The Very Strange Science of Aphids
Aphids suck - literally. Aphids have modified mouths that enable them to pierce and suck the juicy nectar from plants, measuring just over two millimeters, and they are EVERYWHERE- even in your garden or house right now. Aphids are part of the insect group hemiptera, a group of bugs that have hardened outer wings, with membranous wings underneath (the same group as ladybugs). Up close, aphids can resemble tiny muscle cars with tailpipes. There are over 4000 varieties of aphids, and most of them are considered to be pests. But there is much more going on with these litter critters than meets the eye.
Aphids are herbivores and rely solely on the nectar of plants to supplement their diet. But there is much more sugar in the plant juices than protein. As a result, in order for them to ingest enough nutrients (besides sugar), they have to eat a LOT of plant sap- often times more than they can digest, resulting in there excrement's being made up of almost entirely sugar- which ants love. In fact, ants love these sweet-treat producing bugs so much that they will adopt aphids and farm them to provide a consistent source of food. Ants have evolved to have chemicals on their feet to subdue and tranquilize aphids, making sure to keep them close-by as a ready food source. Ants have also been known to bite off the aphids' wings to prevent them from escaping- a more hostile tactic. However, it isn't all that bad for the creepy crawlies.
[Image source: Stewart Butterfield]
Aphids sweet excrement and predominant body composition containing mostly sugar makes them delicious bite-sized snacks to a large variety of pests, such as the ladybug which can consume up to 60 aphids a DAY. Ants that farm aphids offer protection and make sure their "cattle" are kept well fed, allowing the critters a chance to reproduce during their short lives of a month or two - without getting eaten (a considerably beneficial friendship). These conditions create a mutualistic bond in which both species can prosper; the ants get their daily dew supply , and the aphids get protection from predators, allowing a chance to breed and reproduce.
[Image Source: Bramblejungle]
Aphids strange relationship with ants and unique dung are not all that makes them so different. Most aphids you see are most likely female, some species of aphids do not even have a male counterpart. In other species, males may only be created during certain parts of the year. Aphids are parthenogenesis, or asexual reproducers meaning that females do not require fertilization in order to give birth- they can do all the work by themselves if no males are present by cloning themselves. The life cycle goes much quicker if you skip a step. Another strange thing about aphids is that they do not lay eggs, the eggs generally hatch inside the female, giving birth to an active nymph. More so than that, the nymphs are ready to lay eggs in just 10 days! This breeding process is so fast that nymphs are often born pregnant, so in just 10 days these newborns will already be giving birth- allowing three generations to be born- in just one month! This means that a pregnant aphid could be carrying her kids, and grandkids! In fact, aphids reproduce so quickly, they could reproduce 600 billion descendants in one season (ouch)! Aphids can reproduce at an exponential rate, without the need for males. They survive solely due to their speedy breeding process, providing strength in numbers.
[Image Source: Systemlayers]
These impressive little critters lay hardy eggs that survive the harsh winters to be born again in the spring and start the sugar-pooping, rapid-breading, nectar-munching cycle all over again. It is no wonder that these bugs have survived for so long with their long companionship with ants and rather inventive survival techniques. You keep doing you, aphids, because you're doing great.
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Professor Gretchen Benedix is an astrogeologist and cosmic mineralogist who studies meteorites and figures the forming stages of the solar system.