[HELICONIUS] Heliconius antiaphrodisiac doesn't work?

[Catalina Estrada]

Hi!

I had the chance of reading Matt Cornish's thesis about antiaphrodisiacs 
in Heliconius (the PDF is available in the website at the end of Jim’s 
e-mail). Sadly he did not publish his work as he has some good results 
there. I think he did a good set of experiments and in what it seems 
good greenhouse conditions (good pollen, host plant, cage size). 
Although, his results are interesting, I don't agree with all of his 
conclusions.

This is why.

One of the problems is that he assumed that removing the stink clubs 
from a female butterfly remove the ability of releasing the abdominal 
pheromone. So his males did not court differently control (intact) and 
experimental (stink removed) mated females. As far as I know these 
organs are assumed to help dispersion of the pheromone but there is 
little evidence this really happen or that they are the only part from 
where the chemicals are released. In fact, in the original morphological 
description of the gland Eltringham (1925, Transactions of the 
Entomological Society of London: 269-275) suggested that pheromone could 
also be released through the yellow gland itself. Even if humans cannot 
smell the odor of females without stink club (as Cornish said) 
biologically relevant amounts for male butterflies could still be 
released in his control females.

One point of Cornish’s results I agree with is that postmating female 
odors do not induce (pupal-mating) males sitting in pupae to leave their 
post more often than would control virgin females. However, I don’t 
think, this negate the antiaphrodisiac function of the odor, since males 
are tested with a stimulus (the odor) out of its context (courtship of 
an adult female).

I think our behavioral tests with melpomene, cydno and charithonia 
support the hypothesis that some components of the postmating odors in 
Heliconius females repel courting males. How effective they are vary a 
lot among males, and under some ecological conditions.

Hopefully we can test soon what other functions these odors have!

Cheers,

Catalina


Catalina Estrada
University of Texas at Austin
Integrative Biology
1 University station C0930
Austin TX 78712
https://webspace.utexas.edu/ec1972/www/