insects

A Weakness for Weevils

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I was excited to find a new weevil on our property the other day. At least until I identified it.

Meet Otiorhynchus sulcatus—the black vine beetle—pest on a wide range of garden plants, including grapes, black currants and strawberries (all common in my garden).

I admit, I have a weakness for weevils—no matter how much of a pest they are, I think they’re cute. And this one is no exception. She’s lovely, in spite of her diet. And I’m certain she’s a ‘she’, because no males of this species have ever been found. The black vine beetle reproduces parthenogenetically, producing viable eggs without the need for fertilisation by males. 

This ability is the result of a bacterial symbiont in the genus Wolbachia. When researchers in California eliminated Wolbachia in black vine beetles (by giving the beetles antibiotics), the beetles’ unfertilised eggs were no longer viable. It’s a clever little ploy by the bacterium to ensure its own reproduction—only infected insects can reproduce, and they can do so without the trouble of finding a mate (I wrote more about this fascinating relationship in Putting the Science in Fiction and on Dan Koboldt’s Science in Fiction blog).

Another cool feature of the black vine beetle is that it is flightless. It’s not uncommon to find flightless insects and birds here in New Zealand, but it’s a little unusual to see it in invasive pests like the black vine beetle. Native to Europe, the black vine beetle is now distributed all around the world. Pretty impressive travelling for a 6 mm-long flightless insect.

Apparently black vine beetles can cause significant damage to plants. The larvae eat roots in the soil and do the most damage, particularly in potted plants, where root growth is limited. I’ve decided not to worry about them at the moment. I’ve got more damaging pests to worry about, and to be honest, I wouldn’t mind seeing them again. They are awfully cute.

Putting the Science in Arthropod Borne Disease

/ Robinne Weiss / 1 Comment

Aedes aegypti (US Department of Health and Human Services)

The slam of a screen door—a quintessential part of summertime in the United States.

But not here in New Zealand. Most houses have no screens in windows or doors.

Why? Because we don’t have arthropod-borne diseases (of humans) here.

The ubiquitous window screens and screen doors in the US are a direct result of the efforts to eliminate malaria in the early 1900s. In some areas, screens were mandated by local government. They caught on, even in areas where they weren’t required, and remain popular today, in spite of the fact malaria is no longer endemic to the United States.

Lone Star Tick–transmits ehrlichiosis and a carbohydrate that can trigger meat allergies. (Centers for Disease Control and Prevention, Dr. Amanda Loftis,  Dr. William Nicholson, Dr. Will Reeves, Dr. Chris Paddock)

Arthropod-borne diseases have shaped human cultures, changed the course of wars, and stymied economic development throughout the world for millennia. Malaria alone kills 400,000 people annually, and hundreds of millions of people worldwide suffer from other arthropod-borne diseases like Chagas disease, yellow fever, dengue and leshmaniasis.

Arthropod-borne diseases are transmitted from one person to another by, you guessed it, an arthropod—often a mosquito, fly, or tick. These arthropods (just the females, in the case of mosquitoes) feed on human blood. They draw up the disease from a sick person with one meal, and transmit it to another person with the next. The disease—a virus, protozoan, plasmodium, flatworm, or other organism—often has a complex life cycle, requiring specific hosts and specific vectors in order to complete each stage of its life. Combating these diseases requires an understanding of every part of the life cycle of both the disease and the vector.

Though humans have been battling malaria for the entirety of recorded history, new arthropod-borne diseases emerge regularly, challenging public-health systems worldwide. With increased air travel, infected people and vectors can quickly spread diseases to new places. And diseases don’t necessarily act the same when transplanted into a different population.

Zika is a great example of the complex interactions between host, vector and disease that make arthropod-borne diseases so scary and difficult to combat. Zika was first identified in humans in 1952, after first being found in monkeys. It was confined to Africa and Asia until 2007. Only 14 cases were documented, though testing indicated people had wide exposure to the virus. Symptoms were usually mild, and it wasn’t considered a major problem.

