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Acrolepiopsis assectella (Leek Moth) - Fact Sheet

Background

The Leek Moth (Acrolepiopsis assectella) larva is specialized to feed on the leaves of various plants belonging to the genus Allium. In Asia and the U.K the Leek Moth is considered a minor pest. However, in continental Europe it has caused considerable damage, particularly to leeks. It was first detected in Canada in 1993 in the National Capital Region (Ottawa-Hull) where a local population is now established (J.-F. Landry, in L. Handfield.1997. Liste des Lepidopteres du Quebec et du Labrador. Fabreries Supplement 7.).

Hosts

A variety of species in the Lily family, Liliaceae serve as hosts. Leek (Allium porrum) is the preferred host. Other hosts include, onion (Allium cepa var. cepa), chives (Allium schoenoprasum), garlic (Allium sativum) and Shallot (Allium cepa var. aggregatum).

Distribution

Biology

Leek moth adults overwinter in plant debris emerging in April when the temperature reaches 9.5°C. Mating taking place 24 hours after emergence. Females are generally considered to be monogamous and live for about 23 days. The adults are nocturnal with flights and mating restricted to the hours of darkness, flights rarely occurs during the day. On average there are three generations per year. Female moths lay eggs singly on the host, mostly on the lower leaf surface, and usually near the base of the plant. The eggs hatch in 4 to 6 days in the spring and 8 to 11 days in the fall. Solitary larvae begin mining the leaves upon hatching, only if their mines coalesce do they become gregarious. On leek, they prefer to feed on the youngest leaves, but can consume leaves more than two months old. They bore through the folded leaves to the centre of the plant, causing a series of pinholes and feeding on the inner leaves. On onion, they feed inside the hollow leaves. Occasionally, larvae may attack reproductive parts of the host plant but usually avoid the flowers. The flowers contain a saponin compound that inhibits the growth of the larvae. There are five larval instars, which last about 11-23 days. Pupation occurs mainly on the food plant but can also occur on the soil or neighbouring plants, or among plant debris. In the field, the pupal stage lasts about three weeks, or it may overwinter.

Detection & Identification

Symptoms

Identification

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adult
Fig. 1

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egg
Fig. 2

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larva
Fig. 3

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Frass
Fig. 4

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damage to flower
Fig. 5

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damage to flower
Fig. 6

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damage to leaves
Fig. 7

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damage to leaves
Fig. 8

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inspection
Fig. 9

Text: Plant Health Surveillance Unit
Photo Credits: Fig. 1-2 Institut National de la Recherche Agronomique, 147, rue de l'Université, 75338 Paris Cedex 07 France, Fig. 3-9 Dr. J-F. Landry, Eastern Cereal and Oilseeds Research Centre, Agriculture and Agri-Food Canada, Ottawa.

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