By Kathleen Prudic, Oregon State University

An iconic North American migration is in jeopardy. The monarch butterfly migrates back and forth from Mexico to Canada every year, its orange and black sails peppering blue skies. In the past 20 years, almost one billion monarchs have gone missing across North America. That’s about 1,000 acres, or 600 soccer fields of dead butterflies laid side by side. This abrupt drop in monarch numbers – estimated to be between 65% – 75% of the population – is causing scientists, policy makers and conversationalists in Canada, Mexico and United States to sound the alarm and take steps to reverse the decline.

Monarchs are small organisms but mighty continental travelers with only one menu item for their hungry caterpillars: milkweed. All monarch larvae feed exclusively on members of the genus Asclepius which are common in disturbed, open habitat. Milkweeds are not viable forage for vertebrates as they contain heart toxins similar to ones used in digoxin heart medication.

In the past, milkweed plants grew in areas where vast herds of buffalo traveled, churning up the Midwest soil as they moved; instead, today one sees mainly signs of human activity, such as fallow fields, roadsides and the banks of irrigation channels.

Unlike bird migrations, in which the same individual goes back and forth to breeding and wintering grounds, the monarch completes its eastern North American migration over multiple generations. Adult monarchs leave their overwintering grounds in the high elevation of central Mexico in late winter, fly north to Texas and lay eggs on emerging milkweed.

These larvae develop into butterflies which fly north to the Midwest, laying more eggs along the way. The next generation of monarchs goes further north or stays locally if milkweeds are still available. Come fall after successive waves of northern movement, eastern monarch butterflies can be found from Ontario to Illinois and from Minnesota to Kansas, more or less.

The fall generation then take to the skies when the environmental cues are right, riding the predominant air currents south towards Mexico. Monarchs who fed on milkweed as caterpillars in the Corn Belt are the most likely to return to Mexico. Upon arriving, they snuggle in for a long winters roost with millions of other monarchs on the boughs of pine trees until early spring.

Why the rapid decline?

Many environmental factors affect eastern monarch populations and migration success, such as land use change, climate change, weather dynamics and disease. Of particular concern is the increased use of herbicides in association with herbicide-tolerant (HT) crops, a type of genetically modified organism. The expansion of HT corn into the Midwest over the past 10 years has been correlated with decreases in the number of monarch butterflies.

HT modified crops can withstand the presence of glysophosate chemicals, unlike their unmodified neighbors which wither and die when the herbicide is applied. Around two million pounds – the equivalent weight of about 100 African elephants – of glysophosate herbicides are used in the United States between agricultural, residential and industrial needs every year.

The application of these herbicides destroys habitat in another way for the monarchs. Corn fields have truly become monocultures as a consequence of these new farming techniques; they are devoid of weeds, such as milkweed, that help support a more biologically diverse community.

Because of the intricacies of monarch migration, conservation is complicated. Coordinating three federal governments and numerous local officials is no small task. Mexico has been successful in recent years conserving land used by monarch overwintering populations, but their efforts are still threatened by dynamic weather changes and disease at these sites.

Eastern Canada is monitoring land use change and engaging citizen scientists to report monarch observations via the internet. The US Fish and Wildlife Service launched an initiative this month to revitalize the milkweed population along the Interstate 35 migration route.

Citizen scientists call to action

These coordinated federal programs, while broad in scope, are still not enough to ensure eastern monarch survival. However, there are a number of non-governmental organizations and citizen-run programs contributing to help monarch migration.

The National Wildlife Federation is offering milkweed seeds for anyone interested in planting them in their gardens, cities and suburbs. Demand for milkweed seeds will probably exceed supply in the near future. Concerned citizens could also donate to organizations with a track record for insect conservation such as the Xerces Society, write government officials in support of monarch conservation efforts, support farmers in developing better herbicide use strategies, and reduce or eliminate herbicide and pesticide usage in their own garden and local businesses.

