A parasitic species of ant from Japan is the first ever found to have done away with both males and female workers – instead, every individual is a queen that tries to take over the nests of other species.

Typically, ant colonies consist of a queen, female workers and short-lived males that die after mating.

For more than 40 years, researchers have suspected that the rare parasitic ant Temnothorax kinomurai only produces queens, but until now there has been no definitive proof.

Young queens of this parasitic species take over the nests of a related species, Temnothorax makora, killing the host queen and some workers by stinging them. They then reproduce asexually, producing cloned offspring in a process called parthenogenesis, which is rare in ants but common among some other insects. The T. makora workers are duped into helping raise the young T. kinomurai queens.

at the University of Regensburg, Germany, and his colleagues collected six colonies with T. kinomurai queens and reared them in artificial nest boxes in the lab. From these colonies, they were able to breed and raise 43 queen offspring in the lab. Inspection of their genitalia confirmed that there were no males.

These 43 queens were then given the opportunity to take over colonies of T. makora. Seven queens survived and succeeded in their coup attempts. They produced another 57 offspring, which were again confirmed to be all female queens.

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“They exhibit an entirely new form of social organisation, adding another exciting dimension to the already rich and varied world of ants,” says Heinze.

Invading colonies of other species is a risky strategy, as shown by the high failure rate of queens seen in this study. But if all your offspring are queens, you have more chances to start new reproductive colonies.

“If parthenogenesis evolves due to random mutation, as in T. kinomurai, queens can produce 100 daughters, which do not need to mate – hence, there are 100 queens that try to found a new colony,” says Heinze. “Obviously, the success of parthenogenetic queens is higher than that of sexual queens.

“This species may be considered the final step in the evolution of social parasitism, highlighting the enormous flexibility in the life histories of social insects,” he says.

A species of fungus-eating orchid has an ingenious self-pollinating method. The secret lies in the orchid’s mysterious finger-like appendage.

“I knew there had to be more to it than just an odd-looking quirk,” says at Kobe University in Japan.

Suetsugu had long been fascinated by the Stigmatodactylus sikokianus orchid because it lives in shady Japanese forests and feeds on soil fungi throughout its life, rather than relying on photosynthesis. The orchid also has a little finger-like appendage under its stigma, the sticky part that receives pollen during mating.

To investigate the appendage’s purpose, Suetsugu observed the flower out in the wild, set up pollination experiments in the laboratory and tracked changes in the orchid’s flower structure with fluorescence microscopy.

He noticed that if no insects visited the orchid to pollinate it, the flower started wilting. As it drooped, the finger-like appendage gradually moved towards the stigma, bringing pollen into contact with the sticky receptor.

The appendage thus acts “like a bridge”, says Suetsugu, transferring the orchid’s pollen in a self-pollination trick, but only as a last resort. The wilting mechanism allows a plant to hold out for a pollinator but acts as a fail-safe, ensuring it can still reproduce even if an insect never arrives. The discovery “underscores how nature can come up with really creative solutions to common problems”, says Suetsugu.

The next step would be removing the appendage completely to see how much of a difference it makes in pollination timing and efficiency, says at the Australian Tropical Herbarium.

While this appears to be the first time such a self-pollinating trick has been formally documented, Nargar notes that observations from the early 1990s suggest two other closely related orchid species also use their unusual appendages to self-pollinate.

Decreasing the diversity and abundance of gut microbes in male mice increases their offspring’s risk of low birth weight, stunted growth and premature death. This suggests that a father’s gut microbiome may impact infant health.

Plenty of research has established a link between microbes in mothers and infants, yet little is known about the impact of paternal gut health.

So at the European Molecular Biology Laboratory in Rome and his colleagues treated 28 male mice with antibiotics, which decreased the abundance of gut microbes in the animals by 10-fold and shifted their balance of microbial species.

The rodents – along with another 12 male mice that had stopped the antibiotic treatment two months earlier and 26 control mice not given antibiotics at all – then mated with females. Together the groups produced more than 400 offspring.

Pups from mice with impaired gut microbiomes had a variety of health issues not found in those whose fathers had not taken antibiotics or stopped the medication weeks before conception. They had significantly lower birth weights and were 2.5 times more likely to have severely stunted growth at 2 weeks old. Roughly 17 per cent of these pups died within three months, while only 5 per cent of those fathered by the control-group mice did.

How the gut microbiome exerts these effects is unclear. But further experiments did uncover some clues. For instance, mice treated with antibiotics had smaller testes and lower sperm counts than those that never took the medication. They also had different levels of certain hormones that influence reproductive health, such as leptin and testosterone, as well as differences in small molecules that regulate gene expression in sperm.

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Mice impregnated by these animals also had changes to their placenta – namely, it couldn’t supply the fetus with enough nutrients.

“This paper represents a significant leap forward in our understanding of the intricate relationship between gut and reproductive health,” says at Rutgers University in New Jersey. It is the first time research has shown disruptions to the paternal gut microbiome may impact male reproductive health, sperm quality and infant health, she says.

It also indicates that paternal health may be important for pregnancy outcomes, since placental changes are related to pregnancy complications like preeclampsia in humans, says Hackett. But this is merely speculation, since research in mice does not necessarily apply to humans, he adds.