Wasps, Motherhood and Ultrasound

Female Pimpla wasp locating a moth pupa. © 2014 Beatriz Moisset

A slender wasp lands on a plant stem and starts gently tapping it with the tips of her thread-like long antennae. Tap-tap-tap, she goes up and down the stem. She may abandon her search and repeat the same process on another plant, and another. When she finally finds what she is looking for, the tapping becomes more pronounced and remains concentrated in a single spot. A Pimpla wasp is delicately built, glossy black with bright orange legs. Its body ends in a sword-like projection used for egg laying and called ovipositor. This is how we know she is a female. Her methodical activity is a preparation for motherhood.

At a hospital an expectant mother is having a sonogram of her fetus. The technician gets the equipment ready, applies gel to the mother's belly and runs a wand over it. The image of the baby inside the womb emerges in the monitor. The invisible becomes visible through the magic of ultrasound technology.

Ultrasound of a fetus. By Pacres. Flickr

These two unrelated events have something in common. The expectant wasp mother is also using ultrasound for the benefit of her progeny. The amazing thing is that she and her ancestors have been using this technology for millions of years. Even more amazing is that she carries all the needed equipment in her tiny body. One big difference is that she is not observing her unborn baby but locating the food her baby will need. Other wasps have an easier time. They hunt for caterpillars, which are relatively easy to find because they make noises when munching away. But a pupa remains perfectly still and requires special equipment to be detected.

The ultrasound equipment used to see a fetus inside the mother's womb consists of a machine that produces high-pitch vibrations, beyond human hearing, and a sensor, called a transducer, that collects and interprets the sounds bounced back from the mother's body, her placenta, and the little body curled up inside.

The Pimpla wasp vibrates her body in a special way, producing ultrasound waves which she transmits to the plant surface through her antennae. She absorbs the bounced back ultrasound through her legs where some tiny organs, called subgenual (below the knee) organs , collect information on the shape, size and location of its quarry. An image develops in her minuscule brain, an image similar to the ones we have all seen of unborn babies inside the womb. Now she knows exactly where to lay her egg.

Pimpla wasp, female. © 2014 Beatriz Moisset

She bends her abdomen and points the sharp ovipositor toward the hiding moth pupa. She inserts an egg on it and leaves. Her mission accomplished, she starts looking for other occult cocoons to lay more eggs on them.

We marvel about bats and dolphins using a similar process, echolocation. It is remarkable that a tiny insect can also use a version of this complicated technology.

AGRIS. Vibrational sounding by the pupal parasitoid Pimpla turionellae

REDIA. The Subgenual Organ in Pimpla turionellae

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Beginners Guide to Pollinators and Other Flower Visitors

© Beatriz Moisset. 2014

Don't Kill Your Friends

Larva of Coleomegilla maculata, pink spotted lady beetle © Beatriz Moisset

Please, don't go about killing any bug in sight. Some of the ugly ones are your best friends. Take the little "alligator" shown here. If you look closely you will notice that it is devouring aphids.

Same as above, notice the aphids being eaten © Beatriz Moisset

 
The aphids escape notice at first sight. They are the ones that are sapping the juices from your plants and this little guy is going around vacuuming them as fast as it can.

Adult Coleomegilla maculata on spring beauty © Beatriz Moisset

And here is the kicker, that ugly bug will turn into a ladybug when it is fully grown.And remember that it probably eats more aphids at this stage than when it is fully grown. So, if you think about it, maybe it isn't ugly after all. It is beginning to look rather pretty, don't you think?

Polished lady beetle © Beatriz Moisset

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© Beatriz Moisset. 2012

Wildlife Food and Non-native Plants

Queen Anne's lace and many visitors. What is it replacing?

I worry sometimes when people insist on seeing the merits of some introduced plant and claim that it is good for wildlife. We are all familiar with butterfly bush attracting butterflies and with the berries and rose hips of several alien plants which feed the birds. I have also seen Queen Anne’s lace blossoms covered with flower visitors. Another example is this blog article about English ivy and pollinators: Pollinators aplenty: English Ivy mixed blessings. The author tells us that the English ivy in his property is attracting numerous pollinators at a time when there aren’t any native flowers. He suggests that we “should step back and view non-natives with less disdain until we understand better what roles they now play in their adopted habitats.”

I think that this philosophy shows a lack of understanding of ecosystems and of what is missing in those that have been altered by humans. We tend to think that habitat loss is something far away, clear-cutting in the Amazon, for instance. We seem to forget that the urbanization and suburbanization of the areas where most of us live are representatives of a huge amount of habitat loss.

When pollinators and birds resort to non-native flowers and berries, it is because the habitat has been severely disturbed and the native plants that were supposed to sustain them are lacking. A healthy habitat is an assemblage of co-evolved and synchronized plants and the wildlife that feed on them. The absence of such plants is a very sad indication that the ecosystem has been dramatically disrupted.

Calling non-native plants beneficial to wildlife is ludicrous. They are merely acting as prosthesis. If I had a leg amputated, I too would sing the praises of a high quality prosthesis, no matter how alien to my body it was. But, I would prefer my own, native and co-evolved with my body, original leg.

