What are Citrus Aphids?
There are generally five species of aphids considered to be commercially dangerous. Two of them are specifically damaging to citrus namely Toxoptera citricidus (Brown citrus aphid) & Toxoptera auranti (Black Citrus Aphid). Citrus aphids are small insects which have a piercing-sucking mouthpart that they use to feed upon leaves, tender shoots & flowers.
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| Brown Citrus Aphids | Black Citrus Aphids |
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| Life Cycle of Citrus Aphids(20 – 40 Days) | |
Life cycle-
The lifespan of aphid species is only about 20 to 40 days. Their high reproductive rate compensates for the short lifespan and maintains their population. Reproduction involves asexual as well as sexual reproduction.
- Their life cycle begins with the hatching of eggs on a host plant at the beginning of spring.
- All the eggs that hatch produce aphid larvae.
- All of them get developed into wingless females that depend the host plant for nourishment.
Asexual Reproduction-
- After continuous feeding for 7 to 10 days, the females mature and reproduce asexually, through a process called cyclic parthenogenesis.
- The wingless matured females give birth to about five to ten clones, every day.
- These are exact replicas of the original wingless aphids.
- These clones too mature fast, feed, and create more clones.
- Ultimately, a swarm is created on the host plant, through this exponential reproduction.
- Once they have devoured a host plant, they develop wings and migrate to a host plant of another species by drifting on the wind, as they can’t fly.
- The asexual reproduction or cloning cycle continues on the new host and this continues throughout summer.
Sexual Reproduction-
- When fall approaches, as the temperatures drop, some of the female aphids get transformed into males and sexual reproduction begins.
- The females lay eggs that hatch on plants to complete the cycle and start it again.
- The incubation period for eggs is 7-8 days in most species.
- In some warmer climates, sexual reproduction may never occur and they continue reproducing asexually.
How does it damage the plant?
- The nymph and the adult suck the sap from the leaves and new shoots and adhere in clusters to the underside of young citrus leaves and new shoots.
- They sometime attack blossoms and young fruits.
- Once the tissue becomes unfavorable for feeding, the colonies produce alate adults (Having wings or winglike attachments) for dispersal, and the remaining nymphs either die or leave the trees searching for other branches or trees. The dispersal of nymphs from one tree to another by crawling a distance is mostly up to 8m-12m.
Symptoms-
- The affected leaves results in curling up, deformation, yellowing and crinkling and stunted growth in affected shoots.
- They also secrete a honey dew like substance which enhances the growth of sooty-mould, which affect the normal functioning of plants.
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Source- https://www.agric.wa.gov.au/citrus/aphids-citrus
Prevailing month-
Aphids are more active during September – February.
Management-
| Cultural Practices | Biological Control | Chemical Control |
| Removal of water sprouts.Proper cleaning should be followed in orchard to reduce the pest infestation. | Aphids are attacked by many generalist predators include hoverfly larvae (syrphids), ladybird beetles and lacewing larvae. Use of Verticillium leccani @ 5 ml per liter twice at fortnightly interval during flush season. | Foliar Spray of following Agro-chemical can control pest infestation —Dimethoate 30% EC @ 2ml per liter water.Imidacloprid 17.8 SL @ 1ml per liter water.Profenophos 50% EC @ 2ml per liter water. Spraying Neem Seed Kernel Extraction @ 3-5 ml per liter of water may also reduce the pest infestation. |
Source
Book – High density cultivation of Nagpur Mandarin by ICAR – CCRI, (IARI)
