Pheromones

chapter 13 Pheromones are chemicals messages produced by one individual that induce a partic ular behavioral, physiological, or developmental response in other individuals of the same species. Like hormones, they are produced in small quantities; indeed, they are referred to in older literature as "ectohormones," a term that may take on renewed significance following the discovery that in termites juvenile hormone apparently serves also as a pheromone that regulates caste differentiation (Section 4.1.2). Pheromones may be volatile and therefore capable of being detected as an odor over considerable distances, or they may be non-volatile, requiring actual physical contact among individuals for their dissemination. They may be highly specific, even to the extent that only a particular isomer of a substance induces the typical effect in a given species. (As a corollary, closely related species often utilize different isomeric forms of a given chemical). Pheromones are released only under appropriate conditions, that is, in response to appropriate environmental stimuli, and examples of this are given below. Thus, whereas the neural and endocrine systems coordinate the behavior, physiology, and/or development of an individual, pheromones regulate these processes within populations.

Pheromones may be arranged in rather broad, sometimes overlapping, categories based on their functions. There are sex pheromones, caste-regulating pheromones, aggregation pheromones, alarm pheromones, trail-marking pheromones, and spacing pheromones.

4.1.1. Sex Pheromones

In the term "sex pheromones" are included chemicals that (1) excite and/or attract members of the opposite sex (sex attractants), (2) act as aphrodisiacs, (3) accelerate or retard sexual maturation (in either the opposite and/or same sex), or (4) enhance fecundity and/or reduce receptivity in the female following their transfer during copulation.

Sex attractants are typically volatile chemicals produced by either male or female members of a species, whose release and detection by the partner are essential prerequisites to successful courtship and mating. At the outset, it should be realized that the term "sex attrac-tant" is a misnomer; the chemical does not directly attract but initiates upwind orientation and movement by the recipient. Male-attracting substances are produced by virgin females of species representing many insect orders, but especially Lepidoptera and Coleoptera (for lists, see Tamaki, in Kerkut and Gilbert, 1985; Arn et al., 1992). Females release their pheromones only in response to a specific stimulus. Release may be influenced by age, reproductive status, time of day, presence of host plant, temperature, and wind speed. For example, many species of moths begin "calling" (everting their pheromone-secreting glands and exuding the chemical) 1.5-2.0 hours before dawn. Other Lepidoptera are stimulated to release pheromone by the scent of the larval food plant. Rhodnius prolixus females release pheromone only after a blood meal, and pheromone production in Periplaneta americana is arrested when the ootheca is formed. It seems that in species such as R. prolixus, cockroaches, locusts, and beetles, which have repeated cycles of oocyte development over a period of time, pheromone production is under the control of the endocrine system, especially the corpora allata, and that the effects of stimuli such as food intake or presence of an ootheca are mediated via the neuroendocrine system. In Musca domestica and perhaps other Diptera, pheromone synthesis is regulated by ovarian ecdysteroids, while in many moths PBAN (Section 3.1) mediates production of sex attractant (Tillman et al., 1999; Ryan 2002).

CH3-(CH2)2-CH = CH-CH = CH-(CH2)8-CHaOH A Bombykol ok

CH3-CK-[CH2}5-CH = CH-C00H £ 9 - Hydroxydscenoic acid

CH3-C-(CH2i5-CH =CH -COOH B 9-Oxodecenoic acid

D Undecone

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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