Pest Identification

Identifying different life stages

Eggs are yellow/white and subspherical, measuring about 0.6 in width and 0.4 mm in height, with longitudinal ribs.

Larvae measure up to 45 mm in length and are green/grey in colour with black spots and pale stripes.

Pupae are red/brown and measure about 20 mm in length.

Adults have a wingspan of up to 45 mm. Forewings are brown/green with black/brown patterns, and hindwings are light grey in colour.

Life Cycle

Mamestra brassicae may undergo up to 3 generations each year, and adult moths occur between May and October. Each female may lay up to 2 000 eggs, which are deposited on the underside of leaves in batches of up to 60 eggs. Larvae hatch after up to 12 days, and undergo six larval instars. After up to 50 days larvae pupate within a cocoon in the soil and either enters diapause under unfavourable conditions, or adults emerge after up to 15 days in favourable conditions.

Insect stage that causes damage

Larvae inflict feeding damage to a wide variety of cultivated plants, with more mature larvae causing the greatest damage, however young larvae may skeletonise leaves when the pest population is large. Mature larvae tunnel into plants, and their faeces encourage fungal and bacterial growth. Most damage is inflicted by the second larval generation.

When and where to identify

Both larvae and adults are nocturnal and are therefore difficult to detect in the crop and it may be preferable to examine for feeding damage instead. Sticky traps, pheromone traps and light traps can be used to monitor adult populations.

Geographical location

Mamestra brassicae occurs throughout Europe, and in areas of Asia and northern areas of Africa.

Damage

Timings

Damage is largely inflicted by second generation larvae, as these typically occur between July and September.

What and Where

First instar larvae typically cause skeletonisation of leaves, feeding on the outer layer of the underside of leaves, whilst later instars feed throughout the leaf and can consume entire leaves. More mature larvae also burrow into plants causing both feeding damage as well depositing faeces that encourage fungal and bacterial growth.

Susceptible plant species

Mamestra brassicae attacks a wide range of cultivated plants, including brassicas, onions, potatoes, beans and peas.

Crops Affected by Mamestra Brassicae

Mamestra brassicae attacks a wide range of cultivated plants, including:

• Brassicas
• Onion
• Potato
• Beans
• Peas

Nemasys^®C

Nemasys^® C is based on the beneficial nematodes Steinernema carpocapsae and provides control of Mamestra brassicae in a wide range of crops.

Nemasys^® C contains nematodes in their vigorously infective juvenile stage. Once applied these nematodes seek out and control the caterpillar (larvae) of Mamestra brassicae. It can also be applied to control a range of other caterpillar pests, including Spodoptera spp., Duponchelia fovealis, Chrysodeixis chalcites, codling moth and oriental fruit moth, as well as shore fly and large pine weevil.