The first large Zika outbreak occurred on the island of Yap in Micronesia in 2007. Further outbreaks in the Pacific Islands in 2013 and 2014 brought the first information connecting Zika with congenital malformations like microcephaly and severe neurological complications.

Then, in March 2015, Zika appeared in Brazil. Because Zika was unknown in Brazil, the outbreak wasn’t identified as Zika until May. In October, Brazilian health officials reported a dramatic increase in microcephaly, which was linked to the Zika outbreak.

By the end of 2015, Zika outbreaks had been reported all over Central and South America.

In February 2016, the World Health Organization declared Zika a Public Health Emergency of International Concern. Emergency plans were enacted to control the spread of the virus by eliminating the suspected vector mosquitoes, Aedes aegypti, and to study how to manage the complications of the disease.

The disease and our understanding of it moved rapidly throughout 2016. The virus was found in another species of mosquito. It was proven to also be transmitted through sex and through blood transfusions. It was discovered to cause a much wider range of neurological problems than first thought. Vaccine development began. Travel advisories were put in place. Innovative new mosquito control strategies were launched.

Still, Zika spread and infected over 180,000 people. By November 2016, it was clear Zika was here to stay, and needed to be managed on an ongoing basis, not as an emergency. In the space of 18 months, Zika had invaded the world.

The full timeline of Zika can be found on the WHO’s website: http://www.who.int/emergencies/zika-virus/history/en/

The WHO also has great information about other arthropod-borne diseases: http://www.who.int/campaigns/world-health-day/2014/vector-borne-diseases/en/

All the real-life science of arthropod-borne disease can make for exciting fiction. Fancy writing a story? Here are a couple of ideas to get you going:

1. A cluster of people in a small town in Iowa fall ill with an unusual rash that progresses to a deadly autoimmune disease. Doctors are stymied until one of the women mentions she’s just returned from a trip to Africa. Blood tests confirm she is carrying antibodies to a rare arthropod-borne disease not seen outside of Sub-Saharan Africa before.

  • How do researchers try to contain the disease? The first step is usually to quarantine sick people and those who have come into contact with them, but if this fails, control has to turn to other ways of breaking the disease cycle. Strategies may include vaccines, preventive medicine, killing the disease vectors, eliminating the vectors’ habitat, and separating people from the vector (with screens, curfews, etc).
  • Is there a competent vector for the disease in Iowa? In its native range, the disease may be vectored by an arthropod not found in North America, but some widespread arthropods are capable of vectoring many diseases. Arthropods within the same genus of the original vector are most likely to be able to transmit the new virus.
  • How does the progression of the disease in Iowa differ from in Africa, where people have been exposed to the disease for longer, and have developed a measure of immunity. Mild diseases can become deadly in populations never exposed to them before.
  • How does society as a whole react to disease survivors? The social impact of emerging diseases can be as devastating as the disease itself—survivors may still be sources of infection, and some arthropod-borne diseases can also be spread through other means (sexually, in feces or saliva, etc). How does this affect those who survive?

2. A government wants to unleash a new arthropod-borne virus to wipe out a rival nation (Don’t laugh, Japan tried to do this during WWII, breeding up disease in prisoners of war and releasing cholera-infected flies and plague-infested fleas in China, killing more people than the atomic bombs on Hiroshima and Nagasaki).

  • How will they choose a vector and disease to minimise the danger to their own people? Will they vaccinate their own people first? Or chose a disease already present in their country, but not in the target country?
  • How will they deliver live, infected vectors to the intended target?
  • How will they produce enough of the disease organism to infect the vectors?

And don’t forget to get yourself a copy of Putting the Science in Fiction, to be released on October 16! This is a great resource you don’t want to miss!

Science and technology have starring roles in a wide range of genres–science fiction, fantasy, thriller, mystery, and more. Unfortunately, many depictions of technical subjects in literature, film, and television are pure fiction. A basic understanding of biology, physics, engineering, and medicine will help you create more realistic stories that satisfy discerning readers.

