The cabbage moth (Mamestra brassicae) is primarily known as a pest that is responsible for severe crop damage of a wide variety of plant species. The common name, cabbage moth, is a misnomer as the species feeds on many fruits, vegetables, and crops in the genus Brassica (i.e. cabbage, broccoli, Brussels sprouts). Other notable host plants include tobacco, sunflower, and tomato, making this pest species particularly economically damaging.

The moth spans a wide geographic range encompassing the entire Palearctic region. Due to this wide geographic region and the presence of various populations globally, local adaptations have resulted in a species with high variability in life history and behavior across different populations.

Geographic range

The cabbage moth has a wide geographic distribution across parts of Europe and Asia ranging from about 30°N to 70°N in latitude.

Taxonomy

The cabbage moth, Mamestra brassicae, should not be confused with the cabbage looper (Trichoplusia ni) or the white cabbage butterfly (Pieris rapae) which share similar names but occupy different taxonomies.

Mamestra brassicae belongs to the order Lepidoptera (moths and butterflies). Within this order, the species belongs to the clade Ditrysia, which contains 98% of the Lepidoptera species and indicates that the female has two separate openings for mating and laying eggs. The species belongs to the family Noctuidae, the second largest family in Lepidoptera. Within this family, the cabbage moth falls within the subfamily Hadeninae. The genus Mamestra is home to many pest species and has a global distribution.

Technical description and variation

B. brassicae L. (= albicolon Stph., nec Hbn., ochracea Tutt) Forewing grey-brown varied with fuscous: lines pale, dark-edged; orbicular stigma rounded, reniform large, white-spotted, or filled in with white; hindwing brownish, with a paler mark near end of vein 2. -

The insect varies in opposite directions; - ab. albidilinea Haw.

is a blackish form with the reniform stigma and submarginal line white, occurring occasionally in Europe as well as in Britain; — scotochroma Rob., a local German form, is melanic, with both wings blackish, much like albidilinea, but without the white submarginal line; — unicolor Tutt has all the markings, dark and light, more or less lost in the fuscous suffusion, the reniform edged only with whitish; — on the other hand andalusica Stgr. from Spain (? = straminea Failla-Ted., from Sicily and Italy) is pale grey- brown with a faint ochreous flush, darker grey in female, with all markings obscured except the 3 stigmata which are strikingly pale, with partial blackish outline, especially on their lower edge, the claviform sometimes grey; — decolorata Stgr. from Issykkul and other localities in Central Asia is pale greyish brown, with the stigmata as in andalusica, but with the markings, especially the submarginal ones, not obsolete; — canescens Moore from Yarkand, which I have not seen, is, judging from the figure, very close to, if not identical with, decolorata which it antedates by 10 years. Larva polyphagous, varying in ground colour from green to brown and blackish, with broad pale spiracular line; a dorsal hump on segment 11.

Life history

thumb|200px|Adult cabbage moth

The life history is highly variable depending on the location of the population. Some populations are able to fit two to three generations within one calendar year. Other populations, in less favorable climates, may have only one generation in a given year. Diapause is this species' most variable life stage, lasting anywhere from 80 days to six months if needed over the winter.

Caterpillars

thumb|140px|left|Figs 3, 3a, 3b, 3c, 3d larva after last moult

The caterpillar progresses through six instars of development. In the first instar, the caterpillar has a light green body with three pairs of legs along the thorax and an anal appendage at the end of the abdomen. The caterpillars remain relatively the same in color until the fourth instar, in which the dorsal region darkens. The dorsal region now appears brown while the ventral region turns yellow. There is some variability in coloring at this stage. There is also a dark stripe that appears to run down the length of the caterpillar with light yellow stripes flanking the sides. The head is a copper color. At the sixth and final instar, the head remains copper and the body and develop a dorsal hump. The total time for this larval development is four to six weeks and the final body length ranges from . dark back marks, various white back and side spots; dark 'tier tread marks' type patches; big, shiny, brownish or coppery colored eyes,

  • Grey above, pick side stripe and tan bottom.
  • Like a peace red-brown earth
  • Tan above, white and then yellow stripe and pink underside.
  • Green-grey above, yellow stripe and light green below
  • Grey green with a dark green back stripe
  • Black above, yellow side stripe and light yellow green below The pattern of mating is as follows:

Calling position

The females initiated the mating sequence. She does so by calling for the male which entails positioning her antennae forward, raising her wings horizontally, and flapping her wings quickly. If there is no male response to this call, the female relocates and repeats the calling behavior until she is able to successfully attract a male mate.

Another study was conducted to understand the influence of host plant damage on the host-finding behavior of female moths. Surprisingly, female moths of this species tend to preferentially select for damaged host plants for oviposition. This finding is rather surprising given that it would be expected that females would select for undamaged plants to help her offspring avoid resource competition with whatever species had already fed on the plant. However, researchers hypothesize that this may be due to the release of volatiles, to which females are attracted.

Migration

A study of M. brassicae in East Asia demonstrated that the species is migratory. Researchers found that annual migration across a 40–60 km strait. Data also indicates that females migrate more than males, with a significantly higher proportion of captures being female compared to the population sex ratio during the months of May to September. Coupled with the finding that these migratory females had high ovarian development and mating rate during this time, researchers concluded that this migration promoted female sexual maturation prior to mating. This would allow females to mate and oviposit in their newly arrived upon territories.

References

Citations

  • Chinery, Michael Collins Guide to the Insects of Britain and Western Europe 1986 (Reprinted 1991)
  • Skinner, Bernard The Colour Identification Guide to Moths of the British Isles 1984
  • Taxonomy
  • Lepiforum e.V.
  • De Vlinderstichting
  • https://www.mothidentification.com/cabbage-moth.htm