2 weeks, the larvae hatch and directly spread over the host plants. They molt 5 times. Young larvae feed on outer leaves etc.: older ones, however, become negatively phototactic and tunnel into the plant parts. After 4-8 weeks, they burrow about 5 cm (1.97 inch) deep into the ground where they build a cocoon and pupate. At this stage, they either fall into diapause for hibernation, or the adults emerge after some days. In some warm climates, there can also be a summer aestivation, i.e. the pupae diapause during the hot season.
Both the adult moth and the larva of M. brassicae are nocturnal and will, if possible, hide during full daylight.

Occurrence

Additional Crop Information

In spite of its name, M. brassicae is not completely limited to cabbage, but is very polyphagous and can also be found on many other crops, among them lettuce, chicory, spinach, tobacco, red beet, tomato, pea, beans, onion, potato, and even grape.

Agricultural Importance

The cabbage moth is found throughout Europe, the temperate regions of Asia and in some places in North Africa. It is absent in the Americas.
While the severity of infestations by the cabbage moth varies between years in the most northern and southern parts of its distribution range, it is an important pest in its central areas, where it can cause serious damage. In some cases, losses of up to 80% have been reported.

Control

Integrated Crop Management

Careful plowing after harvest in autumn will destroy a large proportion of the pupae by exposing them to predators and frost.
Provided there are not already pupae in the soil, covering beds with netting of mesh size 1.5-2 mm (0.058-0.078 inch) before plant emergence, or directly after planting, will largely prevent infestation. Early-sown (Jan/Feb) cabbage often shows little damage, as the heads are already well developed by the time the larvae appear.

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