Glands of insects

Figure 3. Dependence of oxidase activity on insect development as indicated by conversion of (Z)-11-tetradecen-l-ol to (Z)-ll-tetradecenal in 30 min. by excised glands of H. subflexa. H. yirescens and H. zea. Bars indicate the activity in intact glands at each time relative to that in glands of insects of the same species 48 h after adult emergence (100%) (n - 10, each species).

Most animals possess effective mechanisms for the excretion of excess or waste products. In most of their tissues and body fluids therefore only small amounts of secondary products occur. High concentrations of secondary products may be present, however, in certain specialized cells and tissues, e.g., in the exocrine signal glands of insects (E 4), the defense glands of certain beetles and the skin glands of salamanders and toads (E 5.1), as well as in hairs and feathers, the scales of butterfly wings etc. 

Certain groups of secondary products protect animals against predation and microbial attack (Table 67). These substances may be either synthesized de novo in the animal body or are taken up with the food and are used directly or in a modified form. Some compounds are built, stored and secreted in special glands, e.g., the defense glands of insects and the skin glands of salamanders and toads. Others are constituents of blood or gut. Most of the toxins have a broad spectrum of activity against different kinds of predators or microorganisms. 

The principle of the master gland can be detected at rather early stages of phylogenesis several endocrine glands of insects are guided by the endocrine activity of certain nerve cells (neurosecretion cf. Sections 9 and 12). 

Pheromones Hormones produced by external glands of insects to attract insects of the same species. Commercially, they are used to attract insects for population quantification and control purposes. 

Terpenoid substances are of broad distribution and diverse function in insects. One set, elaborated by the mandibular glands of Acanthomyops claviger, acts both as a defensive secretion and as an alarm releaser. When fed Cu-labeled acetate or mevalonate, laboratory colonies of these ants produce radioactive citronellal and citral, providing unambiguous evidence for de novo synthesis of these terpenes by the ant. The incorporations of these precursors implicate the mevalonic acid pathway as the likely biosynthetic route. 

The extract, which is prepared with pheromoneglands severed exclusively from abdomens, can be directly analyzed by GC-MSwithout any purification. El at 70 eV is widely used for this analysis, and are liable spectrum is recorded with a sample at least at a level of several ng. The gland of a large insect such as a Noctuidae species contains around 10-100 ng of the sex pheromone [21], and,... 

The asopine bug Tynacantha marginata represents a case in point of the premature designation of insect-produced compounds as pheromones. Males of this species produce a novel tricyclic sesquiterpenoid 48 from their pheromone gland , which has been designated as a putative sex pheromone [64], apparently on the basis that it is produced only by males. No assessment of the biological activity of crude extracts from the bugs, the purified compound from the bugs, or the synthetic compounds (see below) has been reported in the primary literature. 

Three acyclic amines, dimethylamine (109), putrescine (111), and spermidine (110), have been isolated from the accessary sexual glands of the mature male desert locust, Schistocerca gregaria (Table VIII). In addition, A -pyrroline (12i) has been identified as a volatile emanating from the mature male locust colony (Table II). It is an oxidation product of putrescine and probably could be responsible for the maturation-accelerating effect observed to be specific to the mature male insect 106). 

Function and Chemistry of Plant Trichomes and Glands in Insect Resistance... 

Brossut, R., Dubois, P, Rigaud, J. and Sreng, L. (1975). Biochemical study of the secretion of the tergal glands of the Blattaria. Insect Biochemistry 5 719-732. 

Noirot, C. and Quennedey, A. (1974). Fine structure of insect epidermal glands. Annual Review of Entomology 19 61-80. 

Sreng, L. (1979a). Ultrastructure and chemistry of the tergal gland secretion of the male of Blattella germanica (L.) (Dictyoptera Blattelidae). International Journal of Insect Morphology and Embryology 8 213-227. 

Cockroach mating behaviors, sex pheromones, and abdominal glands (Dictyoptera Blaberidae). Journal of Insect Behavior 6 715-735. 

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