Leaf Beetles, a source of inspiration.
Being invited this year to write the editorial to the Bolleti de la Societat d’Historia Natural de les Balears, I felt a bit embarrassed and flattered.
What really to speak about ? Sociobiology, altruism, biodiversity, environmental ethics, cladistics or molecular biology ? No, I’ll speak about Timarcha, the leaf beetle I studied all my life and the insect which has actually his best worshippers in your beautiful archipelago : the professor E. Petitpierre, C. Juan and J. Gomez-Zurita.
The genus Timarcha was named by Latreille in 1829 after an Athenian tribune. Fairmaire in 1868, Chapuis in 1874, Weise in 1882, de Marseul in 1883 did their best to decipher the difficult taxonomy of the group. After those, Bechyne came (1948), separated the subgenera and described many species. Recently Daccordi named several new species from Italy, Corsica and somewhere else.
Balearic islands, magic lands, what Geisendorf-des Gouttes (1934) named « les Archipels enchanteurs et farouches » always attracted me. When in october 1951, I visited them for the first time, I had only one obsession: to see, to study the beautiful blue Timarcha present in Mallorca and Menorca and unfortunately missing in other islands. Guided by Josep Maria Palau, the poet entomologist, I saw them, abundant everywhere and I reared them in Brussels during several years. Now, I feel nostalgic about the countryside, the olive trees and Eivissa and Cabrera. The last one, a sad souvenir for a defeated Napoleonian army.
Sociobiology. I don’t believe that Timarcha balearica would be a model for E.O. Wilson. However Timarcha adults are certainly attracted to each other in Sicily and Djerba when they spend the cold winter and early spring under the tufts of Thymelaea. That is only a mutual attraction as that of coccinellids in temperate areas or of Steno tarsus rotundus, an Endomychid, under palm trees in Panama. Strange and still undeciphered mutual attraction of adults probably under a pheromone influence. I saw one day millions and millions of small tenebrionids in a forest in Thailand all aggregated against the trunks of few trees. No apparent reason for this gathering since the weather was warm and humid. Some larvae of chrysomelids and of other insects, like Pergids, group them together into a ring. I named that phenomena « cycloalexy », the ring defence behaviour (Jolivet et al., 1991). Timarcha is far for reaching that intellectual level, but its simple adult gathering should be restudied.
Altruism. So far Timarcha has never shown altruism of any kind. They are independent beings, as adults and even larvae. I doubt that we can find any altruistic motivation in their behaviour. However, among cycloalexic leaf beetles and sawflies, there seems to be some kind of division of labour. The larvae around the ring do not mix with the ones inside. They protect the larvae inside and this way they are helping their brothers and sisters. There are also the leaders when the larvae go searching for food and break the rings (Weinstein and Maelzer, 1997)
Timarcha are endangered species and need to be protected everywhere, namely in the Balears. Building in some areas should be strictly regulated. It is up to the authorities to give enough breeding space to this living fossil. Other species of chrysomelids do not seem to be in danger. Either they are equipped for flying or their breeding places are not menaced.
Biodiversity. Timarcha are diverse and not less than 12O species and 3O subspecies have been recorded in the world. When the study will be more precise, many more species remain to be described. Their distribution, relics of a bigger one in the Pleistocene, is around the Mediterranean basin, except in Syria, Lebanon and Egypt, where probably they were eliminated by desertification. They exist also on the Western coast of the USA and the extreme south of Canada just below the last Pliocene glaciations. Their diversity is actually endangered because they are wingless and cannot repopulate fragmented habitats. They are also extremely sensitive to insecticides. Poor Timarcha, they probably originated in the Jurassic and they are victim of urbanisation. Biodiversity of the species, but also diversity of the food habits since Rubiaceae, Plantaginaceae, Dipsacaceae, Scrophulariaceae, Brassicaceae, Asteraceae, Rosaceae, Ericaceae can feed some of them but as subgenera and species they are very specific in their habits.
Cladistics and Molecular biology.
