Aphids are one of the few creatures on earth that don’t need sex to produce babies. So how do aphids reproduce asexually? And if they can do it, why then do they sometimes do it sexually too? Let’s find out
Aphids are a type of insect that belongs to the Aphidoidea superfamily. These insects extract sap from plants, and you might also know them as greenflies or blackflies.
The reproduction process of aphids tends to be rapid and quite complex at the same time. They are one of the few creatures on earth that can alternate between sexual and asexual reproduction.
Scientists call this parthenogenesis, and the only others who can do this include the wasp, bees, ants, and a few small invertebrates.
To make it even more complex, they only alternate between these methods in certain conditions. For example, fall is the season for sexual reproduction, whereas spring is the season for asexual reproduction.
Aphid Life Cycle
The life cycle of aphids is known as holocyclic, which is science-speak for the fact that they are sometimes sexual, and sometimes asexual.
During spring, the aphid eggs hatch, and the baby aphids are born only as females. They grow and become juvenile aphids (nymphs). Before adulthood, they molt four times before adulthood.
These adult aphids are “stem mothers” that give birth to another generation of female aphids. All through summer, they produce wingless female nymphs.
In late summer, the last lot of stem mothers produce male aphids for a very specific purpose – the male help to fertilize eggs that aphids lay in preparation for winter.
You see, adult aphids cannot survive harsh winters – but their eggs can! That’s why it is important to have male aphids and lay eggs – it ensures that the next generation of aphids overwinters as eggs and survives the harsh weather.
The final generation of aphids lay eggs, which overwinter and hatch in the spring, thus ensuring the continuity of the species.
Do Aphids Lay Eggs?
Yes, aphids do lay eggs, but mostly because eggs can overwinter. Its not the main way they reproduce – that they do it through cloning (which we cover next).
Their tiny and elliptical eggs are easy to find if you know where to look for them. Look on the underside of leaves or on plant stems of their host plants. This is where female aphids lay eggs and stick them for safekeeping.
The eggs are also of many colors – sometimes you will find black ones, and other times you might find yellow or orange eggs.
Cloning
Scientists might be trying their best to master cloning to produce a liver or heart for humans, but these bugs have it all figured out already – Aphids can clone themselves!
Cloning is a part of the life cycle of aphids, and aphids create nymph clones of themselves most of the year instead of laying eggs like most of the insect world.
This process of creating little mini-me aphids is called “parthenogenesis“. Interestingly, the clones are not genetically identical, unlike the impression you might have gotten from movies.
Female aphids have XX chromosomes. Male aphids only have the X chromosome and no Y chromosome. This is why male aphids are said to have XO chromosomes.
The aphid clones have XX chromosomes, just like their mama’s. As you might have noticed – they don’t need anything from the male aphid to be born (unlike in humans).
Female aphids create entire generations by cloning during the summer and spring without any need for a male.
Interestingly, cloning is much quicker than laying eggs, so aphids can recreate a whole colony very quickly when they are at it.
But what happens when there are too many aphids on one host? We get to the next amazing superpower of these bugs – flying!
Winged Aphids
Aphids live on host plants, on which their entire life cycle happens, but they can also change host plants sometimes.
Aphids migrate from a host when the plant has too many of them and no longer has the nutrition to support all. But unlike fleas or springtails, they cannot jump on to another plant. So what is an aphid to do?
This is when some of the newer generations start being born with wings. These winged females fly to a different host plant and then colonize it.
However, once their purpose is solved, they stop making more winged offspring, and the nymphs that come afterwards are again wingless. Researchers call this “dimorphism” and attribute it to both genetic and environmental conditions.
Winged aphids may be sexual females, but they don’t reproduce as fast as the wingless ones (perhaps it takes more time to clone if you are flying around).
This means that other insects can colonize the host plant before they can. Wingless females can reproduce both asexually and sexually.
Sexual Reproduction
In the fall, like all creatures, aphids start to prepare for winter. But unlike ants who collect food for the winter, aphids decide to go one step ahead – they prepare to lay eggs.
Female aphids start to create babies without one chromosome (the males). These males take a while to mature, but once they are ready, the male aphids start to mate with females.
The females then lay aphid eggs and lay them on the host plants.
Now, we mentioned earlier that male aphids have XO chromosomes instead of XY chromosomes.
This means that even those aphids born out of sexual reproduction cannot be males; they will always be females.
At this point, you might wonder why male aphids are at all necessary when the females can clone themselves.
Well, it is necessary because winters can be harsh, and adult aphids do not survive in the cold for too long. However, their eggs can survive the cold.
Sexual reproduction produces fertilized eggs and ensures that a new generation of aphids can be born after the winter. These eggs stay dormant during winter and only hatch when it is warm enough, continuing the life cycle.
Frequently Asked Questions
How do aphids reproduce both sexually and asexually?
All aphid species can reproduce both sexually and asexually in different seasons. Sexual reproduction occurs in the fall.
But during most of the year, over spring and summer, aphids reproduce asexually, creating clones. Sexual reproduction is required to produce eggs which can survive the winter, unlike the aphids themselves.
Is an aphid asexual?
Aphids are among the few organisms that can reproduce both sexually and asexually, in response to changes in season.
That’s why aphids reproduce rapidly in spring and summer but you can hardly see their infestations during the winter. During the summers, they clone themselves (which is quicker), but during the winter, they produce eggs instead.
How do insects reproduce asexually?
Aphids reproduce asexually by cloning. All female aphids can clone with XX chromosomes. This process of cloning gives rise to multiple asexual generations.
It is only towards the end of the reproductive period that male aphid are born. These are simply aphids that are missing an X chromosome.
How often do aphids reproduce?
Aphids reproduce throughout the year, except for very cold months. Females lay aphid eggs for most warmer periods and can give birth to as many as twelve clones per day!
This is why aphid infestations spread so rapidly in gardens and plantations during spring and summer. But during winters, you would find them completely missing.
Wrap Up
Aphids are very common, and one reason is their amazingly adaptable reproduction process. The grain aphid, green peach aphid, and pea aphid are among some of the most common pests in America.
If you come across aphids, don’t treat them just as pests. These tiny bugs have one of the most interesting of life cycles. We hope this article helps you understand them better. Thank you for reading!
