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Mustard aphid (Lipaphis erysimi) Photo: placeholder pending image-fill pass

Mustard aphid (Lipaphis erysimi)

The mustard aphid (Lipaphis erysimi Kaltenbach, Hemiptera: Aphididae) is the single most damaging pest of rapeseed-mustard in northern India. It is responsible for 35-70 percent yield losses in unprotected crops in Rajasthan, Haryana, Punjab, Uttar Pradesh and Madhya Pradesh, and is the principal reason the recommended package of practices for mustard treats vegetative-to-flowering-stage scouting as mandatory.

Identification and symptoms

Adults are small (1.5-2.5 mm), soft-bodied, pear-shaped insects that are yellowish-green to greyish-green with a powdery wax coat. Nymphs resemble adults but are smaller and wingless. Colonies build up on the underside of leaves, tender shoots, inflorescences and developing pods. Heavy infestation causes leaf curling, stunted growth, sticky honeydew on plant parts and sooty mould. Flowering and pod-set are reduced and the crop takes on a blackish appearance from below. Severe attacks at the pod-filling stage cause shrivelled, light seed with reduced oil content.

Hosts and lifecycle

The aphid is oligophagous on Brassicaceae — Indian mustard, toria, gobhi sarson, taramira, raya, radish and cabbage. In the Indo-Gangetic plains it is anholocyclic and reproduces parthenogenetically through the rabi season. Cooler weather (15-25 deg C) with bright sunshine and low humidity favours rapid build-up; foggy, drizzly weather suppresses populations. Peak attack is recorded from the first fortnight of January to mid-February in central Indian conditions and slightly later in higher latitudes. Each adult viviparously produces 30-90 nymphs over a 10-15 day reproductive life.

Economic impact

ICAR-DRMR Bharatpur and AICRP-Rapeseed-Mustard yield-loss studies place average untreated losses at 35-58 percent, rising to 70-90 percent in late-sown crops that coincide with peak aphid phenology. Oil content reductions of 2-5 percentage points compound the loss. The economic threshold level (ETL) is 25-30 aphids per 10 cm of central twig, or visible colonies on 25 percent of plants.

Management

  • Cultural: timely sowing (mid-October to first week of November in north India) so flowering escapes the peak aphid window; balanced fertilisation avoiding excess N; intercropping with chickpea or wheat in 9:1 or 6:3 ratios suppresses aphid build-up.
  • Resistant varieties: no commercial variety is fully resistant; tolerant lines include RH-749, Pusa Mustard 27 and DRMR-150-35. See Mustard Pusa Bold.
  • Biological: conserve coccinellid predators (Coccinella septempunctata, Menochilus sexmaculatus), syrphid larvae and the parasitoid Diaeretiella rapae. Avoid spraying when natural-enemy ratios are favourable.
  • Chemical: at ETL, foliar spray of dimethoate 30 EC at 1 ml/L, imidacloprid 17.8 SL at 0.3 ml/L, thiamethoxam 25 WG at 0.2 g/L or oxydemeton-methyl 25 EC at 1 ml/L. Seed treatment with imidacloprid 70 WS at 5 g/kg gives 25-35 days of protection from sowing. Rotate insecticide groups; avoid sprays during flowering to protect pollinators.

See also: Mustard crop, Pusa Bold mustard, Mustard Alternaria blight, NMOOP oilseeds mission.

Sources

  1. Integrated Pest Management of Rapeseed-Mustard. ICAR-Directorate of Rapeseed-Mustard Research, Bharatpur.
  2. AICRP-Rapeseed-Mustard Annual Report 2023. DRMR, Bharatpur.
  3. Lipaphis erysimi datasheet. CABI Compendium.