The structure and development of flightless coleoptera: A light and electron microscopic study of the wings, thoracic exoskeleton and rudimentary flight musculature

Abstract

It is a striking fact that the majority of insect orders include members that exhibit reduction or loss of wings in the adult.The flight musculature of the typical winged insect is housed in the meso-and metathoracic segments; sometimes (e.g. Diptera) the former, and at other times the latter (e.g. Coleoptera) assumes prime importance in this respect, while among the less specialized orders such as the Odonata and Orthoptera the labor involved in flight is evenly divided between the two. The wing-bearing segments of an insect have been modified more or less extensively to accommodate the flight muscles and to meet the mechanical requirements imposed by flight. In an insect that displays wing reduction or loss it is to be expected that a parallel modification of the flight muscles and their attachments should OCcur, and the work described here is in part concerned with this phenomenon in the Coleopter a.Loss of flight and wing reduction is very widespread among the beetles. Nevertheless, while an extensive literature is available on the anatomy of the reduced wings, information on the concomitant modifications undergone by other parts of the body of such insects, and notably by the flight musculature, is very scarce and incomplete, and the present work serves as a contribution to the developmental aspects of this modification.It will be demonstrated that wing reduction cannot normally be the initial factor causing inability to fly. It is well known to all who have collected beetles in the field that many species, though winged, are never seen in flight; among the Carabidae, J. MORPH., 114: 107-184.for example, few species are seen on the wing when many phytophagous species are flying actively. Lindroth ('49) in his extensive work on the Fennoscandian carabids investigated the wing condition and flight performance of each. Of 362 species examined, he found that 177 had been seen in flight though in the case of 47 of these, only outside this geographical area. A further 86 fully winged species were never observed to fly; 50 were flightless and showed wing dimorphism (some individuals being macropterous and others of the same species having reduced wings), and 49 species were exclusively shortwinged or brachypterous. Despite this well documented evidence of variation in flight ability, little detailed information is available on the condition of the flight muscles of fully winged or brachypterous flightless species.Dimorphic species greatly exceed in number those exhibiting all grades of wing reduction, and this fact, together with the observed constancy in the structure of the wing vestiges in different individuals of brachypterous species, points to a genetic stability underlying the modifications accompanying loss of flight. Jackson ('28) concluded that brachyptery in Sitona hispidula behaves as a simple dominant with respect to macroptery, and Lindroth ('46) found a similar mechanism operating in Pterostichus anthracinus. The extent to which the wings and exoskeletal features of the metathorax deviate from the ...

Physiology and Ecology of Dispersal Polymorphism in Insects

“…These muscles are reduced in size by 40% or more in the brachypter (77, 78, 111; AJ Zera & K Grudzinski, unpublished data). Reduced fl ight-muscle mass results primarily from inhibition of muscle growth (77,78,104,111).…”

Morphological and functional maturation of a skeletal muscle regulated by juvenile hormone

“…Fig.·7, together with a set of control experiments using bathapplied proctolin Proctolin (10 -9 mol l -1 ) Saline Proctolin (10 -9 mol l -1 ) The growth described in the present study was not only restricted to the muscles but also the apodeme, which functions as an insertion element of muscle fibres. Smith (1964) speculated that muscles and their integumental attachment codevelop during ontogenesis. In the adult flesh-fly, Sarcophyga falculata, Schlein (1972) reported post-emergence enlargement of an apodeme by the deposition of endocuticle and growth of associated muscle fibres influenced by endocrine factors.…”

Genetic basis and fitness consequences of winglessness in the two-spot ladybird beetle, Adalia bipunctata

“…Life history traits accrued by the flightless form are often interrelated or reinforcing, including higher fecundity, earlier age at first reproduction and a longer lifespan (Ritchie et al, 1987;Denno et al, 1989). Numerous body shape changes are also associated with the reduction of the proportion of the thorax in flightless forms (Smith, 1964). These pleiotropic effects can be mediated physiologically by endocrine products, such as the titer of juvenile hormone acting as the common link between reproduction and wing formation (Roff, 1986a;Roff and Fairbairn, 1991).…”