Dirt Roads – Biodiversity Islets Within an Agricultural Desert on The
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8 On Nature in the Czech Republic Ochrana přírody/The Nature Conservation Journal Ochrana přírody/The Nature Conservation Journal On Nature in the Czech Republic 9 and wasps, like mining bee or mason bee. All Dirt roads – biodiversity islets within an these species take part in the pollination of plants. Some are specialised in particular plant species or genera; others take all that abounds agricultural desert on the example of Pálava in the landscape at a particular moment. In the past, varied and richly flowering field margins -of fered sufficient nectar and pollen and a dirt road Protected Landscape Area provided bare soil to build nests. Changes in the structure of the agricultural land- Pavel Dedek scape have meant a significant deterioration in the conditions for solitary bees and wasps. Easily accessible food as well as suitable plac- The impact of industrialised agriculture on biodiversity and ability of our landscape to retain the little moisture which es for nest building have declined. The remain- landscape ‘condition’ is presently a frequent topic of dis- our nature currently endows us with. This contribution will ing unpaved dirt roads in Pálava, however, still cussion with experts from various scientific fields. The -me however not deal with rapeseed and maize fields, but with host interesting hymenopterous species, al- dia and the public are also very interested in the issue, par- that what separates (or at least should separate) blocks of though there are undoubtedly not so many as ticularly in connection with the drought and generally the intensively farmed fields, i.e. increasingly rare dirt roads. in the past. One of the most remarkable ones is sweat bee Lasioglossum marginatum, which is not large or colourful, but their nests and the high activity around them can hardly be missed. Red poppies, blue cornflowers, pink corncock- Although sweat bees (Halictidae family) are les and white chamomiles are replaced by uni- solitary bees, the developmental cycle of their Lasioglossum marginatum workers. Photo Pavel Dedek form verdure, passing into the equally uniform nests of this species is different from all other yellow of ripening corn or flowering rapeseed. members of the family and approaches that of bees and e.g. paralysed spiders, caterpillars etc. paralyse but not to kill the larva. It lays a single That dense network of dirt roads has disap- true social insects. The development of a nest for wasps), lays one egg in each chamber, se- egg on the paralysed grub, from which a larva peared and also the diversity accompanying it takes a full six years and the number of work- cures the nest against intruders, and dies. hatches that will live from the tissue of the immo- has gone. Despite, or all the more, remaining ers in the nest increases year by year. Drones bilised grub for the whole time until it becomes unpaved dirt roads are important – for the land- and fertile females appear only in the last year. The much larger and colourful Scolia hirta can a pupa. scape itself as well as for species diversity. They then copulate and the fertilised females fly be observed on flowering field eryngo (Eryngi- away to found a new nest. Other solitary bees um campestre). Belonging to the wasps, their Members of the spider-hunting wasp family The migration permeability of our landscape is and wasps have a much simpler development. larvae demand ‘meaty’ food. It searches for (Pompilidae) choose a similar strategy. They like still declining. This is not only due to linear infra- A fertilised female builds a nest (e.g. a long cor- larvae of cockchafers (e.g. scarabs of the ge- visiting the flat inflorescences of plants of the structure like roads and motorways, most often ridor with chambers in the ground), supplies the nus Anisoplia). When it finds a cockchafer grub, carrot family and are not rare along well-pre- mentioned in this context. Dense, dark forests different chambers with food (mainly pollen for it stings just enough much poison into it as to served dirt roads. They build their nests on bare and vast land blocks are much more involved in the loss of connectivity. With the isolation of plant and animal populations inhabiting the last remnants of suitable environment, also the probability of their extinction is growing. Maya the Bee and her relatives Stacks of paper have been written about the im- Dirt road below Svatý kopeček hill at Mikulov. Photo Pavel Dedek portance of bees to humans. A great majority of The dense network of dirt roads, which has in- species, many of which we regard (despite neg- these works, however, concentrate on a single tersected our landscape since ancient times, ative connotations associated with the word species, the honey bee (Apis mellifera), while has not only served man and his needs. It has ‘weed’) as rare and disappearing species of our more than 1,300 