The luxurious life of arthropods

Not only people strive for wealth and comfort. Biologists note that in urban areas inhabited by wealthy citizens, the variety of plants, birds, bats and lizards is higher than in quarters, where people with less income live (clean income and expenses for education and real estate are taken into account). Researchers called this phenomenon the effect of luxury, “Luxury Effect”. Its nature, in general, is understandable. The socio-economic status of citizens affects the state of the environment: development density, the amount of greens, the presence of water. Educated and wealthy people will not asphalt the yard, they will prefer to plant flowers and trees, may be equipped with a pond. The abundance of plants contributes to the variety of urban animals that find food and shelter next to houses.

But recently, specialists of the California Academy of Sciences, the University of North Carolina and the Museum of Natural Science Denmark established that the effect of luxury is also in the premises: the richer the district, the more arthropods in the houses of its inhabitants.

When a person built the first dwelling, arthropods (Arthropoda) were immediately started in it: insects, crustaceans, spiders and ticks. Millennia have passed since then, and at home, especially urban ones, have changed a lot, but they are inhabited by the same types of arthropods. Some of them have taken root so next to a person that they practically do not meet in nature: there are no more wild populations of a racket-prusak.

Just cockroaches, as well as termites, bedbugs, fleas, a paid moth and other unpleasant harmful creatures come to mind when it comes to home arthropods. They are examined by entomologists studying the ecosystems of the dwelling. Almost nothing is known about harmless arthropods separating the shelter with a person, although there are significantly more of them than pests and parasites.

Actually, the work of American and Danish entomologists began precisely with the study of the biodiversity of the arthropod of the home fauna [1]. They examined (of course, with the consent of the owners or tenants) 50 separate houses located in the city of the roles (North Carolina) and its environs, no further than 50 km from the center. There were 554 rooms in the houses, including halls, bathrooms and attics. Researchers collected arthropods from all visible surfaces, even removed the living and dead insects from the web. They got about 10 thousand samples related to 304 families.

Only in four bathrooms and one bedroom there was not a single arthropod. In one house, representatives of 24-128 families were gathered. They are widespread unevenly. Twelve of the most common families are present at least 80% of houses (researchers presented the results as a percentage, although 1% of 50 houses are half a house). Not a single dwelling is complete without tender spiders (Theridiidae), Kozheedov beetles (Dermestidae), Gallice (Cecidomyiidae) and ants (Formicidae). In 98% of houses, the book lice of Liposcelididae from the Senoedov detachment and 96% were found - Sciridae leaf mosquitoes. Most species belonged to four taxons: flies, spiders, beetles and webding (wasps, bees and ants). The species variety of home arthropods is shown in Fig. 1.

The researchers themselves did not expect such a variety, while they believe that in fact it is even more, since the entomologists have ignored the cabinets and boxes and did not move heavy furniture

Sinanthropic arthropods, usually pests or parasites. They bite the inhabitants of the house, spoil the dwelling, books, clothes and food supplies. Interestingly, the pests met researchers significantly less often than harmless arthropods. Proachan-prusaka was caught only in 6%of houses that devour the wood of termites Rhinotermitidae-in 28%, fleas-in 10%, the researchers did not find the Cimex Lectularius bedbugs at all. At the same time, the most common insects, Gallitsa and book louse in the rooms are practically not known to the general public, despite their ubiquity.

Puffic ticks have been honored with special attention, which cause an allergic reaction in people. There are many of them, they are found in 78% of houses. People who want to get rid of them are recommended to remove carpets - a favorite habitat of dust mites, but the authors of the study note that there were most of the carpets in a dwelling where there were most dusty ticks and the floor is wooden.

The biodiversity of arthropods in city houses turned out to be higher than it was customary to think, but most of the described families did not apply to synanthropic, they are not adapted to life in four walls and ran there from the street. Attracted by light or food, they can exist for some time in a human dwelling, but then they will certainly die if they can’t get out. The house of a person is a trap for them.

But if most of the arthropods come to the house from the lawn outside the door, their diversity should depend on the state of this lawn, including the “luxury effect” for them. To verify this assumption, scientists repeated a study in 50 houses within a radius of 65 km from the role. At the same time, they were interested in the diversity of non -isanthropic arthropods, and not the number of each group, so entomologists no longer collected all the creatures what they saw if they belonged to the same species. In addition to species diversity, researchers took into account the volume, area and age of the house, the degree of landscaping of the territory within a radius of 100 and 500 m and terraces, the number of planted plant species, and the owner’s income.

However, all these factors did not explain the variety of home arthropods. The prosperity of the homeowner does not always correlate with the species variety of plants in the yard and on the terrace. A rich person can limit himself to a simple lawn, and an enthusiastic gardener will break amazing flower beds in a small area. It turned out that the variety of home arthropods of the fauna can be predicted by taking into account another factor - the income of the neighbors (Fig. 2). In houses located in rich areas, the variety of arthropods is greater than in more modest quarters, provided that the vegetation around the house is not particularly diverse. If the kindergarten is good, the wealth of neighbors will not affect the number of families of arthropods found in the house. Researchers suggested that in rich areas the low density of development and the quality of the environment around the house compensate for low plant diversity. Researchers data show that the effect of luxury works not only outside, but also inside. However, the results of the work, of course, were influenced by the fact that it was carried out in separate houses. Squeezed fairly wealthy people with income above 33,500 dollars. Perhaps, with a different property census of participants, as well as in the study of apartments and townhouses, the result will be different, and what exactly, the researchers plan to find out. In their immediate plans - work in Australia, China, Antarctica and Madagascar.

Natalia Reznik

1. Bertone Ma, LEONG M., Bayless KM, Malow T. L F., Dunn Rr, Trautwein MD Arthropods of the Great Indoors: Characterizing Diverside Urban and Suburban Homes // PEERJ (2016) 4: E1582, Doi: 10.7717/Peerj.1582.

2. LENG M., Bertone Ma, Bayless KM, Dunn RR, Trautwein MD Exoskeletons and Economics: Indoor Arthropod Diversity Increases in Affect Neighbourhoods // Biol. (2016) 12: 20160322, Doi: 10.1098/RSBL 2016.0322