Last night I presented a webinar on "Wasps: The Astonishing Diversity of a Misunderstood Insect" to the Athol Bird & Nature Club. Here is the embedded recording from Youtube if you would like to view it. I cannot guarantee an indefinite duration for the link. Thank you.
Thursday, January 12, 2023
Wednesday, December 7, 2022
A Potential New Host Record for Calliephialtes grapholithae (Hymenoptera: Ichneumonidae) from a Paper Wasp nest (Hymenoptera: Vespidae: Polistes metricus)
It started out innocently enough. Back in 2021, a Facebook post by Sloan Tomlinson (@thatwaspguy on Twitter) caught my attention. He had reared small parasitoid wasps, Elasmus polistis, from an abandoned paper wasp nest that he had contained. I messaged him to learn more, and then followed his suggestion to try this myself.
We had a nest of the Metric Paper Wasp, Polistes metricus, in a corner of the recessed frame of our back porch doors (French doors) at our home in Leavenworth, Kansas, USA. After the wasps left, I cut down the nest and placed it into a plastic container. Shortly thereafter, in about mid-November, a large number of small parasitoid wasps emerged that were not the same as those that Sloan Tomlinson had reared out. That is a separate mystery from the one I am documenting today.
This year, 2022, we had two Polistes metricus nests, one in each corner of the door frame. One succeeded better than the other by a substantial margin, and I repeated the exercise of cutting down the larger nest and containing it in late autumn. Besides the large number of tiny, metallic parasitoid wasps, I got a shocking surprise.
My partner, Heidi, and I went on a vacation in late October. When we returned, I was amazed to find a live female ichneumon wasp, one nearly deceased male, and one deceased male, inside the container with the Polistes nest. The insect was not one of the species that is a known parasitoid of paper wasps. I was able to identify it as Calliephialtes grapholithae, but that made no contextual sense. All of the known hosts for that species are caterpillars of moths.
Previously recorded hosts for C. grapholithae include larvae of the following Lepidoptera: Acrobasis betulella, (formerly A. hebescella), A. juglandis, A. rubrifasciella (recorded as A. nibrifasciella (Pyralidae: Phycitinae); Carmenta texana (Sesiidae: Sesiinae); Cydia caryana (recorded as Laspeyresia caryana, the Hickory Shuckworm, Tortricidae: Olethreutinae); Meskea dyspteraria (Thyrididae: Siculodinae); Periploca ceanothiella (recorded as Stagmatophora ceanothiella, Cosmopterigidae: Chrysopeleiinae); Thyridopteryx ephemeraeformis (Psychidae: Oiketicinae); Megalopyge opercularis, the Evergreen Bagworm (Megalopygidae). Most of these taxa represent a “concealed host,” such as the Evergreen Bagworm and Hickory Shuckworm.
The only way the association of C. grapholithae with paper wasps can be made is if there is a moth larva involved in some fashion. It so happens that there is. The Sooty-winged Chalcoela, Chalcoela iphitalis, is such a moth (Crambidae: Glaphyriinae). The caterpillar stage is predatory on the larvae of Polistes wasps, inside their nests. Webbing spun by the caterpillars is a clue to their presence. Apparently, the adult female moth approaches the nest at night, when the adult wasps are less alert. Still, she may lay her eggs on the back of the nest, and let her tiny larval offspring find their way into a cell.
Sure enough, I happened to notice one of these moth caterpillars, strikingly similar to a paper wasp larva, in the bottom of the container with the nest and its other associates. There is little doubt in my mind that C. iphitalis is a host for the ichneumon wasp Calliephialtes grapholithae. The pattern of this wasp seeking concealed hosts fits, though how the wasp navigates a well-defended nest of paper wasps is beyond my imagination. I am hoping that such an infiltration can be documented, or that someone else will independently rear the ichneumon from a paper wasp nest. Until that time, I cannot assert, unequivocally, the host relationship.
I also wonder if the sever drought experienced by eastern Kansas this past summer had anything to do with the proliferation of the moths that plague the paper wasps. I noticed more than usual. One of the two nests almost failed completely, though one of the foundress wasps may have died prematurely, slowing the nest’s rate of growth, eventually halting it.
Much remains to be discovered about even the most common of insects, especially when it comes to ecological relationships to other species. I urge my readers to undertake what observations and experiments they can to further enlighten our understanding of the natural world.
Sources: Carlson, Robert W. “Database of Hymenoptera in America north of Mexico,” Discover Life
Hoskins, Jonathan. 2021. “Species Calliephialtes grapholithae,” Bugguide.net
McCormac, Jim. 2017. “Wasp-eating moth fills rare niche,” Ohio Birds and Biodiversity
”Calliephialtes grapholithae,” iNaturalist.org
Sunday, November 6, 2022
The Changing Conversation Around Invasive Species
Recently, the debate about invasive species has become more polarized than ever, with a degree of defensiveness and anger not seen previously. The reasons for this are many, some difficult to admit to.
I attended a webinar a few weeks ago in which the presenter asserted that “invasive species” is a “militarized term.” My instinctive reaction was that this was accusatory, bordering on defamation of science, when there is clear evidence that the introduction of a species to a new ecosystem can have devastating consequences.
Pondering his comment further, it occurred to me that most of the animals, and plants, we label as invasive have some sort of obvious and negative economic impact. We have, as a consumer culture, become conditioned to frame everything in terms of business and monetary interests rather than ecological concerns. This has become more complicated by angst over climate change, and the resulting vulnerability of humanity to emerging threats, be they viruses or “murder hornets.”
