For this ID Challenge, please identify the objects/structure in the photos below and discuss how they are related to each other. I’ll give 5 pts to anybody who correctly identifies the object/structure in each photo and another 5 pts to anyone who correctly elucidates their connection. Go!
Edit: I am looking for a family-level ID for the objects in the first photo and a genus-level ID for the plant bearing the structure in the second photo to get full credit. Answers will be held in moderation until the answers are revealed to give all a chance to play.
© Ted C. MacRae 2014
16 thoughts on “ID Challenge #22”
First structures are butterfly eggs. Look like a Pierid. Second structure is a false egg that certain plants produce to discourage female butterflies from ovipositing as females will not oviposit on plants upon which other eggs have been laid. True of Falcate Orange-tips and others.
Heliconius eggs and plant structures in Passiflora which imitate the Heliconius eggs, to suppress over-oviposition.
If my first comment did not make it clear, the false egg is produced by the host plant of the butterfly that laid the eggs in the first photo. I am pretty sure they are the eggs of a Pierid, as I said.
I think eggs of Nymphalidae….but the second image is a mystery.
Arabus for the plant genus
I will go with Nymphalidae (brush-footed butterflies) for the family of the eggs, and Passiflora (passion fruit) for the genus of the plant. I think the plant produces these structures which mimic eggs to discourage butterflies like Heliconius from ovipositing on the plant.
Nymphalid eggs (Agraulis?) on Passiflora? Drip tips that mimic eggs to avoid oviposition?
If spelling counts it is Arabis…I’m doing this off the top of my head. With a few minutes research I could get answer as I have read about this somewhere. If not Falcate Orange-tip, than Olympia Marble, West Virginia White, one of our native and declining species of Pierids…
Butterfly egg cases in the first image and imitation butterfly cases in the second, created by a would-be host plant to dissuade egg-laying.
Lepidoptera (Heliconius) for the eggs and the plant genus that bears the stipules is likely Passiflora.
The orange structures in the first image look like lepidopteran eggs. The second…could it be a fungus (rust)? The butterflies might preferentially choose to lay their eggs on a plant parasitized by the fungus in hopes that they will be mistaken for the fungus by an egg predator.
The objects in the first photo look like butterfly eggs (Nymphalidae). The second photo reminds me of the feeding pattern left by some young nymphalid larvae, which eat the tissue at the tip of a leaf so that only the midrib remains, and then perch on the midrib when at rest. I don’t think that’s what this is, though, since the tip appears smooth and slightly swollen, as well as orange (like the eggs). No idea what’s going on here…
I would say that the first structures are butterfly eggs from a species in the family Nyphalidae possibly Heliconiinae. Since they feed on passion flower, I will say the plant is Passiflora. The structure in the second picture is a false egg produced by the plant to limit egg laying by the butterfly.
Number 1 looks like the eggs of Pieris rapae/brassicae to me. The fact it’s two odd eggs rather than one big clump points towards the former. As to picture 2 I have no idea whatsoever. It doesn’t look like the egg laying apparatus of a butterfly, neither does it look like a wasps ovipositor to lay eggs inside the eggs in picture 1. So to summarise, I’m stumped!
Pierid eggs? The plant’s discolorations look like they could mimic the eggs. This could be to try to minimize the competition for resources between larvae (if the discolorations were actually eggs), so the female pierids won’t lay their eggs on plants with the discolorations.
Time to reveal the answers to the quiz. The objects in the first photo are butterfly eggs, specifically of the genus Heliconia (family Nymphalidae, subfamily Heliconiinae), while the object in the second photo is a modified stipule of a plant in the genus Passiflora. The resemblance between the two is the result of a marvelous example of herbivore-mediated evolution. Heliconia butterflies feed exclusively on species of Passiflora, in many cases only a single species. Intra- and interspecific competition between the butterflies can be intense, with caterpillars actually eating other eggs and larvae that they encounter on their host plants. As a result, female butterflies avoid laying their eggs on plants on which eggs have already been layed. Obviously, larval feeding has a negative impact on the host plants, and the butterfly’s oviposition behavior has resulted in some Passiflora species in the independent evolution of modified structures on their stems or leaves that resemble Heliconia eggs, with the result that the presence of these structures dissuades female butterflies from laying eggs on the plant. In this example (seen in the research greenhouses at the Brackenridge Field Laboratory in Austin, Texas during the ESA meetings there last November), the modified structure is a stipule that matches the egg, if not perfectly in shape, in its bright yellow color.
So, on to the points. Full credit for the ID portion of the quiz requires the terms “eggs”, “Nymphalidae”, “Passiflora”, “mimic” (or equivalent), and “stipule” (1 pt each). Full credit for the connection between the two must include references to inhibited oviposition (2 pts) and contributing behaviors for it’s evolution (up to 3 pts). With this in mind, I have awarded points as follows:
– Adrian Ruicanescu – 6 pts
– Ben Coulter – 6 pts
– Matt C. – 6 pts
– Mike Baker – 6 pts
– Ian Wright – 5 pts
– Harry Zirlin – 4 pts
– tjhedlun – 4 pts
– Anonymous – 2 pts
– Charley Eiseman – 2 pts
– Carol Gracie – 1 pt
– Laurie Knight (@_lauriek) – 1 pt
Nobody earned full points, but four people got 6 pts. By virtue of being first, Adrian Ruicanescu snags the challenge win, and Ben Coulter and Matt C. round out the podium. Everybody who played earned points that will help their standings in the current BitB Challenge session. Ben Coulter continues to lead in that overall competition, but 2nd and 3rd places are still very much up for grabs!