This book brings together scientists, physicians, engineers, and other experts to help you:

  • Understand the basic principles of science, technology, and medicine that are frequently featured in fiction.
  • Avoid common pitfalls and misconceptions to ensure technical accuracy.
  • Write realistic and compelling scientific elements that will captivate readers.
  • Brainstorm and develop new science- and technology-based story ideas.
  • Whether writing about mutant monsters, rogue viruses, giant spaceships, or even murders and espionage, Putting the Science in Fiction will have something to help every writer craft better fiction.

Putting the Science in Fiction collects articles from “Science in Sci-fi, Fact in Fantasy,” Dan Koboldt’s popular blog series for authors and fans of speculative fiction (dankoboldt.com/science-in-scifi). Each article discusses an element of sci-fi or fantasy with an expert in that field. Scientists, engineers, medical professionals, and others share their insights in order to debunk the myths, correct the misconceptions, and offer advice on getting the details right.

Go in the draw to win a FREE copy of Putting the Science in Fiction

Kaitorete Spit: An Overlooked Gem

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Earlier this week, my daughter and I hiked onto the Banks Peninsula from Birdlings Flat. The walk afforded us gorgeous views of Kaitorete Spit.

Kaitorete Spit is only about 6000 years old, but is an important natural and cultural resource. Te Waihora / Lake Ellesmere, formed by the spit, is home to or visited by 166 species of birds and 43 species of fish which support commercial fisheries, recreational fishing and hunting, and traditional food gathering. In spite of its harsh, exposed environment, Kaitorete Spit is home to a remarkable number of threatened plants and animals, including pīngao (a native sand sedge prized for weaving), a flightless moth, and the katipo spider. A variety of lizards also flourish on the spit. The lake and spit have been important sources of food and fibre for Māori since they arrived in the area. Fragments of the oldest known Māori cloak were uncovered on the spit, dating to around 1500 AD, and many other signs of early Maori use of the spit have also been found there.

In pre-European times, Māori used the spit as a convenient highway as they travelled up and down the island. Unfortunately, the shifting gravel of the spit and the regular opening of the lake to the sea mean the spit isn’t passable in anything but the most capable of four-wheel drive vehicles. Today, travellers make the long trek all around the lake, so our home near the pointy end of the spit is a 40-minute drive from Birdlings Flat, just 25 km away on the fat end of the spit. But I’m happy to leave the spit to foot traffic—it helps protect the unique plants and animals that live there.

On a windy, wet day, Kaitorete Spit is a miserable, exposed place to be, but visit it on a warm sunny day, and you’ll see why it is an overlooked gem.

Spring Babies

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It’s that time of year again! The preying mantis egg case I collected in the autumn is hatching.

Because these mantids were in the warm office for half the winter, they’re early. Mantids in the egg cases outdoors haven’t yet emerged. So they need a little extra care. As the babies emerge, I transfer them to a large tank where they’ll be warm and well-fed for a few weeks while the weather improves. Eventually, I will release most, keeping only a few for use in educational programmes.

I never tire of this annual event. I love watching the newborn mantids stretch their legs and catch their first meal. And I’m always amazed that so many insects can emerge from such a small egg case. The current one, just 15 mm long, has disgorged 35 mantids so far, and only half the case has hatched. The mantids don’t all hatch at once—hatching seems to progress from one end of the egg case to the other over the course of a few days. In the wild, I suspect most of the later hatchlings are eaten by the early ones—it’s a mantid-eat-mantid world out there. It happens in my tanks, too, though I try to minimise cannibalism by spreading them out as much as possible and giving them plenty of hiding spots. I used to raise each individual in its own peanut butter jar, but that gets to be pretty time and space-consuming when there can be 70 mantids in each egg case.

