Rainy weather is the best time for growing lettuces - under cover. Take a look at Jose’s lettuce experiment. We have found that our ‘sweet’ lettuces (90% water) prefer their roots snug – as in these hydroponic bamboo containers that Jose built. We found it curious that lettuce grows faster, and looks better, in this hydroponic-type set-up than in the compost-rich soil pictured below. The really green vegetables, like spicy lettuces, arugula, spinach and mustards do great in compost-rich soil, but it seems that high-water-content lettuces grow better in bamboo. I was surprised and have had to think about why this is so. That’s what experimenters do when faced with unexpected results. Today is Thursday, October 20, 2011, and for the last ten days we have been in what Costa Ricans call a “temporal”: persistent rains, all day and all night, punctuated by periods of torrential downpours; followed by thick, cloudy mist – which is the time you can dash outside and see about the chores; followed by more rain. We have forgotten what the sun looks (and, more importantly, feels) like…
This morning, I noticed that the Pseudosphinx tetrio caterpillars are back on the Plumeria trees again! Back again so soon? Or perhaps hawk moths metamorphose all the time, rather than just during particular seasons. They were here during the month of July/August and now again in October; let’s see how the Plumeria tolerates leafing out again - and again!I’ve started reading about the Animal Kingdom, particularly those groups representing the climax of a specific evolutionary line (birds, mammals and, of particular interest during this rainy season, insects). And, within the insects, I have become quite fascinated by the Subclass Pterygota, Division II – Endopterygota. They undergo complete metamorphosis and develop wings from inside the body (from imaginal buds) compared to Division I – Exopterygota (eg.Dragonflies), which undergo incomplete metamorphosis and develop wings outside the body.
Even more specifically, I’m looking at the ants, bees and wasps (Hymenoptera). The word Hymenoptera comes from: hymen (membrane) + ptera (wing) = hymenoptera (membranous wings). The Hymenoptera have inhabited the planet for over 200 million years and have the second largest number of species in the Insect Class - over 100,000 species have been described worldwide! There are some 17,000 species in Costa Rica and many live here in the Zona Protectora, El Rodeo. Ants, wasps and bees are my focus but I’m also looking at butterflies and dragonflies.
There are myriad butterflies here in the Zona Protectora of El Rodeo, including Morphos, which are quite common. Students and experts come from all over the world to study butterflies and moths (Lepidoptera) here. In fact, our neighbor, Gabriela, has a butterfly species named after her, which was discovered at her home, Finca Hamadryas. I have always loved butterflies but felt overwhelmed by the idea of studying them.
However, they really are the best way to begin studying the Insect Class, so I finally bought the prohibitively expensive DeVries books. Butterfly life-history is an excellent example of complete metamorphosis.
I am also studying a much smaller insect group at the same time: the utterly beguiling Damselflies and Dragonflies (Odonata) with only around 5,000 species (compared with groups such as wasps, butterflies or beetles, which possess over 100,000 species each). I see Dragonflies daily – glittering wings fluttering deep in the forest. They are so beautiful! Dragonflies are always around water. They spend their larval stage in water, where they are voracious carnivores, consuming huge quantities of, for example, mosquito larvae. Another reason to love to odonates! InBio have published a nice field guide on Dragonflies and Damselflies by Carlos Esquivel.
But I get ahead of myself. Before tackling any species of the Insect Class in the Animal Kingdom, where you can quickly get overwhelmed, the student is wise to go back to the beginning and …read the introduction. This is how you really get to know the author of any book and, in the case of biology, become inspired to go beyond just the syllabus, beyond just the question we have on a certain species. And, when we do, we find that species have more in common than not.
All plants, no matter what the species, use inorganic substances to build themselves (photosynthesis).All aerobic animals use glucose and oxygen in a process that produces carbon dioxide, water and energy, usually in the form of heat. This process can be described in the chemical equation:
C6H12O6 + 6O2 = 6CO2 + 6H2O + Energy. My general focus during this long, rainy season is on aerobic organisms adapted to dry land. They all have in common complicated devices to preserve their internal environment. Animals (Protozoa) and Plants (Protophyta) reproduce and respire and have that extra something that makes them alive and not dead. So far even a 3-year old gets that much.
