Aphids (Family: Aphididae) are among the most destructive insect pests of cultivated plants worldwide. These soft-bodied, sap-sucking insects possess highly specialized piercing–sucking mouthparts that enable them to extract phloem sap from host plants with ease. They typically colonize the undersides of tender leaves and young shoots but can infest any above-ground plant tissue at any growth stage.
Despite their fragile appearance and limited independent flight capability, aphids disperse over long distances by exploiting low-level jet winds. Of the thousands of known species, approximately 250 are considered economically important crop pests.
Host Range
Aphids exhibit a broad host range, infesting numerous agricultural and horticultural crops, including:
Vegetables: kale, cabbage, tomato
Fruit crops: passion fruit, guava
Ornamentals: roses
Legumes: beans, green grams
Herbs: basil
Cucurbits: watermelon
Life Cycle
Aphid reproduction is predominantly parthenogenetic, allowing females to produce live nymphs without mating. In species that lay eggs, these typically hatch into wingless females that soon begin parthenogenetic reproduction.
Key reproductive characteristics:
Newly born nymphs reach reproductive maturity in about 7 days.
A single female can produce up to 5 offspring per day for approximately 30 days.
Winged morphs (alates) develop when colonies become overcrowded or host conditions deteriorate, facilitating dispersal.
This rapid reproductive capacity enables populations to build up quickly and cause significant crop damage.
Identification
Aphids are small, often difficult to detect without close inspection. Their distinguishing features include:
Pear-shaped bodies ranging in colour from white, yellow, green, pink, brown, grey, to black
Long antennae and two characteristic abdominal projections called cornicles
Wingless adults are common, but winged forms appear under stress or crowding
Many species produce a waxy or woolly coating
Nymphs resemble adults but are smaller
Aphids typically occur in dense colonies, though individuals may also be found scattered.
Feeding and Damage
Both nymphs and adults feed on plant sap, targeting leaves, stems, buds, flowers, and developing fruits. Feeding causes:
Leaf distortion – curling, cupping, stunting, yellowing
Growth suppression due to nutrient loss
Wilting under severe infestations
Deformed flowers and fruit
Formation of galls in some species
Virus transmission, a major cause of crop losses
Aphids excrete honeydew, a sugary waste that promotes the growth of sooty mold, reducing photosynthesis and attracting ants that protect aphid colonies.
Management and Control
Due to their rapid multiplication, aphids must be controlled before populations begin to reproduce for effective suppression.
Chemical Control
Highly effective insecticides with contact and systemic activity include:
Group 1
BILLIONAIRE 500 WP – 5g/20 L
EMERALD 200SL – 10 ml/20 L
KINGCODE ELITE 50EC – 10 ml/20 L
LEXUS 247SC – 8 ml/20 L
Group 2
LOYALTY 700WDG – 5 g/20 L
PENTAGON 50EC – 10 ml/20 L
PRESENTO 200SP – 5 g/20 L
PROFILE 440EC – 30 ml/20 L
Important Notes:
Alternate insecticides within the season to delay resistance development.
Always mix insecticides with INTEGRA (3 ml/20 L) to enhance spreading, sticking, and penetration.
To manage sooty mold, apply JAMBOCLEAN (60 ml/20 L).
Non-Chemical Control Options
Biological control: conservation or introduction of natural predators such as lady beetles, lacewings, and parasitic wasps
Companion planting: e.g., garlic and chives repel aphids when interplanted with lettuce or peas
Crop rotation with non-host species
Weed management to eliminate alternative hosts
Field sanitation to reduce pest reservoirs
Use of resistant varieties where available