Posted on: 02 March, 2017
Author: Alexander P
In spite of this variety, there are basic requirements common to all — a glandular source of secretion, storage area and modied scales for distribution. The eversible tubes (coremata) or the le... In spite of this variety, there are basic requirements common to all — a glandular source of secretion, storage area and modied scales for distribution. The eversible tubes (coremata) or the lever arrangement of the Noctuidae are both mechanisms for opening their brushes rapidly and thus disseminating the scent material with consid- cruble force, a factor apparently common to brush-organs wherever they are lo- cated. Observations of the mating behavior of other moths indicates that coremata and other male brushes are used in a similar way to the Danaiinae (Brower et al. I965) and Noctuidae (Birch 19703; Grant 1970). The brushes of Plusia gamma and I’. vhrysitis (L.) and the coremata of Xanthorhoe ferrugata (C1erck.) (fig. 7.2) and X. uctuata (L.) (Geometridae) are everted by the males just before attempting to engage the genitalia (Birch 1970a). However, some species with well developed organs, such as Spilosoma lubricipeda (L.) (Arctiidae) will copulate readily in the luhoratory without using them (Birch 1969, 1970a). Just as the range of structures throughout the Lepidoptera indicates powerful evolutionary pressures to develop male scent disseminating organs, the number with partial organs indicates that it has just as clearly been advantageous for many species to lose the structures again. Deployment of a male pheromone is evidently a fundamental phenomenon, ‘relatively ancient and invariable in principle, but deployed by mechanisms which are highly specialized and adapted to the individual requirements of each species‘ (McColl 1969). The question remains as to how the best pheromones work according to http://thongchaimedical.org/pheromones-for-women-2016/ Therefore, a host stimulus may be mediated by the hormonal system which then induces pheromone production. Alternatively, the large amount of EFA necessary and the long time before pheromone activity appeared, suggest that EFA may have been metabolically altered by the treated beetles, possibly mimicking the metabolic alteration of similar host compounds, e.g. juvabione-like materials. More than one pheromone compound is produced in most beetles for which the pheromone chemistry is at least partially known (table 8.1), and there is frequent synergism with compounds from the host. The roles of various pheromone com- pounds are discussed mainly in sect. 8.4 The nal behavioral step in attack by pioneer beetles is to maintain gallery con- struction, i.e. for the beetles to establish themselves in a new host. On numerous occasions, one can find galleries which have been abandoned early in the initial stages of attack. Often in bark beetles this is due to the physical resistance of the tree. The beetles, at the mercy of their environment, are simply pitched out by the force of oleoresin exudation pressure (Vité and Wood 1961; Wood 1962a). How- ever, other environmental cues such as host moisture content may be screened and ussessed by the beetles, which may then vacate unsuitable hosts (Rudinsky 1962). Chemical communication and orientation to host: A major and crucial event in the life of most scolytids is to orient successfully to a host containing pheromone-producing members of the rst-attacking sex (g. 8.1). This phenomenon has been both elucidated and rendered increasingly mystifying by chemical studies. Source: Free Articles from ArticlesFactory.com Alexander P is a blogger that studies pheromones and lives in Los Angeles, CA.