Box 52 Nuptial feeding and other gifts

Feeding of the female by the male before, during, or after copulation has evolved independently in several different insect groups. From the female's perspective, feeding takes one of three forms 1 receipt of nourishment from food collected, captured, or regurgitated by the male (Box 6.1) or 2 obtaining nourishment from a glandular product (including the spermatophore) of the male or 3 by cannibalization of males during or after copulation. From the male's perspective, nuptial feeding may...

The Tracheal System And Gas Exchange

In common with all aerobic animals, insects must obtain oxygen from their environment and eliminate carbon dioxide respired by their cells. This is gas exchange, distinguished from respiration, which strictly refers to oxygen-consuming, cellular metabolic processes. In almost all insects, gas exchange occurs by means of internal air-filled tracheae. These tubes branch and ramify through the body (Fig. 3.10). The finest branches contact all internal organs and tissues, and are especially...

Box 33 The filter chamber of Hemiptera

Alimentary Canal Insect

Most Hemiptera have an unusual arrangement of the midgut which is related to their habit of feeding on plant fluids. An anterior and a posterior part of the gut (typically involving the midgut) are in intimate contact to allow concentration of the liquid food. This filter chamber allows excess water and relatively small molecules, such as simple sugars, to be passed quickly and directly from the anterior gut to the hindgut, thereby short-circuiting the main absorptive portion of the mid-gut....

Diversity In Genitalic Morphology

The components of the terminalia of insects are very diverse in structure and frequently exhibit species-specific morphology (Fig. 5.5), even in otherwise similar species. Variations in external features of the male genitalia often allow differentiation of species, whereas external structures in the female usually are simpler and less varied. Conversely, the internal genitalia of female insects often show greater diagnostic variability than the internal structures of the males. However, recent...

Box 41 Aural location of host by a parasitoid fly

Visual Organ Insects

Parasitoid insects track down hosts, upon which their immature development depends, using predominantly chemical and visual cues (section 13.1). Locating a host from afar by orientation towards a sound that is specific for that host is rather unusual behavior. Although close-up low-frequency air movements produced by prospective hosts can be detected, for example by fleas and some blood-feeding flies (section 4.1.3), host location by distant sound is developed best in flies of the tribe Ormiini...

Box 43 Reception of communication molecules

Aphrodisiacs Danaus

- trichogen cell -tormogen cell Pheromones, and indeed all signaling chemicals (semio-chemicals), must be detectable in the smallest quantities. For example, the moth approaching a pheromone source portrayed in Fig. 4.7, must detect an initially weak signal, and then respond appropriately by orientating towards it, distinguishing abrupt changes in concentration ranging from zero to short-lived concentrated puffs. This involves a physiological ability to monitor continuously and respond to...

Lifehistory Patterns And Phases

Immature Stages Larva

Growth is an important part of an individual's ontogeny, the developmental history of that organism from egg to adult. Equally significant are the changes, both subtle and dramatic, that take place in body form as insects molt and grow larger. Changes in form (morphology) during ontogeny affect both external structures and internal organs, but only the external changes are apparent at each molt. We recognize three broad patterns of developmental morphological change during ontogeny, based on...

The Extant Hexapoda

The Hexapoda (usually given the rank of superclass) contains all six-legged arthropods. Traditionally, the closest relatives of hexapods have been considered to be the myriapods (centipedes, millipedes, and their allies). However, as shown in Box 7.1, molecular sequence and developmental data plus some morphology (especially of the compound eye and nervous system) suggest a more recent shared ancestry for hexapods and crustaceans than for hexapods and myriapods. Diagnostic features of the...

The Thorax

Pterothoracic Notum Insects

The thorax is composed of three segments the first or prothorax, the second or mesothorax, and the third or metathorax. Primitively, and in apterygotes bristletails and silverfish and immature insects, these segments are similar in size and structural complexity. In most winged insects the mesothorax and metathorax are enlarged relative to the prothorax and form a pterothorax, bearing the wings and associated musculature. Wings occur only on the second and third segments in extant insects...

Maxilla

Apis Mellifera Head

Head and sometimes subdivided into a submentum and mentum and the free distal prementum, typically bearing a pair of labial palps lateral to two pairs of lobes, the mesal glossae singular glossa and the more lateral paraglossae singular paraglossa . The glossae and paraglossae, including sometimes the distal part of the prementum to which they attach, are known collectively as the ligula the lobes may be variously fused or reduced as in Forficula Fig. 2.10 , in which the glossae are absent. The...