This type of pheromone behavior

Fig19

This type of pheromone behavior has been extensively analyzed by Kennedy and associates, who showed that visual cues with the ground were necessary to orient the moth; they termed this behavior odor-regulated, optomotor anemotaxis, and reversing anemomenotaxis (upwind zigzag flight).

Cardé and associates, building on the above concepts and terminology, have constructed a model for the mating behavior of male gypsy moths by using both wind tunnel and field observations. In the wind tunnel, the male is aroused from quiescence by the introduction of a pheromone plume, and responds by general body movements, wing fanning, walking, and finally flight. Regulating its net groundspeed by visual cues from the ground, it flies upwind (positive anemotaxis) remaining in the plume by zigzag flight (reversing anemomenotaxis). Responding to pheromone concentration and visual cues on nearing the female, the male decreases flight speed, lands, walks while wing fanning, locates the female, and proceeds to mate. Learn more about pheromones at http://sundowndivers.org/?p=82 and http://mpommett.blog.fc2.com/blog-entry-3.html/.

Such pheromone behavior occurs primarily with “sparse” populations (defined by Doane” as less than ten females per hectare but with a precise definition uncertain). Male mating behavior in dense populations may be very different,” with long-range orientation being unnecessary or perhaps impossible because of confusion resulting from multiple pheromone sources. Accordingly, at least some males adopt a surface-searching strategy for mate finding.

Hidaka” suggested that pheromones are ineffective in guiding males to a female from a distance and concluded that in Japan, the male gypsy moth searches for its mate visually in the manner of a butterfly. In Hidaka’s model of mate-searching behavior, the male flies about at random, possibly stimulated by a very low concentration of pheromone in the air.

When by chance the male enters the very limited “effective sphere” of the pheromone, its flight pattern changes, as does it search behavior. According to Hidaka, the pheromone only cues the moth that “a female is very close to you”; then the male seeks the next cue, which is probably visual. Hidaka believes that this model accounts for two common observations: (1) male searching is very ineffective: “a female gypsy moth situated on the bark of a cherry tree could be located and mated not before ten or more males had approached, eagerly searched and eventually flew away in vain”; (2) male gypsy moths are commonly observed to “float” in front of a synthetic pheromone source, suggesting that the moth switches cues in response to an elevated pheromone concentration, specifically that met about 10 cm from the female, the reach of visual location. It should be noted that the gypsy moth in Japan may have behavioral traits that differ from those of Europe and North America.

Charles-Dominique (1971a) doubts that under natural conditions lorises make much use of their pheromone in orientation. Perodicticus potto, for instance, travels through its whole natural territory without using fixed pathways. Moreover, urine is not deposited throughout the territory but only in particular places. Although urine marks left in some places within the territory might function as reminders during orientation, Charles-Domi- nique ( 197 l a) suggests that their more important function is in territorial and social behavior, a possibility which is also discussed by Seitz (I969).

1 9.4.2. Pheromone Territorial functions

In many primates, especially in prosimians and in New World monkeys, scent marking is thought to play a role in territorial behavior. However, only a few examples of ‘territorial marking’ can be reviewed here. Seitz (1969) introduced Nycticebus coucang into a uniformly equipped test territory, bordered at two sides by Nycticebus living cages, at one side by a Loris tardigradus cage and at the fourth side by no other animals.

The males marked most frequently in the area adjacent to the living cages of the same species, less frequently in the area adjacent to the Loris cage and little in the center of the territory and in the area not bordered by a neighbor.

Females, however, limited their marking activity to the center of the test territory. Similar observations are reported for Galago senegalensis in the field by Sauer and Sauer (1963). Charles-Dominique (197lb) reports that wild galagos and pottos deposit urine marks particularly in zones in which the territories of the individuals overlap.

Wild Lepilemur mustelinus J. Geoffroy males deposit urine and feces on exposed branches of their territories which seem to serve as lookout points for observing neighbors in adjacent territories (Charles-Dominique and Hla- dik 1971). The highly ritualized territorial dispheromonestes among Propithecus verrauxi Grandidier groups in their natural environment involve a frenzy of scent marking (Jolly 1966). Marking is also a regular component of the complex and ritualized territorial ceremonies of wild Titi monkeys (Callicebus moloch Hoffmannseg) (Mason 1966) and is regularly seen when groups of captive marmosets engage in aggressive encounters (Epple personal observation).

Richerson and associates also emphasized the role of vision in the searching behavior of male gypsy moths. In dense populations, they found that males did not orient directly to calling females, either by zigzag or straight-line flight. Instead, the males oriented to vertical silhouettes such as trees. Richerson et al.“ presented an analysis of mate-searching behavior based on the concept of “active space” developed by Bossert and Wilson.” Learn more about pheromones at http://youthbruce.com/2016/05/03/does-max-attraction-gold-work/

They suggested that males in an area where the pheromone concentration is below a behavioral threshold will fly randomly without searching. When entering an “active space” where the pheromone concentration is above threshold level, the male will orient to some or all the trees within that active space.

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