Aphids are soft-bodied insects in the family Aphididae, and are among the most destructive insect pests on cultivated plants. They use their piercing sucking mouthparts to feed on plant sap.
They are usually found in colonies on the undersides of tender terminal growth and can attack any above-ground part of the plant, at any growth stage.
Although they look so plump and dumpy that they are unable to fly far, aphids can travel to long distances with the help of low-level jet winds.
About 250 aphid species are serious pests.
Aphids attack a wide range of plants causing significant damages. These include the following;
- Vegetables e.g. kale, cabbage, tomato
- Fruit trees e.g. passion, guava
- Ornamentals e.g. roses
- Legumes e.g. beans, green grams
- Herbs e.g. Basil
- Cucurbits e.g. watermelon,
Reproduction is entirely or nearly entirely parthenogenetic, whereby, the adult female aphids give birth directly to smaller aphids, instead of first laying eggs.
If eggs are laid, they hatch producing wingless female aphids which after some time begin parthenogenetically reproducing.
Newly born aphids are capable of reproducing within about a week and can produce up to 5 offsprings per day for up to 30 days.
Aphids are small (often invisible to the naked eye). The nymphs resemble the adults.
They have varied colours, depending on the species, ranging from white, black, brown, gray, yellow, light green, or even pink!
They have pear-shaped bodies with long antennae and most species have two short tubes projecting from their hind end.
Some species have a waxy or woolly coating.
Adults are wingless, but most species develop a winged form especially when populations become crowded, to enable them travel to other plants when conditions become unfavourable.
Aphids usually feed in large groups, although they can also be seen singly or in small numbers.
Feeding & Damage
The nymphs and adults feed on plant sap, attacking leaves, stems, buds, flowers and fruit, depending on species. Most aphids like the succulent or new growth.
Infested leaves misshapen, curl, stunt and turn yellow leaves. Heavily-infested leaves can wilt due to excessive sap removal.
Flowers and fruit become malformed, distorted or deformed when infested with aphids.
Some aphid species cause galls to form on roots or leaves.
Aphids also transmit viruses to certain plants.
The sticky sugary substance (honeydew produced by the insects as waste as they feed can attract other insects like ants or facilitate the development of a fungal growth called sooty mold, causing the attacked parts appear black. This reduces photosynthetic surface, especially if on the leaves.
Management & Control
Aphids multiply very fast and should therefore be controlled before they start reproducing, for effectiveness.
There are several methods which can be employed in managing and/or controlling aphids. These include the following;
This involves the use of insecticides. The following insecticides have both contact and systemic properties and therefore very effective against aphids.[vc_column width=”1/2″]
- AMAZING TOP 100WDG 5g/20l
- BACIGUARD 16WDG 15g/20l
- EMERALD 200SL 10ml/20l
- EMERALD GOLD 700WDG 5g/20l
- EPITOME ELITE 500SP 10g/20l
- KINGCODE ELITE 50EC 10ml/20l
- LEXUS 247SC 8ml/20l
- LOYALTY 700WDG 5g/20l
- PENTAGON 50EC 10ml/20l
- PRESENTO 200SP 5g/20l
- PROFILE 440EC 30ml/20l
- SINOPHATE 750SP 20g/20l
- TAURUS 500SP 10g/20l
- Although aphids are easily controlled using insecticides, it is advisable to alternate various chemicals within a crop season. This prevents resistance build up by the pest against either of the insecticides.
- Insecticides should be mixed with INTEGRA 3ml/20l whenever spraying. This is a sticker, spreader and penetrant which enhances the effectiveness of the chemical.
- JAMBO CLEAN 100ml/20l is used to clear the sooty mold.
Other control methods
- Use of predators, e.g. lady beetles, lacewings, parasitic wasps, etc., which will feed on aphids.
- Companion planting, for instance, garlic and chives repel aphids when planted near peas or lettuce.
- Crop rotation with non-host plants
- Proper weed control
- Maintenance of field hygiene/ sanitation
- Planting resistant varieties