The Insect Class belongs to the Phylum, Joint-Limbed Animals (Arthropoda). The Spiders, Scorpions, King Crabs and Mites Class (Arachnida) are not insects – they are eight-legged. That’s for another day. The Insect Class alone is a huge area of study – hundreds of thousands species. Once again, it’s important to read the introduction and look at what’s in common. In the Plant Kingdom, I have managed to study plants to the Family level, but not often can I nail the Genus and Species. But that’s the goal.
My neighbor, Paul Gloor, reminded me that I must always remember to document not just the Genus and Species, but also the discoverer and date of discovery. Luckily, the Swedish naturalist, Carolus Linnaeus, did a lot of the work for the rest of us. His work, Systema Naturae, 10th Edition (1758), became the basis of the binominal system of nomenclature employed in the classification of animals and plants. Nowaday, you need to go to research websites like Mobot, InBio or the Plantlist.org to study the latest in nomenclature of plants. And yes, I have been most lax in not including, at the minimum – L. – along with the species. In Costa Rica, plants and animals are getting discovered and identified all the time. Taxonomists might change species around within Families and Genera but the species name and discoverer will always remain the same. You just might have to go find it in a different Family…
Why study animal taxonomy now, after years of focusing on botany, trees and medicinal plants? Well, it started long before that day when I wanted to know the name of the hawkmoth caterpillar crawling on my Plumeria trees. Just by looking, you can see how well-adapted insects are in this forest environment. And with climate change, we shall see ever faster adaptations. I am also increasingly intrigued by the relationships observed between insects and plants. Just observing ants, I understand that they are more ancient, better adapted and will survive the human species. They succeed by their numbers alone and exist in virtually every habitat on this planet. Here in the forest, we might not see a collared anteater every day. But we will see ants, wasps and bees every day, whether we want to or not…The ants are just here now – a few feet away from where I stand inside the house in this forest. If a child drops a few crumbs from his cookie, the ants will soon come and clean them up. If a moth inside the house dies and falls to the ground, the ants will soon come take it away. This is harmonic living in the forest. All we have to do is just let the food chain be. This works just as well in the urban jungle, where the Insect Class has also flourished and adapted. No matter how determined the human species is in attempting to annihilate the insects with toxic, chemical warfare, the resistant insects adapt and just come right back. Like that persistent, impertinent weed that just pops right back no matter how determined the herbicidal warfare employed. The smart humans must learn to try a different approach - just coexisting with like-adapted successful species on this planet. We humans are simply part of the cycle. We study the stages in the life-history of an insect which undergoes metamorphosis, in order to understand – and to sometimes develop strategies.
Pterygota undergoes cycles (metamorphosis) – either complete: egg – larva – pupa/chrysalis – adult, or incomplete, as in Exopterygota: egg – larva (nymph) –adult. Each species has its own set of requirements to morph and to survive in the environment. Understanding these cycles, leads to discovery, understanding, and strategies for coexisting. So, what have I learned so far? Well, I am quite fascinated with ‘ovipositors’ – the egg-laying or stinging structures. All Hymenoptera have an ovipositor, that, in the case of say, worker honey bees (Apis mellifica) has been modified from laying eggs to stinging. The sterile worker bees use this weapon much more freely than the queen, who would be deprived of the normal ovipositor function of egg-laying.
Much has been studied of the highly structured communities of honey bees and also many species of ants. Wasps are different – they are usually solitary and parasitic. The wasps use their ovipositor to modify the substrate on which their egg is deposited, making it more favorable for larval development, by altering the plant tissue or by paralyzing, incapacitating or killing the host or prey. It’s not a pleasant image of Life-History but it is fascinating. I sometimes observe wasps ‘casing’ prey. Among the hymenopterans, we see parasitoids, predators and, also, pollinators and agents of biological control. We have much to learn from these ancient species. They will out-survive Homo sapiens, I have no doubt.
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