Systematics And Taxonomy

to classify insects according to the degree of change that they undergo during develop- 97

ment. Although Swammerdam's concept of development was inaccurate, he distinguished clearly between ametabolous, hemimetabolous, and holometabolous insects. A more elaborate scheme of classification, still based primarily on the degree of metamorphosis but also incorporating such features as number of legs, presence or absence of wings, and habitat, was that of Ray and Willughby (1705).* Ray was the first naturalist to form a concept of a "species," a term that was to take on more significance following the introduction, by Linnaeus, of the binomial system some 30 years later. Between 1735 and 1758, Linnaeus* gradually improved on his system for the classification of insects, based entirely on features of the wings. Linnaeus recognized seven orders of "insects," namely, the Aptera, Neuroptera, Coleoptera, Hemiptera, Lepidoptera, Diptera, and Hymenoptera. Of the seven, the first four orders each contained a heterogeneous group of insects (and other arthropods) that today are separated into many different orders. The Diptera, Lepidoptera, and Hymenoptera have remained, however, more or less as Linnaeus envisaged them more than 200 years ago. Like earlier authors, Linnaeus included in the Aptera (wingless forms) spiders, woodlice, myri-apods, and some non-arthropodan animals. He failed also to distinguishbetween primitively and secondarily wingless insect groups.

Surprisingly, perhaps, up to this time no one had made a serious attempt to classify insects on the basis of their mouthparts. However, the Danish entomologist Fabricius, who was a student of Linnaeus, produced several "cibarian" or "maxillary" systems for classification during the period 1775-1798.* The primary subdivision was into forms with biting mouthparts and forms with sucking mouthparts. Like Linnaeus, however, Fabricius included a variety of non-insectan arthropods in his system and, furthermore, based his systems on a single anatomical feature.

De Geer (1778),* who also studied under Linnaeus, appears to have been one of the earliest systematists to realize the importance of using a combination of features as a basis for classification. Such an approach was used by the French entomologist Latreille, who, during the period 1796-1831,* gradually produced what he considered to be a natural arrangement of the Insecta. In 1810 Latreille separated the Crustacea and Arachnida from the "Insecta," in which he included still the Myriapoda. The latter group was not given class status until 1825. In the final version of his system Latreille distinguished 12 insect orders. The Linnaean order Aptera was split into the orders Thysanura, Parasita (= Anoplura), and Siphonaptera, although Latreille did not appreciate that the first group was primitively wingless, while the other two were secondarily so. The order Coleoptera of Linnaeus was subdivided into Coleoptera (sensu stricto), Dermaptera, and Orthoptera. The Phiphiptera (= Strepsiptera), believed to be related to the Diptera in which order they had been included, were separated as a distinct group by Latreille. The Frenchman was also among the earliest systematists to appreciate the heterogeneity of the Linnaean order Neuroptera, splitting the group into three tribes, the Subulicarnes (= modern Odonata and Ephemeroptera), Planipennes (= modern Plecoptera, Isoptera, Mecoptera, and neuropteroid insects1) and Plicipennes (= modern Trichoptera).

During the first half of the 19th century a large number of systematists produced their version of how insects should be classified. A majority argued, like Latreille, that the wings (presence or absence, number, and nature) were the primary feature on which a classification should be established. Yet others, such as Leach (1815)* and von Siebold

1 Insects that are included in the modern orders Neuroptera, Megaloptera, and Raphidioptera.

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

Get My Free Ebook

Post a comment