Take a look inside the conehead termite colony as a queen begins her reign as one of the longest living insects in the animal kingdom.
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Sunday, April 30, 2023
Thursday, April 27, 2023
Ecology of Lice
The average number of lice per host tends to be higher in large-bodied bird species than in small ones. Lice have an aggregated distribution across bird individuals, i.e. most lice live on a few birds, while most birds are relatively free of lice. This pattern is more pronounced in territorial than in colonial—more social—bird species. Host organisms that dive under water to feed on aquatic prey harbor fewer taxa of lice. Bird taxa that are capable of exerting stronger antiparasitic defense—such as stronger T cell immune response or larger uropygial glands—harbor more taxa of Amblyceran lice than others. Reductions in the size of host populations may cause a long-lasting reduction of louse taxonomic richness, for example, birds introduced into New Zealand host fewer species of lice there than in Europe. Louse sex ratios are more balanced in more social hosts and more female-biased in less social hosts, presumably due to the stronger isolation among louse subpopulations (living on separate birds) in the latter case. The extinction of a species results in the extinction of its host-specific lice. Host-switching is a random event that would seem very rarely likely to be successful, but speciation has occurred over evolutionary time-scales so it must be successfully accomplished sometimes.
Lice may reduce host life expectancy if the infestation is heavy, but most seem to have little effect on their host. The habit of dust bathing in domestic hens is probably an attempt by the birds to rid themselves of lice. Lice may transmit microbial diseases and helminth parasites, but most individuals spend their whole life cycle on a single host and are only able to transfer to a new host opportunistically. Ischnoceran lice may reduce the thermoregulation effect of the plumage; thus heavily infested birds lose more heat than others. Lice infestation is a disadvantage in the context of sexual rivalry.
Read more, here.
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Monday, April 24, 2023
Morphology and Diversity of Lice
Lice are divided into two groups: sucking lice, which obtain their nourishment from feeding on the sebaceous secretions and body fluids of their host; and chewing lice, which are scavengers, feeding on skin, fragments of feathers or hair, and debris found on the host's body. Many lice are specific to a single species of host and have co-evolved with it. In some cases, they live on only a particular part of the body. Some animals are known to host up to fifteen different species, although one to three is typical for mammals, and two to six for birds. Lice generally cannot survive for long if removed from their host. If their host dies, lice can opportunistically use phoresis to hitch a ride on a fly and attempt to find a new host.
Read more, here.
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Friday, April 21, 2023
These animals are also plants … wait, what? - Luka Seamus Wright
Explore the incredible adaptations of Elysia chlorotica, a species of sea slug that can photosynthesize food.
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Tuesday, April 18, 2023
Predators, Parasites, and Pathogens of Crickets
Crickets have many natural enemies and are subject to various pathogens and parasites. They are eaten by large numbers of vertebrate and invertebrate predators and their hard parts are often found during the examination of animal intestines. Mediterranean house geckos (Hemidactylus turcicus) have learned that although a calling decorated cricket (Gryllodes supplicans) may be safely positioned in an out-of-reach burrow, female crickets attracted to the call can be intercepted and eaten.
The entomopathogenic fungus Metarhizium anisopliae attacks and kills crickets and has been used as the basis of control in pest populations. The insects are also affected by the cricket paralysis virus, which has caused high levels of fatalities in cricket-rearing facilities. Other fatal diseases that have been identified in mass-rearing establishments include Rickettsia and three further viruses. The diseases may spread more rapidly if the crickets become cannibalistic and eat the corpses.
Red parasitic mites sometimes attach themselves to the dorsal region of crickets and may greatly affect them. The horsehair worm Paragordius varius is an internal parasite and can control the behaviour of its cricket host and cause it to enter water, where the parasite continues its lifecycle and the cricket likely drowns. The larvae of the sarcophagid fly Sarcophaga kellyi develop inside the body cavity of field crickets. Female parasitic wasps of Rhopalosoma lay their eggs on crickets, and their developing larvae gradually devour their hosts. Other wasps in the family Scelionidae are egg parasitoids, seeking out batches of eggs laid by crickets in plant tissues in which to insert their eggs.