For adventurous spirits and nature lovers, there are options for joining citizen science ventures where you report when and where you see monarchs. Journey North, iNaturalist, and eButterfly, where I am co-director, all offer ways citizens can collect high-quality data useful for scientific discovery. Recreational nature watching is on the rise, too, allowing people to enjoy the natural world while helping science and conservation. Tracking monarch butterflies – and planting milkweed – are ways that non-scientists can help restore what some people call the king of butterflies.

This article was originally published on The Conversation.
Read the original article.

By Leif Richardson, University of Vermont

Search for information on ‘self-medication,’ and you’ll likely find descriptions of the myriad ways that we humans use drugs to solve problems. In fact, the consumption of biologically active molecules — many of which come from plants — to change our bodies and minds seems a quintessentially human trait.

But plants feature prominently in the diets of many animals too. A growing body of research suggests some animals may derive medicinal benefit from plant chemistry, and perhaps even seek out these chemicals when sick. Chimpanzees eat certain leaves that have parasite-killing properties. Pregnant elephants have been observed eating plant material from trees that humans use to induce labor. You may have even seen your pet dog or cat eat grass – which provides them no nutrition – in what’s believed to be an effort to self-treat nausea by triggering vomiting.

In my research, I’ve looked at how bumble bees are affected by these kinds of biologically active compounds. With colleagues, I’ve found that certain plant chemicals naturally present in nectar and pollen can benefit bees infected with pathogens. Bees may even change their foraging behavior when infected so as to maximize collection of these chemicals. Could naturally occurring plant chemicals in flowers be part of a solution to the worrying declines of wild and managed bees?

Why do plants make these chemicals?

On top of the compounds plants make to carry out the ‘primary’ tasks of photosynthesis, growth and reproduction, plants also synthesize so-called secondary metabolite compounds. These molecules have many purposes, but chief among them is defense. These chemicals render leaves and other tissues unpalatable or toxic to herbivores that would otherwise chomp away.

Many studies of coevolution center on plant-herbivore interactions mediated by plant chemistry. An ‘arms race’ between plants and herbivores has played out over long time scales, with the herbivores adapting to tolerate and even specialize in toxic plants, while plants appear to have evolved novel toxins to stay ahead of their consumers.

Herbivores may experience benefits, costs or a combination of both when they consume plant secondary metabolites. For example, monarch butterfly larvae are specialized herbivores of milkweeds, which contain toxic steroids called cardenolides. While monarchs selectively concentrate cardenolides in their own bodies as defense against predators such as birds, they may also suffer slowed growth rate and increased risk of mortality as a consequence of exposure to these toxic compounds.

Interestingly, secondary metabolites are not only found in leaves. They’re also present in tissues whose apparent function is to attract rather than repel – including fruits and flowers. For example, it has long been known that floral nectar commonly contains secondary metabolites, including non-protein amino acids, alkaloids, phenolics, glycosides and terpenoids. Yet little is known of how or whether these chemicals affect pollinators such as bees.

Could secondary metabolites influence plants’ interactions with pollinators, just as they affect interactions with herbivorous consumers of leaf tissue? Similar to other herbivores, could bees also benefit by consuming these plant compounds? Could secondary metabolite consumption help bees cope with the parasites and pathogens implicated in declines of wild and managed bees?

Plant compounds decrease parasites in bees

With colleagues in the labs of Rebecca Irwin at Dartmouth College and Lynn Adler at University of Massachusetts, Amherst, I investigated these questions in a new study. We found that a structurally diverse array of plant secondary metabolite compounds found in floral nectar can reduce parasite load in bumble bees.

In a lab setting, we infected the common eastern bumble bee (Bombus impatiens) with a protozoan gut parasite, Crithidia bombi, which is known to reduce bumble bee longevity and reproductive success. Then we fed the bees daily either a control sucrose-only nectar diet or one containing one of eight secondary metabolite compounds that naturally occur in the nectar of plants visited by bumble bees in the wild.

After one week, we counted parasite cells in bee guts. Overall, a diet containing secondary metabolites strongly reduced a bee’s disease load. Half the compounds had a statistically significant effect on their own. The compound with the strongest effect was the tobacco alkaloid anabasine, which reduced parasite load by more than 80%; other compounds that protected bees from parasites included another tobacco alkaloid, nicotine, the terpenoid thymol, found in nectar of basswood trees, and catalpol, an iridoid glycoside found in nectar of turtlehead, a wetland plant of eastern North America.

