INSECT COLUMN
Large cabbage white butterfly
Figure 1: Egg mass of the large cabbage white butterfly. Source: https://candide.com/ZA/insects/ eaabf98455d9bdfef9c454fdb2e744bb
(Lepidoptera: Pieridae) Large cabbage white butterfly is native in Europe, where it is widely distributed. It is also found in Asia, North Africa, Europe and South Africa. The first recognition of the large cabbage white butterfly in South Africa was reported in 1994 in the Western Cape. They are migratory insects, which is the reason why they are widely distributed. They are found in open habitats that include agricultural land, parks and gardens, especially where there are brassicas. Brassicaceae (cabbage family) is the primary host of the large cabbage white butterfly. Other host plants include mustard and as well as wild hosts.
Figure 3: Final larval instar of the large cabbage white butterfly. https://commons.wikimedia.org/wiki/ File:Pieris_brassicae_(caterpillar).jpg
Figure 2: The wingless stage of potato aphid on tomato. https://candide.com/ZA/insects/ eaabf98455d9bdfef9c454fdb2e744bb
Figure 4: Pupa of the large cabbage white butterfly.
Nozibusiso Maphumulo
https://www.cabi.org/isc/ datasheet/41157#toPictures
IPM-PROGRAM, NORTH-WEST UNIVERSITY https://www.cabi.org/isc/ datasheet/41157#toPictures
Large cabbage white butterfly classification: Class: Insecta (insects) Order: Lepidoptera (moths and butterflies) Family: Pieridae Genus: Pieris Species: brassicae
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ggs of the large cabbage white butterfly are bright yellow in colour and have a bottle-like shape. They are 1,4 mm high and ribbed vertically. Their colour changes to bright orange prior to hatching. Neonate larvae are yellow with shiny black heads. The colour changes to yellowish-green with yellow lines that runs through the length of the body after their first moulting. The back and sides of the larvae have numerous hair-topped tubercles (nodules), which makes the larva to have a rugose texture. Mature larvae are 45 mm long, with an olive-green colour. Their dorsal view is more greyish and have a noticeable yellow dorsal line, with dorsolateral black spots and squares on either sides. Fine, hair-bearing tubercles, most of which are black in colour, covers the entire body of the mature larvae. They have a bluish-grey head with black spots. Pupae have a length of 20 mm. Non-diapausing pupae are pale green, while the diapausing ones are greyish-white in colour and are marked with black and yellow dots. Their ventral surface is flattened. They have a lateral ridge on either sides. Their head is pointed forward with a similar ridge that extends from head up over the head, thorax and abdomen. It has numerous blunt spikes on the abdomen. Pupae can be found on walls, fencing, tree-trunks and stones, or under roofs and branches where it is attached to the substrate by a silken belt and pad. The final colour is similar to the substrate. Adult butterflies are 55 - 70 mm, females are larger than the males. The wings of both sexes are shiny white on the upper sides,
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Figure 5: Adult male (left), and adult female (right) of the large cabbage white butterfly.
with a noticeable black tip on the forewing. The female has a larger black tip with a pair of black spots. The undersides of both sets of wings are pale yellow dusted with grey. In females, the black spots of the forewings also appear on the undersides. The head, thorax and abdomen are black with grey hair-like scales. Adult female lays eggs uprightly (Fig. 1) in clusters of 40 - 100 on the underside of the leaves of brassicas. Neonate larvae emerge within 7 - 14 days. There are five larval instars. Larval stage takes 26 - 29 days before they pupate. Fully grown larvae leave their host plants to find a place for pupation. Pupation takes 10-15 days, then adult butterflies emerge. There are 2 to 3 generations per year. Neonate larvae starts feeding immediately after they emerge. They feed in groups whereas the mature larvae feed individually. Feeding damage leaves holes on the foliage of brassicas. Cabbage white butterfly can be controlled biologically using various parasitic wasps and flies that predate on it. Garden wildlife such as reptiles, mammals and birds also prey on the large cabbage white butterfly. Cabbages can be covered using butterfly-proof netting to prevent egg-laying on the plants. Crushing egg-shells is also another method of control against the large cabbage white butterfly. Other control methods include diatomaceous earth and wood shavings. Attracting natural predators using refuge spots such as native grasses and wildflowers can also help in controlling the large cabbage white butterfly. It can also be controlled through chemical control. Enquiries: mashimanenozi03@gmail.com
VEGETABLES & FRUIT | MARCH • APRIL 2022