Everyone’s heard the sensational ‘fact’ that female preying mantids eat the males after mating. It does happen, sometimes, in some species, but not as often as you might think. Mantids are creatures of instinct, and one of their most powerful instincts is to capture prey. In fact, this urge is so strong that, even when their digestive system is completely full, and they can’t actually eat anything else, they will continue to capture prey.

So it’s no surprise that a female mantid might snack on her mate, especially since she’s bigger than he is. In species where the females are significantly larger than the males, there’s a higher incidence of cannibalism after mating. Among New Zealand mantids, cannibalism at mating is rare—females are only slightly larger than males, and so the males have a good chance of fighting off the females. I’ve seen this in action in captivity—one of my females had a go at her mate, but he was every bit as feisty as she, and their tussle ended with both alive and unharmed.

My little babies won’t have to worry about mating cannibalism for a while yet, but there are plenty of other dangers out there—other predators, parasites, pathogenic fungi, freezing weather, and careless gardeners all take their toll. Of the maybe 70 mantids that will hatch from my egg case, only one or two are likely to survive to adulthood.

I’ll give my babies the best start I can, and then they’ll be on their own. Watching them now, catching gnats like pros, I think they’re well-equipped.

5 Simple Things You Can Do to Help Conserve Species

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It’s Conservation Week here in New Zealand. Fittingly, one of the kōwhai trees we planted years ago has chosen this week to flower for the first time.

Conservation week is a good time to talk about backyard biodiversity. I’ve blogged more than once about biodiversity issues. It’s a topic near to my family’s heart, and something we strive to improve all the time.

Our yard is, unfortunately, home to a wide variety of non-native weeds, but it also sports native plantings (and even a fair number of native ‘weeds’). Here are just a few of the simple things we’ve done to improve the habitat value of our back yard for native organisms. You could do these, too.

  1. Plant natives instead of non-natives. Here in New Zealand this is especially important, but it’s a good rule of thumb wherever you live. Native vegetation will best support native wildlife, because they evolved together. Choose plants that provide food and shelter for local wildlife—shrubs with berries for birds and lizards to eat, dense grasses that provide hiding spots for invertebrates, and flowers that provide food for insects.
  2. Create lizard refuges. A pile of rocks or a stack of broken terracotta pot shards makes a nice refuge for lizards—the rocks and terracotta warm up in the sun, making a convenient basking spot for the lizards, and the little cracks between ensure a quick, safe get-away when predators appear.
  3. Just add water. Birds, insects, and other animals all need water to survive. Provide a bird bath, a small pond, or an attractive water feature, and you’ll find many more animals drawn to your yard.
  4. Kill non-native predators. Less important in some places, but here in New Zealand, protecting native birds and lizards requires controlling invasive predators. Trap out possums, stoats, and rats to give native birds a chance to nest successfully. Put a bell on your cat and keep it indoors around dusk and dawn when the birds are most vulnerable.
  5. Learn what you’ve got. No matter how small, your yard teems with species. Look closely, and you may be surprised at the diversity. Though our yard tends to be quite dry, we’ve discovered half a dozen species of moisture-loving slime moulds on the property. Once you know you an organism is present, you can tweak your planting and maintenance to protect and encourage it.

And that brings me back to the kōwhai tree, finally blooming. It’s not enough, yet, to attract bellbirds or tūī, across the vast stretches of agricultural land between us and the nearest populations, but someday, our kōwhai and flaxes, along with the neighbours’, may very well support a healthy population of native birds. All it takes is for each of us to care for our own backyards, and collectively we can improve the habitat for all our native species.

Sticky Feet! The Eucalyptus Tortoise Beetle

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Hanging up the laundry this morning, I found this lovely beetle making its way along the washing line. It’s a eucalyptus tortoise beetle (Paropsis charybdis). I see them occasionally, but with only one eucalyptus tree in the yard, they’re not common.

I’m quite fond of tortoise beetles. This one isn’t much to look at, but many species are sparkling gold, and my first glimpse of them, as a kid, was a truly magical experience that I’ve never forgotten. What tortoise beetles have in common is their domed tortoise-like shape.

