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Sufficient Pheromone Attraction

Let's talk about pheromone attraction. The in which groups of virgin males and females were enclosed in 2-liter glass jars (Shorey et al. 1967) with sufficient attractant pheromones. Sufficient Iooplure was placed in some of the jars several hours before the time of mating to approach saturating the air. Under these conditions, no males mated with the females, even though the confined conditions restricted all moths to within 15 cm of one another and numerous females were observed in the supposed receptive position, with sex pheromone glands extruded and wings vibrating.


Apparently the males remained unresponsive because they could not detect the small additional increment of pheromone released by the females when in the presence of the relatively massive prevailing concentration of synthetic pheromone. In jars not saturated with Iooplure, many males oriented to and mated with receptive females. Learn more at


In principle, if males of T. 111' in the laboratory can be rendered incapable of responding to the natural female pheromone following their continued exposure to Iooplure, the same phenomenon should be capable of operation as a behavioural insect control in the field.

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Between 1966 and 1972, experiments were conducted to investigate the feasibility of disrupting T. ni pheromone communication in the field (Shorey et al. 1967, 1971, 1972; Gaston et al. 1967; Kaae et al. 1972, 1973a). In all experiments, looplure was released into the air from evaporators held at one m above the soil surface on wooden stakes. No attempt was made to use evaporation substrates that would be practical in commercial practice; instead, evaporators were designed in such a way that their rate of looplure release could be measured accurately. Most evaporators were based on the principle of a liquid film of pure Iooplure being exposed to the air. Evaporation rates were determined by direct weighing in the laboratory under conditions of controlled temperature and airflow. (Gaston et al. 1971). 

 Most experiments were designed to answer the question: if a given amount of Iooplure is to be maintained in the air above a certain land area, is it better that the pheromone evaporate from many sources, placed closely together, with each source releasing the chemical at a fairly low rate; or would better disruption result from a few widely separated sources, each releasing at a relatively high rate? Evaporation sources spaced 1, 3, 10, 30, 100, and 200 m apart were evaluated with evaporation rates from the sources ranging from 0.001 to 20 ,ug of looplure per min (table 22.2). The evaporators were placed in square, checkerboard arrays in the field, ranging from 6 x 6 (36 evaporators total) to 10 x 10 (100 evaporators total).


The experiments were evaluated by placing a trap baited with virgin T. rzi fe- males in the center of each array. The number of T. 111' males caught in the trap, relative to the number caught in an identical control trap in a nearby untreated area, was used as the indication of the amount by which communication had been disrupted. No optimum evaporation rate or separation between evaporators was found (table 22.2). The important characteristic appears to be the total amount of Iooplure released into the air per given surface area of land.