Butterfly bush provides nectar to butterflies but very little else, unlike many native plants

Let us not be seduced by the fact that some introduced plants are used by wildlife. Normally, the natives do that job a lot better, plus they provide countless other services to the ecosystem. We are barely beginning to understand the very complex interactions between all the members of a living community. It is becoming apparent that most of them are missing when we mix organisms from all sorts of places.

More on the subject: I do not hate invasive species

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In praise of bare spots in the garden

Eastern tailed blue butterfly on clover

Some gardeners consider any exposed earth as a blemish in need of a cure, be it mulching or reseeding the lawn and watering. But in a well balanced ecosystem even bare spots have a place, and a very important one at that.
How so? Because they provide habitat and housing for an array of unappreciated garden helpers. We should know more about them. The list is long, so I will not try to cover them all, just illustrate a few interesting ones.


Butterflies. We all love butterflies and associate them with flowers and nectar drinking, but the fact is that after they fill up their tummies with nectar; they still need other nutrients, salts. One way of getting the needed salts is to take them from moist soil. It is not uncommon to see a group of butterflies, either all of the same species or several species amiable mixed together, basking in the sun while sticking their long tongues on the wet soil to extract some minerals or drink some water. Many gardeners attract butterflies by providing flowers for nectaring and plants for feeding their young. It helps to go a step further and provide them with some much needed bare ground.

Clustering of bee nests next to a parking lot

Bees. Bees are the most important pollinators, not just honey bees but the countless species of solitary bees. Most species of bees don’t make hives like honey bees. Instead they lead solitary lives, each one tending her own brood. Some nest in hollow twigs or similar holes, but the great majority nest in tunnels underground. Sometimes they cluster their nests near each other creating veritable towns; other times they take advantage of any small patch of bare soil and build their nests there. In general they prefer sunny and well drained spots.

Square headed wasp at her nest

Solitary wasps. Just like bees there are numerous species of solitary wasps that nest in the ground. Many wasps visit flowers for nectar and perform some pollination. But, perhaps more importantly, they hunt for insects to feed their young. A healthy population of solitary wasps would cut down the need for pesticides significantly. Solitary wasps, as well as solitary bees, are not likely to sting and even if they do so when molested their sting is very mild.

Tiger beetle stalking its prey

Tiger beetles. Another form of pest control is the very colorful metallic green tiger beetle. Tiger beetles belong to a group called ground beetles for obvious reasons. They spend most of the time on or in the ground. Tiger beetles are ferocious hunters of insects. If you provide them with some bare soil you can count on them for keeping pest populations down.

In summary, bare spots contribute to the balance of the garden ecosystem. They provide food or habitat for a number of garden helpers, namely pollinators and pest controls. When you consider all their benefits you wonder why we are so unwilling to tolerate them. Shouldn’t we look at them as an integral part of the garden? There are some gardeners that intentionally make some sand piles and make sure that no pesticides get to them.

Beginners Guide to Pollinators and Other Flower Visitors


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How much is a bat worth?

Who would think of putting a dollar value on a bat? Well, it turns out that some researchers have done just that. I am not talking about a baseball bat but about that creature of the night so loathed by some. We tend to associate bats with witches and demons rather than with crops.

Is there a reason for putting an economic value on a bat? The answer is: Yes. Bats feed on flying insects at night. Many of those insects are pests that damage our valuable crops. So it turns out that bats are valuable to farmers.

A group of scientists have been trying to estimate the numbers of insects bats eat and the possible impact on agriculture and forestry if bats stopped supplying this pest control. They published their conclusions in the scientific journal, Science. Through a number of complex calculations of pesticide application and crop losses they came up with a range between $3.7 billion and $53 billion a year in the United States alone. It is not possible to be more precise when considering so many variables. Anyway the numbers are impressive.

It is worth mentioning that these maligned creatures have other functions in addition to the pest control discussed in this study. They are pollinators of many night blooming flowers. Cacti, in particular, are dependent on bats for pollination. Many cacti of the West synchronize their blooming time with the migration of some species of bats. Try to imagine what the West would be like without cacti. Another service, especially in the tropics is seed dispersal. Bats eat the fruits of many trees, such as fig trees and pass the seeds far from the mother trees.

Unfortunately, in recent times, bats are encountering serious problems. There is one disease in particular that is decimating the populations of bats in the United States. This fungal disease, called "white nose syndrome", weakens and kills large number of bats, especially during the winter. Not much is known about this illness, nor there is a cure in sight yet. It is for this reason that the researchers decided to investigate how the loss of bats would affect agriculture. Even lacking more accurate numbers the results are alarming; the losses to crops and forestry could be very serious.

The web of life is very intricate and often we don’t know enough about all the threads that make this tapestry. This is another example of a creature whose value we fail to recognize. It took a threat to the welfare of bats, such as the white nose syndrome for the world to stand up and take notice. We are only now beginning to appreciate the value of the free services provided by these creatures: pollination, seed dispersal and pest control. We have to look at bats with renewed respect. Let us develop a kinder attitude towards our friends, the bats.

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