Sneaks bearing gifts – 5 things male insects will do for sex

 “I drive these brothers crazy,

I do it on the daily,

They treat me really nicely,

They buy me all these ices.

Dolce & Gabbana…” – Black-Eyed Peas

 

“I got my mind set on you

I got my mind set on you

But it’s gonna take money…” – George Harrison

“You could always tell what kind of a person a man thinks you are by the earrings he gives you.” – Holly Golightly

Sex has been at least partly about transactions for as long as time itself.  It is no different in the animal kingdom – and with just as much (if not more) cheating, lying and sneaking.

Do the now-dated stereotypes of the expensive girlfriend and the lavish, hopeful boyfriend stand up to facts?   Surprisingly, even now, the answer is yes: according to a recent study, statistically men actually do become bigger spenders when they are competing for a smaller pool of women, concentrating more on immediate spending instead of saving. Something in our subconscious responds to increased competition, and changes our behaviour accordingly.

As biologists we would describe money spent to secure sex as a nuptial gift. This phrase probably conjures up something to do with weddings – but in behavioural ecology, “nuptial gift” means something a male transfers to a female before or during sex (besides sperm).

Nuptial gifts in insects

In Allonemobius crickets, the females eat the males’ legs. Photo: Nick DiRienzo

Nuptial gifts in the insect world take many weird forms.  A dead insect is de rigueur.  But consider which of the following would seduce you if you were the female… would you be impressed by a male offering you part of his leg, for instance, as in some crickets?  Or perhaps, like Neopyrochroa beetles, you are irresistibly drawn to the chemically weaponized sperm that the male has made for your children to use against predators?  Surely a bit of extra nutrients in his sperm is at least partly tempting – no?  How about he throws in some antibiotics into it to make you feel better afterwards?  (For further reading on the diversity of nuptial gifts, see this review)

But just as in humans, gifts are not always what they seem.  The insect world is full of examples of nuptial gifts, but these gifts can be drugged, fake, worthless, or stolen back before the female can enjoy them. Alternatively, they can just be about getting away alive…

Bittacus male with nuptial gift. Photo: Alex Wild at Myrmecos.

5 examples of lying, cheating males bearing gifts…

1. Males steal back the gift after sex: In Bittacus scorpionflies, if there is any of the gift left uneaten after sex has finished, the male will try to steal it back from the female in order to attract other females.  This often involves a prolonged struggle.

Male Empidid fly with balloon. Photo: Mike Dunn.

2. Worthless gifts – In Hilara dance flies, the male offers the female a large, inedible, empty balloon. Other flies in this family offer prey wrapped in silk, so we think males “discovered” that females were using the size of the silk wrapping alone as a rule of thumb to choose between males. In Empis, another dance fly, males usually offer prey, but sometimes offer plant fluff instead.  Similarly male Pisaura spiders often offer bits of wood, or already-eaten food.

Female Ephipigger bushcricket eating the spermatophylax. Photo:Gerlind Lehmann

3. Cheap gifts – crickets “plug up” the female after mating with a gluey mass that the female eats before she can mate again. Sometimes she gains nutritional benefits from eating this mass, but recently it was shown that in some cases it contains only cheap forms of protein with little nutritional value, but which taste good and stimulate eating (a bit like offering to cook dinner for your date, but instead laying on 8 jumbo bags of popcorn which she has to eat before she can have another date…)

Male Pisaura spider gives a gift to a female. Photo:Trine Bilde

4. Drugged gifts – In some spiders the silk in which the male wraps the gift contains drugs that induce the female to mate (i.e. spider Rohypnol).  In crickets again, the eating stimulants in the nuptial gift hide a sinister cocktail of drugs that make the female less horny afterwards, so she is less likely to want to mate with other males.  This also happens in fruit flies, famously (to biologists!).

Pisaura male feigning death, dragged by female. Photo:Maria Albo.

5. Gifts for protection – In bell crickets, males with a gift are less likely to be beaten up by females.  Even worse – in spiders, males are at risk of being entirely eaten by females.  However, they stand less chance of being eaten if the female is already feeding. In Pisaura spiders, females usually show interest in a male’s gift but will occasionally attack the male instead, at which point he feigns death until she loses interest. When she begins eating the gift, he then “comes to life” and starts mating…

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2 thoughts on “Sneaks bearing gifts – 5 things male insects will do for sex

  1. I’m fairly sure there isn’t any known species that *always* gives fake gifts. Even the balloon flies sometimes have a piece of prey in the balloon. There are two hypotheses about why empty worthless balloons can work as a gift (unfortunately that paper above doesn’t really test between them). First is that in the time when there was always prey in the balloon, the females evolved to use the size of the *silk* as an indicator of how good the male was. Alternatively, the balloons may simply catch the females’ attention “from afar” and bigger balloons are better at catching females’ attention. This way you don’t need prey in your balloon for it to be effective at attracting females.

    But I haven’t (in my cursory searches…) seen any data on whether males are individually consistent in bringing fake gifts, or whether their choice depended on the female – that would be a great question to test!

  2. This is great! I have a question: when males give fake gifts, is it whole species that always gives fakes, or is it certain individuals that always give fakes, or do different individuals vary between giving fakes or real presents depending on the female..?

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