Their shape, combined with some pretty awesome feet is what keeps them safe.

Tortoise beetles have wide pads on their feet (this one obligingly sat on a clear surface and showed its feet under the microscope). The pads are covered densely in short hairs, like the bristles of a toothbrush. Each hair is moistened by oil, which helps it stick to the waxy surfaces of leaves in the same way two wet drinking glasses stick together if they’re nested. The oil bonds to both surfaces and acts as glue. When disturbed, the tortoise beetle presses its feet against the surface, employing as many as 60,000 sticky bristles (about 10 times more than other beetles have) to keep it attached. These sticky feet, combined with the dome-like shape make it difficult for predators to dislodge the beetle.

Entomologist Tom Eisner performed a series of elegant experiments with the palmetto tortoise beetle, attaching weights to the beetles to see how much force they could withstand before being pulled off a leaf. He found they could hold up to 240 times their body mass. Those are some seriously sticky feet!

So if their feet are so sticky, how do they walk? Eisner showed, by looking at palmetto beetle footprints on glass, that when they walk, they don’t let all the bristles on their feet touch the surface. Their full adhesive power is only deployed for defence.

I don’t think anyone has tested eucalyptus tortoise beetle grip strength, but it’s definitely impressive. I popped this one into a narrow jar, and it never hit the bottom—it reached out with one leg, like some movie superhero, and grabbed the smooth wall of the jar, arresting its fall. Then, when I tried to get it out of the jar, it stuck like glue to the side. I had to slide a stiff piece of paper under its feet, prying them up one by one. It was obliging for the photo shoot, but when I tried to let it go, it stuck itself to the paper. It took a few determined nudges, but eventually I got it to the edge of the paper and it dropped off.

The eucalyptus tortoise beetle is not native to New Zealand, and is considered a pest in the forest industry here. Still, I have to admire the beetles’ sheer tenacity, and am willing to share my eucalyptus tree with them for the opportunity to see those sticky feet in action.

Nifty Nematodes

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Nematodes under the microscope. Image: CSIRO

A week or so ago, during a writing break, I spent some time peering through the microscope in my ongoing quest to find tardigrades in our yard. I had no luck on the tardigrades, but as usual I came across lots of fabulous little invertebrates.

Perhaps the most common creatures under the microscope were nematodes. No surprise, really. Nematodes are the most common multicellular organisms on earth; there are several million in every square metre of soil here in New Zealand. Most are tiny (less than 3 mm). But not all are so minuscule; the largest, a parasite of sperm whales, can grow to 8 to 9 metres in length.

Nematodes can be free-living or parasitic on animals and plants. In fact, most animals (vertebrate and invertebrate) and plants are host to at least one specialist nematode parasite. Free-living nematodes eat bacteria, fungi, or small invertebrates (including other nematodes).

As you can imagine, nematodes are of huge importance ecologically, economically, and from a human health perspective.

Humans are host to about 60 species of nematode. Diseases caused by nematode parasites in humans include: ascariasis (an intestinal infection that can cause growth retardation and a variety of intestinal and other problems), hookworm (causing anaemia and developmental problems),filariasis (a lymph infection, causing swelling in many body parts, including elephantiasis of the legs), trichinosis (an intestinal infection causing diarrhoea, fever, and other symptoms). Many nematode infections are asymptomatic, and it’s likely most of us play host to nematodes for most of our lives.

The control of nematodes is important in agricultural systems. Worldwide crop loss to nematodes is estimated to be 12.3 percent of production (US$157 billion). Livestock and domestic pets are also susceptible to nematode infection, and millions of dollars annually are spent to control nematode infections including lungworm, hookworm, trichinella, heartworm, and many others.

