Common Insect Pests of Crucifer Crops and their management

Crucifer crops, belonging to family Brassicaceae, such as cabbage, broccoli, cauliflower, kale, and mustard greens are one of the important vegetable crops worldwide. The production of these crops is challenged by several biotic and abiotic factors. Among biotic factors insect pests are one of the critical factors causing huge losses in different parts of world.   Here's a comprehensive overview of some common crucifer insect pests and their management strategies.

Cabbage Aphid (Brevicoryne brassicae)

Description

Cabbage aphids are small, pear-shaped insects that feed on the sap of crucifer plants. They can be green, yellow, or black in colour and often cluster on the undersides of leaves. Aphid produce honey dew which makes the plant sticky and favour the growth of sooty mould with black coating thus hindering the photosynthesis and plant growth. Both, adult and nymphs suck sap from plant causing loss of vigour, as a result of which plants remain stunted resulting in poor head formation. 

Management:

• Install yellow sticky traps @ 12 no./ha to monitor “macropterus” adult.
• Encourage natural predators such as ladybugs, lacewings, and parasitic wasps.
• Apply insecticidal soaps or oils to suffocate aphids.
•  Introduce biological controls like Aphidius colemani, a parasitic wasp that targets aphids.

Diamondback Moth (Plutella xylostella)

Description

Diamondback moths are small, greyish-brown moths, where caterpillar is pale yellowish green. Characteristic three diamond shaped yellowish white spots is visible when adult moth joins both the forewings. Young larvae feed by scrapping leaf tissue causing typical white patches on the underside of leaves. Grown up larvae bite holes in the leaves, creating large ragged holes. They are highly destructive and can cause severe damage, especially in warm climates.

Management

• Remove and destroy all debris and stubbles after harvest of crop.
• Pheromone traps @ 12/ha also controls the pest.
• Grow mustard as trap crop at 2:1 ratio (cabbage: mustard) to attract diamondback moth (DBM) for oviposition at least 10 days ahead of planting of main crop. 
• Introduce natural enemies such as parasitic wasps (Diadegma semiclausm and Cotesia plutellae) which are very effective.
• Apply Bacillus thuringiensis (Bt) or spinosad, microbial insecticides that target caterpillars.

Cabbage head borer (Hellula undalis)

Description

Adult moth is slender, pale yellowish-brown, having grey wavy lines on the forewings, whereas caterpillar are pale whitish brown with 4-5 pinkish-brown longitudinal stripes. Females of the moths lays pinkish oval eggs singly bit more often in cluster, generally under surface of the leaves. The caterpillar webs together the foliage and feeds on the leaves. It also feeds on the flower heads in cabbage and cauliflower.

Management

• Handpick larvae from plants.
• Apply Bt or spinosad to target caterpillars specifically.
• Introduce natural enemies such as parasitic wasps and predatory beetles.

Cabbage leaf Webber (Crocidolomia binotalis)

Description

Adult is small with light brownish forewings, where caterpillar is red headed with brown longitudinal stripes and rows of tubercles on the body. Caterpillar webs together the foliage and feeds on leaves. It also feeds on flowers and pods in the case of mustard and flower heads in cabbage and cauliflower

Management

• Remove and destroy the webbed leaves with caterpillar within.
• Cotesia crocidolomiae is very effective larval parasitoid.
• Spray malathion 50 EC @ 0.1% to control the pest. 

Cabbage butterfly (Pieris brassicae)

Description

Adult butterfly is having snow white forewings with black distal margin. Hindwings is pure white with black apical spots. Caterpillar is velvety green which are gregarious initially but disperse as they grow. Caterpillar cause damage by skeletonising leaves and bore into heads of cabbage and cauliflower. 

Management

• Collect and destroy caterpillar in the early stage of attack.
• Cotesia glomeratus is very effective larval parasitoid against this pest.
• Spray insecticides like quinalphos 25 EC  1000 ml. 

Cabbage Root Maggot (Delia radicum)

Description

The larvae of cabbage root maggots feed on the roots of crucifer plants, causing wilting and reduced plant vigor. Adult flies lay eggs near the base of plants, and the larvae burrow into the soil to feed on roots.

Management

• Use floating row covers to prevent adult flies from laying eggs near plants.
• Apply beneficial nematodes to the soil to target root maggots.
• Practice crop rotation to disrupt the life cycle of root maggots.

Tobacco caterpillar (Spodopera litura)

Description

Adult moth is stout, browncoloured, with wavy white markings on the forewings. Females lays eggs in masses which are covered with brown hairs. The caterpillar is blackish grey to dark green with dark longitudinal bands on the side of the body. Young larvae (neonates) scrap the green matter from the leaves. Late instar feed voraciously on tender leaves and fresh growth. 

Management

• Plough the soil to expose and kill the pupae.
• Flooding the field to drive out the hibernating larvae is very effective.
• Pheromone traps (Pherodin SL) @ 15/ha is also very effective.
• Spray Sl NPV @ 1.5 X 1012 POBs/ ha + 2.5 Kg crude sugar + 0.1 % teepol.

Conclusion

Insect pests are major constraints in successful cultivation of cabbage that includes diamondback moth (Plutella xylostella) (DBM), aphids (Brevicornae brassicae and Myzus persicae), stem borer (Hellula undalis) and Spodoptera litura. The feeding damage by the pests spoils the quality of the head and renders it unfit for human consumption. Novel insecticides like spinetoram can be incorporated into IPM programs and need to be used alternatively or sequentially in insecticide resistance management strategies. Integrated Pest Management (IPM), which combines multiple control methods judiciously, is often the most effective approach for managing crucifer insect pests while minimizing environmental impact and maintaining crop health. Regular monitoring of fields for pest presence and implementing control measures as needed is essential for successful pest management. Additionally, cultural practices such as crop rotation, proper watering, and timely fertilization can help improve plant health and resilience to pest pressure.

Contributors

• Niraj Guleria, Mountain Agricultural Research and Extension Station, CSKHPKV, Salooni, Chamba 176320, India
• Suresh M Nebapure, Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi-110012, India 
• Rajna S, Division of Entomology, ICAR-Indian Agricultural Research Institute, New Delhi-110012, India 
• Pratap A. Divekar, Division of Crop Protection, ICAR-Indian Institute of Vegetable Research, Varanasi-221305, India