species of various solitary bees also been a migration corridor and a perma- flora today. Bouquets of field flowers, overflow- and wasps (included in the group of so-called nent habitat of many animal and plant species. ing with colours and shapes, and evoking in sting hymenoptera) live in our country. It is a rich Particularly insects associated with bare and people feelings of harmony and unity with na- group of various shapes, colours and life strate- sparsely vegetated soil have found here exactly ture, used to be a frequent motif in paintings and gies. A large part of them is bound to bare or just what they need for their development. The mar- are a basic motif in ornaments in South Moravi- sparsely vegetated soil (not poisoned by pesti- gins of dirt roads, with transitions to arable land, an folk art. However, an artist would hardly find cides). Their association with bare substrate is Asproparthenis punctiventris, once a dreaded pest. The weevil Coniocleonus nigrosuturatus reappeared in the Czech Republic after 40 years. have thus provided refuge to all sorts of weed inspiration in the present agricultural landscape. often reflected in the vernacular names of bees Photo Filip Trnka Photo Filip Trnka 10 On Nature in the Czech Republic Ochrana přírody/The Nature Conservation Journal Ochrana přírody/The Nature Conservation Journal On Nature in the Czech Republic 11 reach their destination and the remainder dies (hence also the seemingly unnecessary overproduction of eggs). The luckiest in the solitary bee nest undergo a complete recon- struction of their bodies. After the slender larva eliminates the bee foetus and occupies a honey chamber with accumulated food, it transforms into a barrel-shaped immobile lar- va which further feasts on the food which the bee has collected for its offspring. After it has used up all the honey, the larva transforms into another untypical stage, a pseudopupa, and hibernates this way. In spring, the larva transforms again, from a pseudopupa into a legless larva, which can then turn into a true pupa. This is followed by the last, stormiest stage of development: in the pupa, the lar- Black oil-beetle (Meloe proscarabaeus). Photo Pavel Dedek Triungulins – larvae of violet oil-beetle (Meloe violaceus). Photo Pavel Dedek va body dissolves into a pulpous substance soil and supply the chambers with paralysed Weevils – easy and fast from absolutely essential for this threatened which turns into a mature blister beetle, spiders. dreaded pests to dying species group of beetles. which digs itself out of the underground bee Weevils of the Cleonini tribe are another sig- nest to the surface. And the entire cycle can Solitary hymenopterous species often ‘suffer’ nificant group of inhabitants of dirt roads and Blister beetles then start again. Blister beetles thus need from nest parasites. Nearly every thrifty bee or other disturbed habitats with sufficient bare These beetles are a group which has been solitary bees. And the bees in their turn need wasp species has some thief wanting to obtain soil. These are rather large and particularly most affected by extinction over the past cen- non-poisoned bare soil and flowering plants. Fatal mistake by triungulins: instead of solitary bees, the larvae ‘board’ a chafer (Tropinota hirta). Photo Pavel Dedek some food without work. They let the honest attractive beetles with an interesting history. tury. Out of the total number of blister beetles No wonder our blister beetles are not doing bee or wasp build a nest, wait until the host spe- A vast majority of species have undergone (24 species) 11 have gone extinct, another six well. Not many remaining landscape structures was realised in the Nymburk region (https:// cies fills it with sufficient food and then, incon- a drastic decline in the last half century and are on the brink of extinction and only three meet the definition of ‘significant landscape www.spucr.cz/aktuality-z-kraju/archiv/stredo- spicuously, just as a cuckoo, puts its own egg some of them have gone extinct. can be regarded to be relatively safe. All the Conclusion element’ and the role of ‘territorial system of cesky/vystavba-kolejovych-polnich-cest-na- into the alien nest. The described thief scenario above-mentioned factors have contributed to Unpaved dirt roads are habitats and migra- ecological stability’ better than exactly un- -nymbursku.html) and shows that the National is just one of numerous possibly strategies. An interesting case is formed by As- this terrible decline: intensification of agricul- tion corridors, the importance of which is still paved dirt roads do. Despite, many dirt roads Land Registry (NLR) can also build such roads. proparthenis punctiventris. This used to be a ture, decline in landscape variety, the use of increasing in the present altered agricultural only exist on paper (but are in fact sown and On its website, the NLR states among others An example of such an unwanted coexistence dreaded pest of rapeseed.