The fly Ormia ochracea has very acute hearing and targets calling male crickets. It locates its prey by ear and then lays its eggs nearby. The developing larvae burrow inside any crickets with which they come in contact and in the course of a week or so, devour what remains of the host before pupating. In Florida, the parasitic flies were only present in the autumn, and at that time of year, the males sang less but for longer periods. A trade-off exists for the male between attracting females and being parasitized.
Read more, here.
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Saturday, April 15, 2023
The Defence of Crickets
Crickets are relatively defenceless, soft-bodied insects. Most species are nocturnal and spend the day hidden in cracks, under bark, inside curling leaves, under stones or fallen logs, in leaf litter, or in the cracks in the ground that develop in dry weather. Some excavate their own shallow holes in rotting wood or underground and fold in their antennae to conceal their presence. Some of these burrows are temporary shelters, used for a single day, but others serve as more permanent residences and places for mating and laying eggs. Crickets burrow by loosening the soil with the mandibles and then carrying it with the limbs, flicking it backwards with the hind legs or pushing it with the head.
Other defensive strategies are the use of camouflage, fleeing, and aggression. Some species have adopted colourings, shapes, and patterns that make it difficult for predators that hunt by sight to detect them. They tend to be dull shades of brown, grey, and green that blend into their background, and desert species tend to be pale. Some species can fly, but the mode of flight tends to be clumsy, so the most usual response to danger is to scuttle away to find a hiding place. While some crickets have a weak bite, a member of the Gryllacrididae or raspy crickets from Australia were found to have the strongest bite of any insect.
Read more, here.
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Wednesday, April 12, 2023
This weird trick will help you summon an army of worms - Kenny Coogan
Discover the tradition of worm grunting, and find out why earthworms come to the surface when they sense vibrations in the earth.
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Sunday, April 9, 2023
Thursday, April 6, 2023
Coloration of Spiders
Only three classes of pigment (ommochromes, bilins and guanine) have been identified in spiders, although other pigments have been detected but not yet characterized. Melanins, carotenoids and pterins, very common in other animals, are apparently absent. In some species, the exocuticle of the legs and prosoma is modified by a tanning process, resulting in a brown coloration. Bilins are found, for example, in Micrommata virescens, resulting in its green color. Guanine is responsible for the white markings of the European garden spider Araneus diadematus. It is in many species accumulated in specialized cells called guanocytes. In genera such as Tetragnatha, Leucauge, Argyrodes or Theridiosoma, guanine creates their silvery appearance. While guanine is originally an end-product of protein metabolism, its excretion can be blocked in spiders, leading to an increase in its storage. Structural colors occur in some species, which are the result of the diffraction, scattering or interference of light, for example by modified setae or scales. The white prosoma of Argiope results from bristles reflecting the light, Lycosa and Josa both have areas of modified cuticle that act as light reflectors. The peacock spiders of Australia (genus Maratus) are notable for their bright structural colours in the males.
While in many spiders color is fixed throughout their lifespan, in some groups, color may be variable in response to environmental and internal conditions. Choice of prey may be able to alter the color of spiders. For example, the abdomen of Theridion grallator will become orange if the spider ingests certain species of Diptera and adult Lepidoptera, but if it consumes Homoptera or larval Lepidoptera, then the abdomen becomes green. Environmentally induced color changes may be morphological (occurring over several days) or physiological (occurring near instantly). Morphological changes require pigment synthesis and degradation. In contrast to this, physiological changes occur by changing the position of pigment-containing cells. An example of morphological color changes is background matching. Misumena vatia for instance can change its body color to match the substrate it lives on which makes it more difficult to be detected by prey. An example of physiological color change is observed in Cyrtophora cicatrosa, which can change its body color from white to brown near instantly.
Read more, here.
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Monday, April 3, 2023
What’s worse than a wasp’s sting? Murder - Miles Zhang
Explore the gruesome evolutionary strategy employed by parasitoid wasps where they feed off other animals to grow their offspring.
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