Let us talk about the top pheromones. Riddiford 1967; Riddiford and Williams l967a,b; Sharma et al l971;Aliniazee and Stafford 1972). However, most of these studies do not distinguish whether:

1) males and females aggregated at the larval host before pheromone communica- tion occurred; 2) females were able to emit pheromone only after they had been stimulated by the larval host; or 3) males were only able to respond to pheromone when simultaneously stimulated by the larval host. Riddiford (1967) and Riddiford and Williams (1967a,b) examined the host specificity of pheromone communication by the polyphemus moth, Antheraea polyphemus (Cramer), the larvae of which feed only on oak leaves. The chemical trans-2-hexenal, which is released from oak leaves, must be perceived by the female moth before she will release her phero- mone. Although leaves of many plant species contain trans-2-hexenal also, species other than oak release ‘masking’ odors which prevent the female moth from per- forming her pheromone releasing behavior. Check out more at  http://pheromones-work.weebly.com

Some insect species are more general in their feeding habits. Cabbage looper larvae are fairly polyphagous and traps baited with virgin female moths of this species captured large numbers of males irrespective of the presence or absence of larval hosts in the vicinity (Saario et al. 1970).

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Pheromone variables

A number of physiological factors may operate simultaneously in insects to control the occurrence and the intensity of expression of pheromone production, phero- mone release and pheromone responsiveness.

Top Pheromone behavior

The top pheromone extracts when the laboratory temperature was maintained at 20-23 °C than when it was maintained at 27 °C (Klun 1968). These pheromone studies with the European corn borer support the observations of Sparks (1963) that cool temperatures typical of night are more conducive to mating than warmer temperatures.

Although little research has been conducted on the control of pheromone re- lease by temperature, it appears likely that for any given species, optimal release would occur in the same range of temperature that is conducive to pheromone responsiveness by the opposite sex. Thus, the minimum temperature for pheromone release by females of the cabbage looper moth (Sower et al. 1971) and for pheromone responsiveness by males of this species (Shorey 1966) is near 12 °C. Check out the top pheromones at http://www.pheromones-experts.com.

Air velocity is an important controlling factor for those insect species using sex pheromones for communication over distances greater than a few cm. Velocities lower than some minimum value may prevent the responding sex from approaching the pheromone source because: 1) the pheromone may not be carried far from its source; and/or 2) the resulting, slowly formed, aerial trail may be so disrupted or otherwise improperly constructed that the responding insects cannot orient along it to the source. High air velocities may inhibit successful response because: 1) the wind speed may exceed the flight speed of the responding insects; and/or 2) the aerial trail may be improperly constructed for normal orientation behavior.

Examples of air velocities that do or do not allow approaches by the responding sex are discussed in ch. 5.

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