But nematodes aren’t just doom and gloom. They’re integral parts of natural ecosystems, and critical components in nutrient cycling (especially nitrogen) and food webs. They regulate the bacterial population in the soil, and provide food for many organisms (including some fungi, which catch nematodes with lassos, like tiny cowhands). They can be useful, too. Some insect parasitic species are bred to help control insect pests—a highly species-specific, organic control method.

And like the tardigrade, nematodes are tough. A culture of live nematodes aboard the Space Shuttle Columbia were the only organisms to survive the re-entry breakup of the shuttle, making them the only organism known to survive unprotected atmospheric descent.

Still Life with Insects

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I’ve written and discarded half a dozen blog posts over the past week. Nothing seems to be quite right. Out of ideas, I resorted to the book of 500 writing prompts I created for my daughter. A random stab at the non-fiction section of the book brought me to the question: What objects tell the story of your life?

I tried to encapsulate everything in four objects:

The fiddle: made by a neighbour in Panama, given to me for my birthday by my husband. The fiddle not only tells the story of our years living and working among the incredible, resourceful people of Panama, but also tells the story of my lifelong interest in learning to play the violin…an interest which always ended up being pushed aside for other interests. Because I’m interested in learning so many things, there simply aren’t enough hours in the day.

The beetle puppet represents my insatiable curiosity about arthropods, and how that curiosity has bled into my other interests. Peanut butter jars full of bugs on my dresser when I was a kid led to the entomology degree, which led to teaching about insects at Penn State University, and then starting the Bugmobile. And the puppet is only one of many insect-themed and inspired artistic projects I’ve done over the years, as art and science mingle in my brain.

The gardening gloves speak of my weeding addiction and my love of growing food. The gloves are never more than a month or two old, because I wear through them in that time. I think that says it all about gardening for me.

The rock represents adventure, the natural world, and the wild places I have visited and lived in. Like me, the rock has traveled far and has been changed by the stresses it has experienced along the way.

Backyard Biodiversity

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Craterium minutum

I know it’s been a good weekend when I arrive in my office Monday morning to find my microscope in the middle of the desk, and dirt and bits of plant material strewn about.

It means I’ve been outdoors, seeing cool stuff, identifying plants, insects, or other organisms.

Once you start looking at and identifying what lives around you, the variety is astounding. A glance at the citizen science website iNaturalist shows a pile-up of dozens of observations at our address—and those are only the species we’ve bothered to upload.  I’ve identified 58 species of weeds in the vegetable garden alone. We have half a dozen slime moulds, dozens of fungi and lichens, who knows how many insects and other invertebrates. Then, of course, there are the birds, rats, mice, stoats and other vertebrates. I’ve never bothered to make lists of anything beyond the weeds.

So here in the dark depths of winter, I’ve decided to start a comprehensive list of the biodiversity on our little acre and a half. It will take time. It will require my microscope and many Monday mornings brushing dirt off my desk. But wouldn’t it be cool to know exactly how many other species we share this patch with?

And though many of the species I’ll put on my list are ones I’ve noted many times before, I’m sure some will be new and surprising, like the beautiful slime mould, Craterium minutum my daughter found last week.

Because, the truth is, we needn’t travel far to find natural wonders. We merely need to look closely and have a sense of wonder.

Here Comes the Sun

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After weeks of grey, unending drizzle, we’re finally seeing a bit of sun. Mushrooms abound in the yard, revelling in the dank mist we’ve been swimming through for a fortnight. We are all eagerly awaiting passing of the solstice and the lengthening of the days.

Though it is still pretty dark and drear, and the days will still be short for some time, there are signs of the spring to come.

Lambing has started. This is the time of year when the neighbours grow noisy, with lambs and ewes calling to one another day and night.

The preying mantids are gone, but their egg cases are dotted around the yard, promising a healthy population of my favourite predators come spring.

The daffodils and snowdrops are coming up, and I’ve even seen them blooming in other people’s yards.

And tomorrow is the solstice. Friday, the sun will remain above the horizon fractionally longer than it did the previous day. We’ll be on the upswing.