Capital or income breeders?

[naftaliin]

In terms of reproduction strategy many insects can be divided into capital breeders and income breeders. The first group uses energy and resources stored during the larval stage for reproduction in the adult stage and the insects of second group have less reserves and need to feed in the adult stage in order to lay eggs.

 

I´m curious about Oryctes nasicornis. I heard that this species does not feed as an adult but also there are claims that it can be seen on flowers and people that breed them feed adults too. Since mine larvae died, I can´t test it myself.

 

Can anyone elaborate on this? What is the experience among breeders? And what about other species?

[Matt]

I've not come across the terms "capital" and "income breeders" before - its that used in literature anywhere or it it your own terminology.

[naftaliin]

I found these terms in:

Walczyńska, A. 2008. Female reproductive strategy in the longhorned beetle Corymbia rubra (Coleoptera, Cerambycidae). Norw. J. Entomol. 55, 25–30.

 

Walczyńska herself cites:

Stearns, S.C. 1992. The Evolution of Life Histories. Oxford University Press, Oxford.

 

for the concept of using stored energy vs. acquired energy during reproductive period for reproduction.

[LarvaHunter]

Interesting, I'm going to look into that. I think longhorns are capital breeders, also possibly jewel beetles. It would seem Dynastes would be an income breeder?

The ones that spend a short time alive as an adult until mating would probably be capital breeder.

I would think in captivity, the adults that are offered easy food to eat, probably eat it, but if they don't need to eat as adults in the wild just means they are more interested in reproducing.

An analogy could be a pet black widow pair in captivity or a preying mantis pair, you could take out the male after they mate to spare his life, but in nature we know that they are killed by the female after mating.

[Matt]

I found these terms in:

Walczyńska, A. 2008. Female reproductive strategy in the longhorned beetle Corymbia rubra (Coleoptera, Cerambycidae). Norw. J. Entomol. 55, 25–30.

 

Walczyńska herself cites:

Stearns, S.C. 1992. The Evolution of Life Histories. Oxford University Press, Oxford.

 

for the concept of using stored energy vs. acquired energy during reproductive period for reproduction.

 

Thanks for the info.

[naftaliin]

I think longhorns are capital breeders, also possibly jewel beetles.

I don´t think it applies to all longhorns. For example the large poplar longhorn Saperda charcharias feeds of leaves and bark after emerging from pupa. But the famous Titanus giganteus has been reported not to feed as an imago indeed and have a short lifespan too. So not sure how common both strategies are..

 

Actual observations would be interesting. Has anyone noticed their insects mating and laying eggs without feeding them?

[LarvaHunter]

Soon I will be trying to breed longhorns of diff species, I will let you know the results of them without feeding the adults, as I am curious as well.

Do you know what adult jewel beetles eat? If anything.

[naftaliin]

Unfortunately I don´t have much knowledge about that group yet. I have read that they can be seen on flowers.

[LarvaHunter]

I catch different species of longhorns easily on a uv light sheet under live oak trees, between 9PM and 2-3 AM.

Recently I found a small one inside a water plant flower in the middle of a lake.

[naftaliin]

Ok I was able to contact somebody who has bred O. nasicornis grypus and he claims that this insect does not feed as an adult. He also got eggs from females without feeding them. This should mean that this Dynastes is a capital breeder. Interesting is that it also lives quite long (up to 6 months after becoming active). So even the imago longevity is not a sure indicator whether an insect is a capital breeder or an income breeder.

In theory the best way to determine if an insect is a capital breeder should be dissection. Natural selection should have caused capital breeders to not have a digestive system as adults (not viable to invest in organs that are not going to be used). So capital breeders should have no digestive system at all or have a devolved, rudimentary one that is not working.

 

From a breeding point of view O. nasicornis should be easy to keep as you only have to provide food for the larval stage.

[LarvaHunter]

I read a paper that was saying capital breeders use their body reserves and some adult insects don't even have mouthparts!

If they don't even have mouthparts then that does make me wonder about their digestive system, like what else do they not have.

[naftaliin]

I read a paper that was saying capital breeders use their body reserves and some adult insects don't even have mouthparts!

If they don't even have mouthparts then that does make me wonder about their digestive system, like what else do they not have.

 

Yes that makes sense as the mouth is really the beginning of the digestive system. And that would be a better method actually than dissection. Much easier to check for a mouth and mouthparts than cut the insect open and look for a digestive system. If I get my hands on a O. nasicornis imago, I´m going to see what it`s mouth and insides look like. It definitely has a fat bulging abdomen (lot`s of reserves there).