We expected that bees might also incur costs when they consumed these compounds. But we found that none of the chemicals had an effect on bee longevity. Anabasine, the compound with the strongest anti-parasite benefit, imposed a reproductive cost, increasing the number of days necessary for bees to mature and lay eggs. Despite this delay, however, there were no differences in ultimate reproductive output in our experiment.

This research clearly demonstrates that wild bees can benefit when they consume the secondary metabolites naturally present in floral nectar. And bees’ lifetime exposure to these compounds is likely even greater, since they also consume them in pollen and as larva.

In other research, we’ve uncovered evidence that some of the compounds with anti-parasite function are sought after by bees when they have parasites, but not when they are healthy. At least in some contexts – including a field experiment with wild bees naturally infected with Crithidia bombi – bumble bees make foraging choices in response to parasite status, similar to other animals that self-medicate.

Rx for struggling bee populations?

So what about practical applications: could this research be leveraged to help declining bee populations? We don’t know yet. However, our findings suggest some interesting questions about landscape management, pollinator habitat gardening and farm practices.

In future work, we plan to investigate whether planting particular plants around apiaries and farms would result in healthier bee populations. Are native plants important sources of medicinal compounds for bees with which they share long evolutionary histories? Can farms that depend on wild bee pollinators for delivery of the ‘ecosystem service’ of pollination be better managed to support bee health?

Delivery of nectar and pollen secondary metabolites to diseased bees is likely not the only tool necessary to promote long-term sustainability of these ecologically and economically important animals. But it appears that this could be at least part of the solution. Agriculture may come full circle, acknowledging that in order to benefit from an ecosystem service delivered by wild animals, we must consider their habitat requirements.

This article was originally published on The Conversation.
Read the original article.

By Tobias Pamminger, University of Sussex

Ants have a reputation of being industrious hard-working animals, sacrificing their own benefit for the good of the colony. They live to serve their queen and take care of all essential tasks including brood care, gathering food and maintaining the nest.

However, not all ant species live up to their reputation. A handful of ant species have figured out a way to outsource all these essential tasks – by exploiting their weaker cousins.

Six-legged slave drivers

These so-called “dulotic” or slave-making ants specialise in robbing brood from other species. This happens during regular raiding events in which slave-making ants attack neighbouring ant nests, slaughter the adults and carry their unborn young home to their nest.

This new generation of ant workers hatches and, having never known their own kin, accept their new masters and carry out their bidding. For instance, they have to care for the brood of the slave-makers – such as feeding and cleaning – because slave-maker worker ants are specialised “raiding machines” and have lost the ability to perform such basic tasks themselves.

The slave-makers become so specialised that they can’t even feed themselves any more and need to be fed by their slaves.

However, not all slaves accept their fate willingly. Some violently tear their masters’ offspring to pieces, depositing the remains outside the nest. This type of “rebellion” is widespread among the ant species Temnothorax longispinosus which are enslaved by the North American slave-making ant Protomognathus americanus. These tiny ants (~2-3mm) inhabit the leaf litter layer of mixed forests on the east coast of the USA and the southern parts of Canada, residing in hollow sticks and acorns.

Unknowing victims

It is tempting to take an anthropocentric perspective on this behaviour and interpret it as the well-deserved revenge of the oppressed servants, getting even with their barbaric masters. However, this interpretation is in all likelihood far from reality. These kidnapped ants do not “know” that they are slaves.

When young ants hatch, they learn the scent of the nest and its inhabitants and accept it as their home. In most cases this system works well, as ants hatch in the nest in which they were reared. However, the majority of ants are able to learn and accept a wide scent spectrum, including the odour of another ant species. This is probably one of the reasons why slavery in ants works – young ants can and will learn the odour of the slave-making nest and accept it as their own.

