APHIDS are the small and soft bodied insect that can move in almost any zone.Aphids prefer the bottoms of leaves rather than the top. There nymphs look very similar to adults.
They move very slowly and it is the easiest way to control its natality rate.Because Aphids are the destructive pest, they are the fear of a large number of growers, as yellowing, mottled leaves, stunted growth, curling of leaves, browning, low yields and even death of many plants may occur due to its attack.
Many of the other aphids found in greenhouse production carry one or more viruses.As the plants grow, eventually the aphids move to above-ground plant parts.where they are exposed to foliar insecticides and biocontrols.
Aphid consist of about 4000 species of plant-specific-parasite.They are about 4 milimeter in size, they have bulbous abdomen and Aphids are present in variety of different colours like white, black, brown, gray, yellow, light green, or even pink.
Every specie has its specific habitat(aphids live in colonies, they will move to other plants when their host plant is dying or overpopulated.) and habits.
For example,bean aphids, cabbage aphids, potato aphids, green peach aphids, melon aphids, woolly apple aphids, the cotton aphid (Aphis gossypii) prefers cotton and the black peach aphid (Brachcaudus persicae) prefers peach and so on.
- Monoecious Aphid: Are those aphid that feed on a particular plant.
- Heteroecious Aphid: Are those aphid that feed on different species of plants.These aphid reproduce sexually atleast once in their lifespan and start their cycle when the winter eggs hatch on the primary host.Annual weeds, shrubs or trees are its primary host.
Reproduction Patterns of Aphids
The Aphid life cycle is between 1 week and 40 days.Parthenogenesis occur in Aphid, where female aphids give birth to live female nymphs, by passing the egg stage, spring and summer season is favourite for its reproduction.
Female can give birth to 12 offspring per day in warmer climates. These offspring mature and can bear offspring themselves in about a week or so, and the cycle keeps going and going. Generation upon generation can be produced each year by the tiny aphids.
This rapid reproduction is kept in check by natural predators, environmental factors, and chemical controls.In spring the hatching occur on the plant (as primary host).The aphid that born from the winter eggs are all the females.
Female aphids are born during spring and summer season.Lifespan of female is 25 days and during its life span it can produce upto 80 new aphid.Asexual reproduction occurs during spring and summer.Females fertilized by the males lay winter eggs on the plant where they are, closing the cycle.
DAMAGE AND SYMPTOMS OF APHID ATTACK:
Aphid mostly remove the phloem sap for food as a result weakens the plant and cause a metabolic imbalance, leaf loss and curling or twisting of leaves occur. Leaf loss affects the quantity and quality of the final harvest.potato plant damaged by the potato virus Y which is trasmitted by aphids. Potato virus Y(PVY) is one of the best virus affecting solanaceae (tomato, potato, sweet pepper etc.)
Aphid are mostly characterized by a stylus which means a kind of syringe needle that is used to pierce and suck the sap from the plant. Cornicles or siphunculi are also present which are the couple of tubes in the back of aphid from which the animal excrete honeydew called cornicle wax,
Through which sooty mold fungus growup, the leaves and branches become black in colour that cause hinderence in photosynthesis.Aphids may transmit viruses between plants, and also attract other insects that prey on them, such as ladybugs.Presence of sticky substance on the plant surface may also indicate the attack of aphid.
RELATIONSHIP BETWEEN APHID AND ANTS
There may be an increase in the ant population surrounding an infested plant. Since the aphids’ honeydew is high in sugar, it attracts the ants to the plant. The ants feed off the honeydew secretions and actually protect the aphids from predators.
Aphid usually suck the cell sap from the plant and feed on those parts of the plant which is rich in sugars, minerals and other elements.aphids love to hide underside of leaves.
HOW TO COMBAT WINGED APHIDS
Winged aphids are very dangerous for crops, they destroy plants much faster than regular aphids. sticky yellow traps can be used in the air to protect from its attack and place water traps on the ground. The water traps consist of a yellow plate containing two fingers of soapy water. Barrier crops can also be used.
This method involves using plants that are not susceptible to viruses transmitted by aphids to protect the primary crop from these vectors.When the aphid reaches the barrier plant and tests its sap, many viral particles attached to the stylus and mouth parts are detached.
When the same aphid goes from the plant barrier to the primary crop it will be virus-free. In this way, the barrier crops have a cleansing effect on the non-persistent viruses that aphids can carry.
- Treating the plants anywhere between 5 to 7 days is ideal because it helps to eliminate any new aphids.
- spraying of cold water should be done on the leaves.
- In case of large aphid attack, plants should be dust with flour. It constipates the pests.
- Neem oil(Safer® Brand Neem Oil), insecticidal soaps(Safer® Brand Insecticidal Soap),and horticultural oils are effective against aphids.
- By mixing of mild solution of water and a few drops of dish soap. This mixture should be applied after every 2-3 days for 2 weeks..
- Diatomaceous earth(DE) is a non-toxic, organic material that will kill aphids.But it is recommended that when flowers are in bloom don’t use (DE) because it can also affect the pollinators too.
- Check your trap plants regularly to keep aphid populations from jumping to your valued plants.
- Insecticidal soaps often don’t damage plants, but be careful when spraying new growth or blooms as they can be extra sensitive.though using a formula like Safer® Brand Insecticidal Soap though it is not harmful for beneficial insects
- Isopropyl alcohol (also called isopropanol or rubbing alcohol) works fine and is easy to find, but be sure it doesn’t have additives.
BIOLOGICAL CONTROL: Lady beetles, lacewings and parasitic wasps, will feed on aphid, the aphid populations can be controlled from the start, without hurting your plants.
Parasitic wasps lay their eggs inside the aphid’s body eventually killing the host insect. Pesticides that remain in the soil, reducing the number of beneficial microorganisms and eliminating nutrients like phosphorus and nitrogen, which plants need to thrive.
CAUTION: Try to avoid the use of pesticide because it is not only toxic for harmfull insects but may have detrimental effects other for birds, beneficial insects and other animals.pesticide can also be harmful for humans, as irritation to skin or eyes might be occur and some other problems like cancer and reproductive issues may also happen.
Some have residual effect, and they don’t breakdown when its raining and as a result enter the water supply like rivers and streams and become dangerous for the other aquatic animals.
Before applying test a small area first, and apply in morning or evening. Before applying more,watch the plant for a few days for any adverse reactions . Plants can be sensitive to alcohol and soap.
Authors: Arzlan Abbas and Amir Gulzar, University of Agriculture Faisalabad, Pakistan.
Corresponding Author: Arzlan Abbas