Reader Mark Sturtevant, whose arthropod photos always shine, sent three pictures with extensive biological detail THAT YOU WILL READ. First, remember that aphids are in the insect order Hemiptera, or “true bugs”; Greg posted yesterday about a hemipteran imported with some furniture from Europe. By now, from just looking at “Readers’ Wildlife,” you should have learned at least ten orders of insects (Hemiptera, Diptera, Hymenoptera, Coleoptera, Lepidoptera, Orthoptera, etc. Mark’s notes are indented:
I have a lot of pictures and interesting tales from one fabulous summer of macrophotography. Enough that I can do themes, so today the theme is aphids (part I).
I knew that aphids were rather interesting little plant suckers with an odd life cycle and all, but once I starting photographing them and looking up info to identify species, I began to stumble upon some very bizarre “aphid phacts”. So here is what I know so far. First, many species of aphids are all females during much of the summer, and these give live birth of young that are made asexually. Winged females begin to appear as things begin to get crowded, as seen here in this colony of red aphids (possibly Uroleucon sp.) that were on on sunflower. The winged aphid in this group is filled with pale blobs, and according to info that I found these are the developing babies that are visible through her transparent skin. Among my many goals in macrophotography is to try to get highly magnified pictures of such aphids to see if I can make out the eyes and legs of the babies inside, and to photograph a live birth.
Next is a group of yellow aphids (I suspect Aphis nerii) on milkweed. Different aphid species tend to have one bright color or another. It is now known that the source of these colors are from carotenoids that they make, which is a photosynthetic pigment normally found in plants. It turns out that aphids have genes for making carotenoids, and they possibly got the genes from horizontal gene transfer from their plant hosts. The function of the pigments in aphids is not known, but one speculation is they are for camouflage (some of their predators cannot see the colors that they employ). Another speculation is that the pigments help aphids make more ATP. This is the role of carotenoids in plants, since there they add to the light reactions of photosynthesis and a product from the light reactions is ATP (carbohydrates are made in a separate, coupled reaction). Although this is certainly what I would call an extraordinary claim, there is circumstantial (but not ‘extraordinary’) evidence for light reactions in these insects because aphids with carotenoids make more ATP than those that lack it, and more ATP is made when pigmented aphids are exposed to light. Here is an article about this if anyone is interested.
Finally, there are numerous insects that associate with aphids. They of course include friends and foes, a subject of another set of pictures that I would like to send one day, but other aphid groupies are just there for the sugary plant sap that aphids leave behind once they move on. That is probably the story with this wasp feeding on the aphid drippings on milkweed. I thought this wasp would be a species of yellow jacket, but it turns out that it is the European paper wasp (Polistes dominula) which has been introduced to the U.S. and is now greatly expanding its range here.
The reason for all the aphid drippings of course is that aphids live on a sugary diet of plant sap, and they need to expel excess water from this diet. This brings me to my final aphid phun phact which is that they have cells packed with bacteria that produce amino acids from this restricted diet. The aphids of course benefit from these bacterial endosymbionts.
And some lagniappe from reader darrelle—a lovely bird:
I was cleaning up my Google+ picture folder when I came across this picture of a Tricolored Heron, Egretta tricolor, that caught my eye so I thought I’d send it to you. I like the lighting and the droplets of water thrown off by the feet. The picture was taken about a year ago by my daughter, Brianna, early one morning while we were exploring a wild life reserve that is part of the Indian River Lagoon. The camera was a Nikon D3200 with a Nikkor 55-200 mm zoom lens.
Click to enlarge; the full detail is best shown when it’s bigger:
Best wildlife “picture”. Fly The W!
http://www.squier-talk.com/data/attachments/44/44681-68ad5836d89cde1a82737cdbcbdcae85.jpg
Lovely pics! Not only are aphids amazing, they are also the origin of our word ‘reproduction’, as in ‘sexual reproduction’ or ‘human reproduction’. If you think about it, when we have children, we do NOT ‘reproduce’ ourselves – our offspring are not copies of ourselves, which is what ‘reproduction’ means, and initially meant, when it was applied in the 18th century by Reaumur to aphids, after the discovery that they could reproduce without males. How the word got distorted to its more general, and strictly incorrect meaning, is one for the historians…. – MC
As you say the OED has it in this sense in English from translations of French
“1713 tr. P. Poiret Divine Oeconomy VI. i. 21 The Fecundity of Creatures, as we consider in it barely the Reproduction of themselves, is a Property in them never to be lost, without needing God’s continual Concourse.
1749 tr. J. Offray de la Mettrie Man a Machine 35 At fourteen or fifteen years of age, he scarce has a notion of the great pleasures that will attend him in the reproduction of his species.
1780 W. Smellie tr. Buffon Nat. Hist. Gen. & Particular II. 16 Without limiting our research to the generation of man, or of any particular animal, let us contemplate the general phaenomena of reproduction.”
I remember at school we had a terminal that gave us occasional access to A Computer (!) at Norwich City College, circa summer 1976, & a friend created a program based on info I had found about how fecund the un-mated females are & predicting how many descendants she could have in one year. The number is forgotten by me but was BIG. That summer was hot a& dry in the UK as many in their 50s & over will recall, & we had a plague of aphids when there were so many that it was staggering. Of course when you consider the biomass compared with even one human, I suppose that was not as big as all that…
It is often said that ‘aphids are born pregnant’. It may be that this claim is not really true, or at least not really special among animals.
The info I have says that aphids develop as eggs in the female body, and if they are to be born asexually they are simply not fertilized but develop, from the egg, to the 1st nymphal instar in the mothers’ body.
So if they start as eggs then I would say they are not born pregnant, nor are they really weird in this area (except for the parthenogensis bit).
Many female animals are born with all of their eggs, presumably like the aphids. Mammals rely on fertilization of eggs and before that eggs must complete meiosis cell divisions to reduce their chromosome number by 1/2. Remarkably, in mammals all eggs initiate meiosis before they are born, only completing meiosis during the proceedings of ovulation and fertilization. So if you are a female mammal (about 1/2 of you are), then all the eggs you will ever have were present before you were born, and they were already preparing for reproduction by starting meiosis.
Excellent photos! This aphid post is a great illustration of how photography (or painting or drawing)focuses our attention on hidden aspects of nature, and opens up new worlds to us. Thanks!
The aphid carotenoid genes come from fungi, not green plants.
I did not know that! Thank you! My sources did not mention the source, and so I naturally assumed plants.
Could the yellow color of aphids on milkweeds be aposematic? Monarch Butterflies’ larvae are supposed to eat only milkweed leaves and to take up toxic cardiac glycosides from them. Could the aphids take up glycosides from milkweed sap?
Maybe not. Their mouthparts are pretty good at tapping into the phloem vessels, which I think lacks the toxic sap. In any case, plenty of aphid species are brightly colored and they feed on harmless plants. And the ones on milkweed are preyed upon and parasitized (as I can show in part II).