From an evolutionary perspective, slave rebellion in ants represents an interesting problem, because enslaved ants do not benefit from their behaviour directly. As slave-makers are much bigger and stronger, slaves never attack their suppressors directly, but instead target their masters’ helpless offspring. This guerrilla strategy helps to keep the number of slave-makers small – but will never actually achieve an “overthrow” of the slave-making ants.

Evolutionary puzzle

In order to solve this problem, one has to consider the life history of the enslaved ant species. These ants inhabit a shifting and fragile environment, residing in temporary nest sites – usually acorns – in the forest leaf litter. This environment forces the ants to relocate on a regular basis and sometimes the colony divides if more than one suitable nest site is found. As a consequence, many of these little ant societies inhabit multiple nests in close proximity to each other.

During raids, slave-making ants usually attack only one nest at a time and only carry out a few during any given year. As a consequence, there is a chance that the kin of some enslaved workers will have survived the attack and still live in close proximity to the slave-maker colony that has incarcerated their sisters. By rebelling, slave workers effectively reduce the number of slave-makers in the nest.

As raiding is a labour-intensive business, fewer slave-makers result in fewer raids on surrounding ant nests – which in turns means that their relatives, hiding in an acorn close by, have a better chance to go undetected. So by rebelling, slave workers don’t help themselves but protect their close family.

In a new study, we investigated this hypothesis. We mapped the exact location of hundreds of ant nests, including information on the relatedness of its inhabitants – both to each other and to enslaved ants in the vicinity.

Our results bear this theory out. No one really knows precisely why the slave ants attack their masters’ offspring, but the result of these rebellions – whether it is known to the slaves or not – is to increase the life chances of their relatives in nearby nests.

This article was originally published on The Conversation.
Read the original article.

According to the Research and Innovation Communications team at Ohio State University, a species from this ‘extremophile’ family hasn’t been described for 40 years. They say it only “sort of” looks like a worm and moves like a worm, but it is a previously unidentified microscopic species of mite that was discovered by a graduate student on Ohio State campus.

When the Ohio State’s Acarology Laboratory Affectionately nicknamed the mite the “Buckeye Dragon Mite”, officially named Osperalycus tenerphagus, Latin for “mouth purse” and “tender feeding,” it was a nod to its complex and highly unusual oral structure. This new mite doesn’t exactly resemble a mythological winged dragon, but more the snake-like Chinese dancing dragons that appear in festivities celebrating each new year. What it does not resemble is a typical mite characterized by a large round body and tough external surface. And at 600 microns, or just over half a millimeter, the adult mite cannot be seen by the naked human eye.

“It is incredibly intricate despite being the same size as some single-cell organisms,” said Samuel Bolton, the doctoral student in evolution, ecology and organismal biology at Ohio State who discovered this species. “That’s the fascinating thing about mites and arthropods – mites have taken the same primitive and complex form and structure that they’ve inherited and shrunken everything down. So we’re dealing with complexity at an incredibly small scale.”

Bolton’s description of Osperalycus tenerphagus is published online in the Journal of Natural History. It is the fifth species from this worm-like family, called Nematalycidae, to be described, and only the second from North America.

The Butterflies! exhibit at Drexel University in Philadelphia has given birth to a live Lexias pardalis was a shocking delight when it was spotted. Chris Johnson, a volunteer for the university’s Academy of Natural Sciences, was working on the exhibit when he noticed a brand-new butterfly slowly spreading its wings. Since the wings were so different from each other, it became apparent right away that this was a different kind of butterfly than the rest of the flock. The wings show that this was a hermaphroditic animal known with a condition called bilateral gynandromorphy making it exactly half female and half male.

Discovery News interviewed Entomology Collection Manager and lepidopterist Jason Weintraub, who had this to say:

“Gynandromorphism is most frequently noticed in bird and butterfly species where the two sexes have very different coloration. It can result from non-disjunction of sex chromosomes, an error that sometimes occurs during the division of chromosomes at a very early stage of development.”

Gynandromorphism is difficult to spot in many species whose male colorations are not different than their male counterparts, but because of this distinction in butterflies and many birds, it allows scientists to track just how rare it is.