Insect Diversity

molecular or combined morphological/molecular analyses have come out strongly in sup- 43

port of a Strepsiptera-Diptera sister-group relationship (see references in Whiting, 1998 and Wheeler et al.,2001).

Synapomorphic features of the orders that make up the panorpoid complex are "admittedly inconspicuous" according to Kristensen (1991). They include the vestigial or lost ovipositor, insertion of the pleural muscle on the first axillary plate, transversely divided larval stipes, and loss or addition of various muscles in the larval labium and maxilla. Within the panorpoid complex two well-substantiated sister groups (sometimes designated superorders) Antliophora (Mecoptera, Diptera, and Siphonaptera) and Amphiesmenoptera (Trichoptera and Lepidoptera) are recognized. An abundance of mecopteralike fossil wings have been recovered from Paleozoic strata, but it frequently has been difficult to determine whether these belong to Mecoptera, Diptera, or the stem group ancestral to both of these orders. Nevertheless, genuine Mecoptera (scorpionflies) are known from Upper Permian deposits and may have been the first endopterygotes to diversify widely. The close link between Diptera (true flies) and Mecoptera implied above, that is, by the inability to distinguish between fossil wings of the two groups, is supported by the existence of four-winged fossil "flies" (Permotanyderus and Choristotanyderus) in the Upper Permian. These may not be true Diptera but just off the main evolutionary line in a separate group Protodiptera. Interestingly, the only direct evidence for the existence of Paleozoic Diptera (a single wing of Permotipula patricia, collected from Upper Permian deposits in Australia during the 1920s) was lost for more than 50 years, only to be rediscovered in the British Museum (London) and redescribed in the late 1980s (Willmann, 1989). Though they may have originated from the mecopteroid stem group during the Carboniferous (Kukalova-Peck, 1991), the Siphonaptera (fleas) do not appear in the fossil record until the Lower Cretaceous. As their names indicate, some of these (Saurophthirus and Saurophthiroides) are thought to have possibly been parasites of flying reptiles. Because they are so highly modified for their ectoparasitic mode of life, comparative studies ofliving fleas must be interpreted cautiously. With their apodous larvae and adecticous pupae, fleas resemble Diptera, suggesting the two may be sister groups. However, most authors, noting similarities in sperm ultrastructure, thoracic skeleton, nervous system, foregut, and molecular genetic sequences believe that these indicate a sister-group relationship between the Mecoptera and Siphonaptera.

The monophyletic nature of the Amphiesmenoptera is unquestioned with more than 20 synapomorphies common to the Trichoptera (caddisflies) and Lepidoptera (butterflies and moths) (Kristensen, 1984). It is presumed that these orders had their origin in the Paleozoic from mecopteralike ancestors, though there is little in the fossil record to substantiate this claim. Microptysmella and related fossils from the Lower Permian may be members of the stem group from which the two orders are derived. From his comparison of primitive members of both orders, Ross (1967) suggested that the common ancestor was in the adult stage trichopteran and in the larval stage lepidopteran in character. In the evolution of Trichoptera the larva became specialized for an aquatic existence, but the adult remained primitive. Along the line leading to Lepidoptera the larva retained its primitive features, but the adult became specialized, especially in the development of the suctorial proboscis. The earliest genuine caddis fly fossils are from the Triassic and some of these are assignable to extant families. Most extant families probably originated in the Jurassic (Hennig, 1981), and caddis fly cases have been found in Lower Cretaceous deposits. Fossil Lepidoptera are known with certainty only from the Lower Jurassic onward, earlier specimens from the Triassic being more likely Trichoptera or Mecoptera. Like those of extant Micropterigidae, adults of the earliest Lepidoptera probably had chewing mouthparts and were pollen feeders;

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.

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