Male Moth's Sperm Protects Females

May 10, 1999

ITHACA, N.Y. -- An enduring nuptial gift is included in every sperm package from a male rattlebox moth (Utetheisa ornatrix)to his freshly mated female: a potent, plant-derived chemical that protects her for life against predatory spiders, biologists at Cornell University have discovered.

The first (but almost certainly, not the only) example of a sexually transmitted chemical defense to benefit a female animal is reported in the current (May 11, 1999) Proceedings of the National Academy of Sciences by Cornell biologists Andrés González, Carmen Rossini, Maria Eisner and Thomas Eisner. The protective chemical, pyrrolizidine alkaloids (PAs) that the adult male obtains by eating rattlebox plants (Crotalaria mucronata) while in the larval stage, reaches every part of the female's body within minutes after mating, the biologists say. It also protects her eggs.

"Only a human bridegroom would buy life insurance for his bride. This classy moth gives a gift she can really use -- a life assurance policy, if you will -- that keeps paying off every time her life is in danger," says Thomas Eisner, the Schurman Professor of Chemical Ecology at Cornell. During courtship, Eisner adds, the female rattlebox moth has a way of sensing which suitor offers the best chemical defense, and she chooses accordingly.

Native to central Florida, U. ornatrix earned another common name, the ornate moth, for its distinctive coloration, an intricate pattern of flamingo pink, black and white that adorns the inch-long adults. "They are one of the few moths to fly during daylight," Rossini says. "They literally flaunt their brilliant colors, as if to say: 'You should know from my pattern that I am distasteful.' "

Spiders that don't know the color code are quick to find out that the moth is inedible. One taste of the chemical-laden moth is enough to make a spider cut loose its erstwhile prey from the web, and the moth escapes unharmed. The Cornell biologists repeatedly tested moths on wolf spiders and orb-weaving spiders.

Every moth with PAs survived its close encounter with the spiders, while moths without the defensive chemical in their bodies were killed or eaten. That is because they were raised on a laboratory diet of pinto beans, which do not have PAs, or because the females mated with males that could not offer the nuptial gift of PAs.

Until the Cornell study, only Utetheisa's eggs were known to benefit from a male's nuptial gift. The grisly experiment with spiders was performed to prove that the female profits, as well.

"It didn't seem right that the female could not benefit from the male's alkaloidal gift," González says, detailing the contents of the spermatophore, as the insect sperm package is known. (See "Ornatrix Tricks" fact sheet, attached.) Weighing more than 10 percent of the male moth's body mass, the spermatophore contains enough sperm to fertilize hundreds of U. ornatrix eggs, nutrients to help the female produce numerous healthy eggs and PAs, now known to protect the female as well as her eggs, González says. "It makes sense that the male should contribute to the female's defense. She is, after all, the recipient of the sperm."

"Of course the defensive alkaloids also protect the male," Rossini says, "and they have a secondary benefit for him during courtship. A chemical derivative of PA is released into the air from two brushes on the male's abdomen during the courtship dance, as a way of telling the female how much alkaloid he can offer.' To initiate the courtship dance and attract males from a distance, the female releases her own sex pheromone, which is not related to PAs, Rossini notes.

"With this finding, we have added one more item to that very short list, 'What Are Males Good For?' " Thomas Eisner quips. "They evidently donate more than sperm."

He credits his wife, Maria Eisner, a research associate in the Section of Neurobiology and Behavior at Cornell, with carrying out the outdoor moth-spider tests. Also a wife-and-husband team, Rossini and González are graduate students in that department. The study appears in the National Academy of Sciences (NAS) journal as "Sexually Transmitted Chemical Defense in a Moth (Utetheisa ornatrix)." It was supported in part by a National Institutes of Health grant and by Johnson & Johnson Fellowships in Chemical Ecology to Rossini and González.

Related World Wide Web sites: The following sites provide additional information on this news release. Some might not be part of the Cornell University community, and Cornell has no control over their content or availability.

-- PNAS journal online:

-- Cornell Institute for Research in Chemical Ecology: http://www.cfe.cornell.e du/circe/aboutcirce.html

Ornatrix Tricks

Five Fun Facts about a Bad-tasting Moth

(Source: Cornell University Section of Neurobiology and Behavior)

Cornell University

Related Sperm Articles from Brightsurf:

Nut consumption causes changes in sperm DNA function
Researchers have evaluated for the first time the effect of a short/middle-term consumption of a mixture of tree nuts (almonds, hazelnuts and walnuts) on sperm DNA methylation patterns in healthy individuals reporting eating a Western-style diet.

Collecting sperm from Covid-19 patients
How does Covid-19 affect sperm and thus the next generation┬┤s immune system?

Paleontology -- The oldest known sperm cells
An international team of paleontologists has discovered giant sperm cells in a 100-million year-old female ostracod preserved in a sample of amber.

Research captures how human sperm swim in 3D
Using state-of-the-art 3D microscopy and mathematics, Dr Hermes Gadêlha from the University of Bristol, Dr Gabriel Corkidi and Dr Alberto Darszon from the Universidad Nacional Autonoma de Mexico, have reconstructed the movement of the sperm tail in 3D with high-precision.

Overweight and obesity are associated with a low sperm quality
Researchers from the Rovira i Virgili University in collaboration with researchers from the University of Utah have carried out a systematic review and meta-analysis evaluating the association between adiposity (normal weight, overweight, obesity, and low weight) and the sperm quality.

Diet has rapid effects on sperm quality
Sperm are influenced by diet, and the effects arise rapidly.

Sperm may offer the uterus a 'secret handshake'
Why does it take 200 million sperm to fertilize a single egg?

Long duration of sperm freezing makes no difference to live birth rates in large sperm bank study
Despite a time limit imposed in many countries on the freeze-storage of sperm, a new study from China has found that the long-term cryopreservation of semen in a sperm bank does not affect future clinical outcomes.

An important function of non-nucleated sperm
Some animals form characteristic infertile spermatozoa called parasperm, which differ in size and shape compared to fertile sperm produced by single males.

DNA of sperm taken from testicles of infertile men 'as good as sperm from fertile men'
Scientists have found that sperm DNA from the testicles of many infertile men is as good as that of ejaculated sperm of fertile men.

Read More: Sperm News and Sperm Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to