Fortunately our chrysomelidologists from Mallorca have tried a cladistics analysis for the Timarcha species, linking the morphology, the food-habits, the phylogeography, the chromosome numbers and molecular DNA, to obtain a more coherent classification. As wrote one day one British, cladistics has been said as being abtruse and severely technical. It compiles lists of characteristics and search for matches in a rigorous way, then testing matches against chance occurrences. To me molecular biology seems to comfort my ideas about morphological classification. Before Farrell (1998) and Hsiao (1994) have proposed based on DNA an acceptable classification of Chrysomelidae when others based only on morphology reached only an organized chaos, at least for me a taxonomic heresy. I hope Petitpierre and his team will go on this molecular biology analysis and will try to re-enact Farrell adventure on the evolutionary history of the leaf beetles and will make it acceptable to the average naturalist. Farrell omitted many basic elements in his testing. He omitted namely among many others the Timarcha, which combine apomorphic and plesiomorphic characters and are so evidently primitive on certain sides ( nervous system, male genital apparatus, etc ..) that they probably deserve a subfamily status themselves : the Timarchinae. A complete analysis remains a must and the Balearic team is 100% fit for this experience.
Timarcha, with the Jurassic Timarchopsis, seem to be the dinosaur of the leaf beetles and Crowson shared my ideas in the past. Your Timarcha in the Balears show a blue reflection on their dark cover. Others are dark red in Oregon, some are metallic red in European mountains, one is metallic in Eastern Spain. Normally they are black in the North African steppes as well as in colder Europe. They are named in the Balearic Islands: marietas, margolides, monjes, escarabat de St Joan. Kids in Menorca used to say: « Marieta treu sang o si no te matare ». Similar rhymes are pronounced by children in Normandy or elsewhere based on their reflex bleeding. The black insect rejecting his red blood has always hit the imagination. At least it is a efficient protection against lizards and birds.
Vedi Napoli e poi muori ! So spoke the Italians. I would like one day before dying to visit again your beautiful islands, to see again in his environment your beautiful Timarcha, to join again the olive gatherers in Minorca and to see there the bloody nose beetles running over the grass below the trees. I still remember in 1951 my visit of Cabrera with Pere Palau i Ferrer, the botanist, Josep Palau’s father. He published, I remember, a Flora of Cabrera in Catalan and refused then to have it translated in any other language, when I offered him to have it published in English in Brussels. No Timarcha in the small island and few leaf beetles there, but Timarcha balearica is not far away outside in the big islands. Cabrera is so wild and beautiful that I have to see it again at the beginning of the new millennium and to revisit also the rest of the archipelago.
Farrell, B. D. 1998. Inordinate fondness explained: Why are so many beetles.
Science 281 : 555-559.
Geisendorf-des Gouttes. 1934. Les Archipels Enchanteurs et Farouches.
Editions Labor, Genève.1-645.
Gomez-Zurita, J., Juan, C. & Petitpierre, E. 2000. The Evolutionary History of the Genus Timarcha (Col. Chrys.) inferred from Mitochondrial COLL Gene and Partial 16SrDNA Sequences.
Molecular Phylogenetics and Evolution 14 (2) :304-317.
Gomez-Zurita, J., Petitpierre, E. & Juan, C. 2000. Nested cladistic analysis, phylogeography and speciation in the Timarcha goettingensis complex (Col. Chrys.).
Molecular Ecology 9 : 557-570.
Hsiao, T. H. 1994. Molecular phylogeny of chrysomelid beetles inferred from mitochondrial DNA data.
Proc. 3rd. Int. Symp. Chrys. Beijing 1992. Furth, D. G. (ed.) Backhuys publs., Leiden : 9-17.
Jolivet, P. 1953. Les Chrysomeloidea (Col.) des îles Baléares.
Mém. Inst. R. Sc. Nat. Belgique (2°sér.) 50 : 1-88.
Jolivet, P. 1994. Remarks on the biology and biogeography of Timarcha (Col. Chrys.).
Proc. 3rd. Int. Symp. Chrys. Beijing. 1992. Furth, D. G. (ed.). Backhuys publ., Leiden : 85-97.
Jolivet, P. 1999. Timarchophilia or Timarchomania. Reflexions on the genus Timarcha (Col. Chrys.).
Nouv. Rev. Ent. (N.S.) 16 (1) : 11-18.
Jolivet, P., Vasconcellos-Neto, J. and Weinstein, P. 1991. Cycloalexy : a new concept in the larval defence of insects.
Insecta Mundi 4 : 133-142.
Weinstein, P. and Maelzer, D. A. 1997. Leadership behavior in sawfly larvae Perga dorsalis.
Oikos 79 : 450-455.