The sudden, and/or overwhelming appearance of a novel organism is going to cause alarm, and the public seldom has comprehensive, appropriate knowledge for interpretation of potential impacts. We are at the mercy of what news outlets tell us. Because traditional print, radio, and television media now compete with social media, sensationalism is the order of the day. “Click bait” banners prevail over more accurate but less provocative headlines.
Initial forecasts can also be premature. The jury is still out on whether some recently-introduced species will become problematic. They may not. The Joro Spider is a case in point. It is locally abundant in some parts of the southeast U.S., but whether this translates to a displacement of native spiders remains an unanswered question.
We collectively have a fascination with heroes and villains, too, and there are no more menacing villains than alien-looking insects, spiders, and other arthropods. Fantasy melds with reality and it becomes difficult to separate the two if you are not scientifically literate, or have a business model that demands public hatred of a particular creature.
In opposition to nativism is the idea that there is no such thing as invasive species. After all, man is part of nature, and therefore our actions are natural processes. The outcomes of those activities are circumstances to which we, and other species, will adapt.
It may be no coincidence that a backlash against the idea of invasive species is more evident now that we are recognizing, and attempting to mitigate, a history of colonialism. A convincing argument could be made that White settlers are the original invasive species. Here, in North America, we annihilated and displaced Indigenous members of our own species. We enslaved others. To this day we continue missionary work and other forms of colonialism. Therefore, the idea of invasive species becomes one of self-loathing, certainly an eventual threat to White supremacy and privilege. White people do not want to see themselves as villains.
Meanwhile, we demonize human immigrants and refugees as criminals and threats to domestic labor pools. We clamor for the closure of borders to our fellow humans, but allow our boundaries to be permeated by everything else. Not that human-imposed boundaries reflect natural ones.
Scientists have an uphill battle in resolving these opposing perspectives and initiating constructive dialogue. Looking to the past we see how some species from foreign lands have become “naturalized” over time, becoming innocuous additions to our flora and fauna. The average citizen may be shocked to learn that dandelions are not native to the U.S. They have become a fixture in our lawnscapes, even if we are instructed to use weed-killers against them.
What is lost in all of this is attribution of the modern problem of invasive species to global consumer culture. Historically, human colonists brought other species with them as a guarantee of food and other necessary resources when venturing into unknown territory. Soon after, those species and their products became valuable in trade, a way to establish meaningful and positive relationships with Indigenous peoples, or other settlers. The pace of travel was slow, and the scale of enterprise miniscule compared to twenty-first century business.
Today, we mostly covet plants and animals of far-off lands. Plants, especially, can harbor potential insect pests. Thecontainers used to transport international commerce are frequently occupied by insects, rodents, and other organisms. We seldom make that connection between our consumer habits and the state of ecosystems around the world.
We cannot turn the clock back, but we should make more informed and conscientious individual choices in the marketplace. We should promote the welfare of Indigenous peoples, and actively seek their counsel and leadership in crafting a world better able to withstand climate change. A permanent end to colonialism would not be a bad thing, either.
Monday, October 24, 2022
Fall (Bug) Colors
October is the heart of autumn in many parts of North Amreica, with intensifying colors of fall foliage. Insects reflect the changing hues of plants, the better to camouflage themselves. As chlorophyll recedes, xanthophyll (yellow) and other carotenoids (orange), begin to manifest. Anthocyanins (reds to purples) become prominent, too. Could it be that insects feeding on those leaves take on the same colors? Perhaps the insects are merely responding the shrinking period of daylight as the leaves are doing.
This year, here in northeastern Kansas anyway, an exceptionally dry summer has resulted in subdued fall colors. Green leaves persist, even if they are withered from a record-breaking hard freeze last week. Some insects insist on being wholly green, or at least partly so.
Beige is an overwhelmingly common color of fall in pastures and fields, and even lawns thanks to our current drought. Insects of the same color merge seamlessly with grasses and weeds, becoming nearly impossible to detect unless they move. On windy days it is even more of a challenge. Thankfully, for entomologists and bugwatchers, insects frequently alight on, or are blown onto, sidewalks, the sides of buildings, and other surfaces where they stand out.
Many insects with warning colors are bright yellow, and black, regardless of the seasons, but in autumn they complement the colors of plants.
Orange and red are less common colors in insects, and often part of the loud wardrobe of aposematism (warning colors), or mimicry of other insects that are well-defended by venom or toxins. Lady beetles defend themselves by autohaemorrhaging, or “reflex bleeding,” from leg and body joints. An alkaloid toxin in the haemolymph is aromatic and sticky, quite repulsive to would-be predators.
Many insects are iridescent, often vividly so. Whereas the preceding colors are expressed by pigments that absorb all wavelengths of light except the one we interpret as brown, beige, green, yellow, orange, or red, or black, iridescent colors are produced by a different mechanism. These structural colors are rendered by micro-sculpturing, and/or layering, of the cuticle of the animal’s exoskeleton. Light bounces and reflects, and the color we see varies depending on the angle of the light hitting the organism.
A few insects are white, or appear so at least. This is especially the case for true bugs that exude waxy secretions to protect themselves from desiccation and make themselves distasteful to predators. Leafhoppers display almost every color combination imaginable in patterns of spots, blotches, stripes, bands, and speckles.
Keep looking for colorful “bugs,” deep into fall. Some will enjoy your rotting Jack-O’-Lantern. Others will find their way indoors, preferring the same comfortable climate you yourself enjoy. Meanwhile, I will do my best to keep cranking out blog posts to help you identify them. Stay warm and dry, friends.
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