Mystery Maggots

Caterpillar, not maggot–see the six true legs and 10 prolegs?

The weather has been hot here, and all the doors and windows stand open all day. With no window screens, that means an array of bugs (and the occasional bird) pops in and out of the house. It’s not unusual to find flies, butterflies, damselflies, etc. on the windows. 

Still, I did a double-take when I saw maggots on my desk the other day. I knew they hadn’t flown in on their own—they must have been hatched nearby. I checked for unseen dead things on the shelves above, but found nothing. There was another maggot this morning, and I did a second unsuccessful check for the source. Then, while I was away from my desk for fifteen minutes, another appeared.

This time I pulled out the microscope and had a closer look.

It wasn’t a maggot at all. It was a tiny caterpillar.

I could think of no reason for a bunch of caterpillars to be living on my bookshelves and dropping onto my desk.

Then I remembered earlier in the day I’d shooed a wasp out of the office several times.

Bingo!

The wasp was a European tube wasp. These little insects seek out cracks and holes to nest in. They fill their nests with up to 20 caterpillars as food for their larvae and then seal the nest with mud.

That would explain the bits of dried soil that accompanied some of the ‘maggots’.

We’ve seen the same thing with our native potter wasps. Last year I had to put tape over all the screw holes in the underside of the dining table, because potter wasps were stuffing them with paralysed spiders (and the spiders kept falling out all over the floor).

As I write, the wasp has returned. Empty-handed this time, she’s fossicking around for a new place to raise her young. Maybe she’ll find one her caterpillars will stay in this time.

Sub-Alpine Idyll

We recently went on a lovely hike up Peak Hill, overlooking Lake Coleridge. The start of the track crosses paddocks, but once on the reserve land, the vegetation changes to a beautiful sub-alpine spread of daisies, Spaniard, matagouri, and tussocks. The daisies, in particular, were spectacular—so many were in bloom that the whole hillside looked frosted. The Spaniard was blooming, too, spiky flower heads rising above the daisies like something from a Dr. Seuss book. Native bees, mānuka beetles, and syrphid flies were all taking advantage of the abundance of nectar and pollen. The air hummed with insects.

You could be forgiven for thinking it was a beautiful, peaceful place. And it was, for us. But among the insects buzzing around were predators—pompillid wasps hunting for spider prey, robber flies snatching unwary insects out of the air, and birds snapping up bugs to feed to their young.

And then there were the plants themselves. At least one hapless beetle impaled itself on a Spaniard leaf. 

It may be pretty, but it’s a rough world out there when you’re insect-sized.

Alpine Delights

The family spent a delightful hour on the Dobson Nature Walk in Arthur’s Pass National Park on Wednesday. The track is an easy one, and hiking it quickly takes about 20 minutes. But it’s not a walk you want to do quickly, especially in summer. It winds through alpine and sub-alpine vegetation, including some beautiful tarns, and in summer, so many plants are blooming, it’s hard to take five steps without finding another lovely orchid, daisy, or hebe in bloom.

For me, the best part of the walk is the abundance of sundews in the tarns. As an entomologist, I’m naturally drawn to carnivorous plants like sundews. Sundews catch insects on the sticky hairs you can see glistening in this photo. The hairs are sensitive to both touch and taste, and when they sense a struggling insect, they fold inward to further entangle their prey. Enzymes exuded by the hairs then digest the insect, and the leaf takes up the nutrients in order to grow in the nutrient-poor alpine wetlands. 

These sundews were just beginning to flower—many plants had flower buds, but none had yet opened. The flowers sit above the leaves—an important adaptation, since the plant needs to be pollinated by the very insects it eats.

The alpine summer is short, so when these plants are done flowering, the leaves will slowly shrink into a structure called a hibernaculum that sits near the soil surface and protects the plant through the winter.

Catlin’s River Walk—a little bit of magic

My family and I were in the Catlins last week, in the southeast corner of the South Island. It’s a wild and remote area, home to more penguins and fur seals than humans. No urban adventures here—it’s a place for outdoor recreation.

One of the things we did was to hike part of the Catlins River Track (we didn’t have time to do the full track). It was unlike any other place I’ve been in New Zealand.

In fact, it reminded me most of eastern Pennsylvania, in spite of the fact that it shares not a single common species of plant or animal.

The track follows the Catlins River, a beautiful waterway that cuts through layers of limestone in one little cascade after another. Swing bridges cross the river several times, providing great aerial views of the water (and a little excitement for those who don’t like heights). The forest is old-growth beech which provides habitat for myriad native birds, carefully protected by intensive predator control. 

In addition to the beech, we were delighted to see two species of orchid on the forest floor, red-flowered mistletoes in the treetops, several species of slime mould, some lovely mushrooms, and a beautiful native harvestman. The birdlife was noisy and varied, but we weren’t lucky enough to see any endangered mohua. And, amazingly, there wasn’t a single sandfly! 

The whole effect was one of an enchanted forest. We were certainly enchanted.

The track is relatively flat—easy hiking for kids or those who can’t face the usual Kiwi hiking track going straight up a mountain, and because there’s no “goal” to reach, you can simply walk as far as you’d like, and then return. The entire length is 12 km one-way, with a return loop option through forestry land away from the river. 

I highly recommend this track. I’ll certainly be going back when I have enough time to do the whole thing.

A Weakness for Weevils

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

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

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.