Pheromones obtained by various combinations

08/28/2015 18:42

Pheromones obtained by various combinations of evaporator spacings and release rates. Disruption above 90% appears to be obtainable with the expenditure of about 10 mg Iooplure per hectare per night. About 100 mg per hectare per night will apparently give close to 100% disruption. At an anticipated cost of Iooplure of less than $1.00 per gram, the 100 mg rate would cost less than $0.10 per hectare per night. The cost of producing and servicing substrates and of ‘wasting’ looplure, due to evaporation during the heat of the day when the moths are not active and to irreversible adsorption in the substrates, may be considerably higher. Learn about pheromones at 

Disruption was obtained at lower Iooplure release rates in a cool, low~'vind, coastal environment than in a hot, erratically windy, desert environment (Shorey et al. 1972). The degree of disruption attained appeared to be no better in low than in relatively high density moth populations (Shorey et al. 1972). This density—independent effect was not anticipated. We expected that disruption would be more effective in the low density populations in which the average male and female presumably must communicate over greater distances according to

These experiments with T. ni were not evaluated by direct measurements of reduction in fertile eggs, and thus larvae, of the next generation. It is likely that T. ni females fly long distances, possible many miles, between the time of mating and the time some days later when they complete oviposition. Therefore, the minimum-sized plot for accurate evaluation of the effect of communication disruption on the next generation will probably have to be several miles in radius. Such large plots have not yet been used by

Experiments were also conducted to determine whether the disruption of male orientation to virgin females caged in traps is truly indicative of an inability of the males to find pheromone-releasing females in the open field (Shorey et al. 1972). Virgin females were tethered in the field by lengths of thread glued to their thoraxes. The degree of prevention of mating among these tethered females when placed in Iooplure-impregnated plots agreed closely with the degree of communication disruption indicated by the standard trapping technique

It is unfortunate that we do not understand the exact mechanism by which male female communication is disrupted, as this knowledge would enable us to develop more intelligently based and effective behavioral control systems. Probably much of the disruption effect is due to adaptation of the olfactory sensory neurons and/or habituation in the central nervous system following exposure of the males to the continually present synthetic pheromone. Also, with much more pheromone probably being released into the air from the synthetic sources than from wild females, any tendency of males to orient toward pheromone sources would only serve to increase their state of adaptation and habituation. Males of the alfalfa looper, Autographa califomica (Speyer), and the soybean looper, Pseudoplusia includens (Walker), were also prevented from orienting to their females when in Iooplure-treated plots (Kaae et al. 1972).